# Atapa for Mac: full text > Atapa is a Mac menu bar app that warms and dims the screen from daylight (6500K) to deep red (500K) through the evening. It works on M5 Pro and M5 Max MacBook Pros, where apps that tint through a gamma table do nothing. It costs $12 once for all of your own Macs, with a 14-day trial and a 14-day refund. It has no account and no network code. It requires macOS 14 or later on Apple silicon. Kevin Hofmann makes it at SOULRISE LLC. ## Home URL: https://atapa.app/ Atapa for Mac warms and dims the screen from daylight at 6500K to deep red at 500K as the evening goes on. It works on M5 Pro and M5 Max MacBook Pros, where a gamma table is accepted by macOS and never shown (Apple bug FB22273730, still open on macOS 27.2 as of 26 October 2026). $12 once, 14-day trial, no account, no network code. ## Pricing URL: https://atapa.app/buy/ Atapa for Mac is $12 once (USD). The first 14 days of sale are $9. One licence covers all of your own Macs. Updates for version 1 are included. The trial is 14 days and does not ask for a card. The refund window is 14 days. VAT is added at checkout by Lemon Squeezy, the seller of record, for SOULRISE LLC. The app checks the key on the Mac and does not contact a server. After the trial: Atapa never stops working. Days 1–14 are the trial. Days 15–28 are the full app with a banner asking for a key. From day 29 without a key, warmth stops at 2700K; dimming, the evening curve and everything else keep working. A key lifts the limit at once. ## Download URL: https://atapa.app/download/ Atapa 1.0 for Mac, 3.3 MB, requires macOS 14 or later on Apple silicon. Intel Macs are not supported in 1.0. The download is a notarized disk image. The tint does not need Screen Recording. Accessibility is asked only if you want the brightness keys to drive the dimming. ## Changelog URL: https://atapa.app/changelog/ Atapa 1.0 (2026-11-03): - Warms and dims the screen from 6500K to 500K through the evening. - Readable red: blue and green are folded into red, so text and links stay visible at 500K. - Setup is one question: when do you usually go to bed? Sunset comes from your time zone. - Three intensities: Gentle (1900K), Warm (1200K) and Deep red (500K). - Works on M5 Pro and M5 Max MacBook Pros through the display pipeline, where gamma-table apps do nothing. - Dims below the lowest brightness step; the brightness keys can drive it. - Shortcuts actions, a Focus filter, a URL scheme and a command line. - Eye rest, opt-in: every 20 minutes the screen eases down for 20 seconds. - Tonight's ring: an estimate of the body-clock light your screen gave off this evening. - A guard process resets the screen if Atapa ever quits unexpectedly. ⌃⌥⌘⌫ always restores true color. - No account, no analytics, no network code. - Licence: 14-day trial, then the full app with a banner for 14 more days; from day 29 warmth stops at 2700K until a key is entered. It never stops working. ## f.lux on an M5 Pro: what still works URL: https://atapa.app/alternatives/flux/ Updated: 2026-10-29 If f.lux does nothing on your M5 Pro or M5 Max, Night Shift still changes the screen with nothing to install; its warmest step is mild orange. For deep red on that chip, Atapa tints in the display pipeline to 500K. On our M5 Pro on 29 October 2026, f.lux 42.2 said it was on; the panel did not change. This is not a ranked list of f.lux alternatives. It is what still works on an M5 Pro or M5 Max MacBook Pro, in the order of least effort first, with the date we checked each one. We make Atapa, which is one of the options, so read that section as the vendor's. ## Why f.lux stopped changing the screen Since the M5 Pro and M5 Max, macOS accepts the gamma table that f.lux sets and never shows it. Apple reproduced the bug, and it was still open on macOS 27.2 as of 26 October 2026. f.lux, Lunar and MonitorControl are named in Apple's thread; the report numbers and the thread are on [the M5 page](/m5/). The f.lux developer is tracking the bug and waiting on Apple. On our 14-inch M5 Pro, macOS 27.2, on 29 October 2026, f.lux 42.2 with the Daytime slider at its lowest stop, 2700K (Tungsten), said "The sun is up" and the panel did not change. The one-minute check you can run yourself is on [the M5 page](/m5/). ![f.lux 42.2 preferences on our M5 Pro on 2026-10-29: the Daytime slider at its leftmost stop, 2700K (Tungsten). The panel behind this window did not change.](/evidence/flux-m5pro-2026-10-29.webp) ## Night Shift: nothing to install Start here. Night Shift uses a different path from the gamma table and still changes the screen on M5 Macs. Open System Settings, Displays, Night Shift. Turn on "Turn on until tomorrow", or set a Sunset to Sunrise schedule, and move Color temperature to More Warm. On our M5 Pro on 29 October 2026, More Warm was a mild orange, never red. Apple does not publish a kelvin figure; independent measurements put the warmest setting around 2700 to 3000K. Night Shift does not dim the screen below the hardware minimum, and it has no red setting. For many people it is enough, and it costs nothing. ![macOS Night Shift settings on our M5 Pro on 2026-10-29: "Turn on until tomorrow" on and the Color temperature slider at More Warm.](/evidence/nightshift-m5pro-2026-10-29.webp) ## Atapa: deep red on that chip If Night Shift's warmest step is still too blue in a dark room, this is the option we know changes an M5 Pro screen all the way down. We make it. Atapa tints in the display pipeline instead of through the gamma table. On the same M5 Pro on 29 October 2026 it went from 6500K to 500K, and from 1500K down it folds blue and green into red so links and icons stay visible. It dims below the lowest brightness step, and it ships Shortcuts actions, a Focus filter, a URL scheme and a CLI. Intel Macs are not supported in 1.0. The trial does not ask for a card. ![Atapa's popover holding 500K at 70% brightness on an M5 Pro, with the footer line "Color matrix · Apple M5 Pro".](/renders/popover-500K-light.webp) ## Sundown: not on this Mac yet, by its own account Sundown is the most complete warmth app on features, with a large guide library, a Windows build in progress, and a lot of customization. On an M1 through M4 Mac it is a reasonable choice. On our M5 Pro, macOS 27.2, on 29 October 2026, Sundown 1.6.4 showed its own notice: "Warming isn't available on this Mac yet. Your Mac's display ignores the usual way apps warm the screen, so for now Sundown leaves your screen's color, brightness, Night Shift and True Tone as they are. We're working on it." We recheck after each Sundown update. Its site is [trysundown.com](https://trysundown.com). ## Solace and CircadianShield: untested on M5 by their own sites [Solace](https://theodorehq.com/solace) bundles dark mode switching, wallpapers and warmth for $4.99 once (read 2026-10-28) and does not state M5 support. [CircadianShield](https://circadianshield.com) is $47 once for Mac and Windows, warmest 1800K, and its site said on 2026-10-28 that M5 has not been tested yet. We have not installed either on our M5 Pro, so this page does not say whether they work there. On an M1 through M4 Mac both are worth a look. ## BetterDisplay: for display configuration, not an evening schedule BetterDisplay is named in Apple's thread because its color-table adjustments stopped applying. Its maintainer wrote on 13 October 2026 that image adjustments now go through a compositor filter instead. If what you need is brightness and display configuration, it is the right tool. It is not a sunset-to-bedtime warmth app. ## What each option does on an M5 Pro | Option | On the M5 Pro built-in display | Install | Checked | |---|---|---|---| | Night Shift | Changes the screen; mild orange at More Warm, never red | None | 2026-10-29 | | Atapa 1.0 | Changes the screen, 6500K to 500K, readable red | Download, 14-day trial | 2026-10-29 | | f.lux 42.2 | Says it is on; the panel does not change | Free | 2026-10-29 | | Sundown 1.6.4 | Its own notice: warming is not available on this Mac yet | Trial asks for a card | 2026-10-29 | | CircadianShield | "M5 has not been tested yet", its site | $47, no trial | 2026-10-28 | | Solace | Not stated; not tested by us | $4.99 | 2026-10-28 | | BetterDisplay | Compositor-filter image adjustments since 2026-10-13; display configuration | Free tier | 2026-10-28 | ## If you want to wait for Apple That is a fair choice. Apple reproduced the bug and BetterDisplay's maintainer said on 13 October 2026 it was still with engineering. When the fix ships, f.lux will work on these Macs again. Until then, Night Shift covers a mild tint for free, and Atapa covers deep red without depending on the fix. We retest after each macOS update and date the result on [the M5 page](/m5/). ### Questions **Why does f.lux do nothing on an M5 Pro?** Since the M5 Pro and M5 Max, macOS accepts the gamma table that f.lux sets and never applies it (an Apple bug, reproduced by Apple and still open on macOS 27.2 as of 26 October 2026). The app cannot see the failure because reading the table back returns what it set. The f.lux developer is tracking the bug in the f.lux forum and waiting on Apple. On Intel and M1 to M4 Macs, f.lux works as before. **What is the quickest replacement with nothing to install?** Night Shift. Open System Settings, Displays, Night Shift, turn on "Turn on until tomorrow" or set a schedule, and move Color temperature to More Warm. On our M5 Pro on 2026-10-29 it turned the panel mildly orange. Apple publishes no kelvin figure; independent measurements put More Warm around 2700 to 3000K. It never goes red and it does not dim. **Which app goes to deep red on an M5 Pro today?** Atapa, as far as our own testing goes. On a 14-inch M5 Pro with macOS 27.2 on 2026-10-29 it changed the screen from 6500K to 500K, with blue and green folded into red so links stay readable. We make Atapa. Sundown 1.6.4 on the same Mac showed its own notice that warming is not available on this Mac yet. CircadianShield's site says M5 has not been tested. **Should I wait for Apple to fix it?** You can. Apple reproduced the bug, and BetterDisplay's maintainer wrote on 13 October 2026 that it was still with engineering. When it is fixed, f.lux will work on these Macs again. Until then Night Shift covers a mild tint, and Atapa covers deep red without depending on the fix. We retest after each macOS update and date the line on the M5 page. **Do Sundown, Solace or CircadianShield work on M5 Pro?** Sundown 1.6.4 told us itself on 2026-10-29: "Warming isn't available on this Mac yet." CircadianShield's site said on 2026-10-28 that M5 has not been tested yet. Solace does not state it and we have not installed it on our M5 Pro. All three are worth a look on an M1 to M4 Mac, where the gamma table still applies. ### Sources - f.lux (justgetflux.com), Mac version 42.2: https://justgetflux.com (read 2026-10-29) - f.lux forum: macOS Tahoe 26 notes: https://forum.justgetflux.com/topic/8640 (read 2026-10-29) - f.lux forum: the M5 Pro thread: https://forum.justgetflux.com/topic/8639 (read 2026-10-29) - Apple Developer Forums: the M5 Pro gamma-table thread: https://developer.apple.com/forums/thread/819331 (read 2026-10-29) - Apple Support: Use Night Shift on your Mac: https://support.apple.com/en-us/ht207513 (read 2026-10-28) - BetterDisplay: the maintainer's note of 2026-10-13: https://github.com/waydabber/BetterDisplay/discussions/5217 (read 2026-10-28) - Sundown (trysundown.com), version 1.6.4: https://trysundown.com (read 2026-10-29) - Solace by Theodore HQ: https://theodorehq.com/solace (read 2026-10-28) - CircadianShield (circadianshield.com): https://circadianshield.com (read 2026-10-28) ## Screen-warmth apps for Mac: f.lux, Night Shift, Sundown, CircadianShield, Solace, Iris and Atapa, in one table URL: https://atapa.app/compare/ Updated: 2026-10-29 Screen-warmth apps for Mac differ on four things that change the purchase: whether the tint appears on an M5 Pro built-in display, how far toward red they go, whether blue links stay visible at that setting, and whether the app phones home. This table was checked on 2026-10-29. We make Atapa. Where another app is the better pick, the row says so. ## How we checked We installed each app on a 14-inch MacBook Pro M5 Pro, macOS 27.2, on 2026-10-29, and looked at the built-in panel with our eyes, because captures cannot show the tint. The apps were f.lux 42.2 (the latest Mac build), Sundown 1.6.4 (the trial) and Night Shift at More Warm. Atapa was the 1.0 build of the same day. Everything else in the table comes from each vendor's own site, read on 2026-10-28 or 2026-10-29, with the URL in the cell. Where a vendor publishes no figure, the cell says so instead of guessing. Prices are the ones on the vendor's page or in its checkout on that date; Sundown's own posts list different prices, so we used its 1.6.4 checkout. ## Who each app suits | App | Pick it when | Skip it when | |---|---|---| | Night Shift | You want zero install and a mild warm tint is enough | You want red, or you read in a dark room | | f.lux | You want a free app, you are on Windows, or on an Intel or M1 to M4 Mac | You are on an M5 Pro or M5 Max: on our panel it changed nothing on 2026-10-29 | | Sundown | You want its guide library, its customization, or a Windows build later, on an M1 to M4 Mac | You are on an M5 Pro or M5 Max: its own app said warming is not available yet on 2026-10-29 | | CircadianShield | You want a Windows and Mac licence and a melanopic dashboard | You are on an M5 (its site says not tested) or you want a free trial | | Solace | You mostly want dark mode and wallpaper switching, with warmth as one feature | You want deep red or a published kelvin figure | | Iris | You want many presets and a Windows build | You want a dated Mac release or offline licensing | | Atapa | You are on an M5 Pro or M5 Max, or you want readable deep red at 500K, paid once, with no network code | You are on an Intel Mac (not supported in 1.0) or you want Windows | ## Choose f.lux if You want a free app and you are on Windows, or on a Mac where gamma tables still apply: Intel, and M1 through M4. f.lux has a sunset schedule and color effects down to Ember (about 1200K, per competitor posts). Its Mac build has had a long quiet period (Sundown gives 17 May 2023 as the last release; we saw version 42.2 on 2026-10-29), and it is named in Apple's thread 819331 as one of the apps the M5 gamma bug breaks. On our M5 Pro on 2026-10-29 it said it was on and the panel did not change. Details on [the M5 page](/m5/). ## Choose Night Shift if A mild warm tint is enough for you. It is built in, it needs no install, and it still changes the screen on M5 Macs: on our M5 Pro at More Warm on 2026-10-29 it was mildly orange. It never goes red. Apple publishes no kelvin value; independent measurements put the warmest setting around 2700 to 3000K. It has a schedule and a Control Center toggle, and nothing to pay. ## Choose Sundown if You want a large library of guides, a Windows build (in progress, per its site), and a lot of customization: key pop-up styles, a Sound Studio, panel backgrounds, ambient-light dimming and room adaptation. Those are real advantages. Its site says zero telemetry. The published prices are $79 lifetime, $39 a year or $4.99 a month, and the 7-day trial asked for a card at checkout on 2026-10-29. On an M5 Pro or M5 Max, read its own notice first. On our 14-inch M5 Pro, macOS 27.2, on 2026-10-29, Sundown 1.6.4 said: "Warming isn't available on this Mac yet." They say they are working on it, and we recheck after each update. Its blog describes its flicker-free mode as dimming through the gamma table, which is the path macOS ignores on those chips. ## Choose CircadianShield if You want one licence for Mac and Windows, and a dashboard that reports melanopic light. It is $47 once for up to 2 computers, with a 30-day refund and no free trial. Its warmest published setting is 1800K. Its own site lists Apple silicon M1 through M4 Max and says M5 has not been tested yet (read 2026-10-28). It sends anonymous usage statistics, off by default. ## Choose Solace if You mostly want dark mode switching and wallpapers, with screen warmth in the same app, for $4.99 once (read 2026-10-28). It requires macOS 13 or later. It publishes no kelvin figure and does not state M5 support, so on an M5 Pro you would be testing it yourself. ## Choose Iris if You want preset depth and a Windows build. It is an older Mac app; Sundown's posts say no Mac update since 2022, and its pricing page had moved when we checked on 2026-10-28 (about $2 a month or $10 to $15 licences, to be re-checked). Licence activation is online. It does not state M5 support. ## Choose Atapa if You are on an M5 Pro or M5 Max and you want the screen to actually change, or you want deep red that stays readable on any Apple silicon Mac. At 500K, Atapa folds blue and green into red so links and syntax colors remain visible; a plain red filter turns them black. It dims below the lowest brightness step, has Shortcuts actions, a Focus filter, a URL scheme and a CLI, and contains no network code. $12 once for all of your own Macs, 14-day trial without a card, 14-day refund. Intel Macs are not supported in 1.0. ![Atapa's popover at 500K on an M5 Pro: deep red held with the warmth slider at the bottom of its range and brightness at 70%, with Gentle, Warm and Deep red as the three intensity stops.](/renders/popover-500K-light.webp) ## What the table does not say Gloam and Abendrot are free, open-source Mac warmth apps with little published testing on M5, so they are not in the table. Lunar, BetterDisplay and MonitorControl are brightness and display-configuration tools, not evening-warmth apps; they are named in Apple's thread because color-table adjustments no longer apply, and BetterDisplay's maintainer moved image adjustments to a compositor filter on 2026-10-13. The table is not a sleep claim. None of these apps, Atapa included, has been shown to improve sleep. What a screen can and cannot do is on [the science page](/science/). ### Questions **Which Mac warmth apps change the screen on an M5 Pro?** On our 14-inch M5 Pro with macOS 27.2 on 2026-10-29: Night Shift changed the screen (mildly orange at More Warm) and Atapa changed it (down to 500K). f.lux 42.2 said it was on and the panel did not change. Sundown 1.6.4 showed its own notice that warming is not available on this Mac yet. CircadianShield's site says M5 has not been tested. Solace and Iris do not state it. **Which is the warmest setting each app offers?** Atapa and Sundown both go to 500K; Sundown's figure is its own claim, and on our M5 Pro its warming was not available. CircadianShield publishes 1800K. f.lux's quick-start page lists 1900K for daytime, and its Ember effect is about 1200K per competitor posts. Apple publishes no number for Night Shift; independent measurements put More Warm around 2700 to 3000K. Solace and Iris publish no kelvin figure. **Which apps keep text and links readable at deep red?** At a plain red setting, blue and green are switched off, so blue links and icons go black. Atapa's Readable red folds blue and green into red below 1500K so they stay visible at 500K. We found no other app on this list that describes a comparable mode as of 2026-10-29. Night Shift has no red setting at all. **Which apps use the network?** Atapa has no network code at all: no account, no update check, no analytics; the licence key is checked on the Mac. Sundown says zero telemetry on its site. CircadianShield sends anonymous usage statistics, off by default. f.lux does a daily update check, per Sundown's blog. Iris activates its licence online. Solace does not state it. All checked 2026-10-28 and 2026-10-29. **What does each app cost?** f.lux and Night Shift are free. Solace is $4.99 once. Atapa is $12 once for all of your own Macs, with a 14-day trial and a 14-day refund. CircadianShield is $47 once for up to 2 computers with no free trial and a 30-day refund. Sundown is $79 lifetime, $39 a year or $4.99 a month with a 7-day trial that asks for a card. Iris is about $2 a month or $10 to $15 licences; its pricing page moved. Prices read 2026-10-28 and 2026-10-29. **Why is Atapa first only in some columns?** Because that is where it leads: the M5 Pro built-in display, readable deep red, dimming below the lowest brightness step, and no network code. f.lux is free and runs on Windows. Night Shift needs no install. Sundown has a far larger guide library and more customization. CircadianShield runs on Windows and has a melanopic dashboard. Solace bundles dark mode and wallpapers. Iris has deeper presets. ### Sources - f.lux (justgetflux.com), Mac version 42.2 seen on our M5 Pro: https://justgetflux.com (read 2026-10-29) - f.lux forum, topic 8639: https://forum.justgetflux.com/topic/8639 (read 2026-10-29) - Apple Support: Use Night Shift on your Mac: https://support.apple.com/en-us/ht207513 (read 2026-10-28) - Sundown (trysundown.com): https://trysundown.com (read 2026-10-29) - Sundown blog (comparison posts, flicker-free mode description): https://trysundown.com/blog (read 2026-10-28) - CircadianShield (circadianshield.com): https://circadianshield.com (read 2026-10-28) - Solace by Theodore HQ: https://theodorehq.com/solace (read 2026-10-28) - Iris (iristech.co): https://iristech.co (read 2026-10-28) - Apple Developer Forums, thread 819331 (FB22273730): https://developer.apple.com/forums/thread/819331 (read 2026-10-29) - Gloam on GitHub (free, open source): https://github.com/Que-tin/gloam (read 2026-10-28) ## How to make a Mac screen darker than the minimum brightness URL: https://atapa.app/guides/make-mac-screen-darker-than-minimum/ Updated: 2026-10-29 The brightness keys stop at the lowest backlight step the hardware allows, which on a MacBook Pro is still bright at night. macOS goes a little lower with Reduce white point. Atapa dims below that step in the display pipeline, to a floor of 5% by default. Checked on macOS 27.2 on 29 October 2026. At night the lowest step of the brightness keys is still bright. This guide covers what macOS can do on its own, what Atapa adds, and the limits that no software gets around. ## Why the brightness keys stop The keys control the backlight, and the panel has a lowest backlight level set by its firmware. Below that, pressing the key does nothing. To go darker you have to reduce the picture itself as well, which is a different stage of the display pipeline. On M5 Pro and M5 Max MacBook Pros there is one more wrinkle: apps that dim through a gamma table report success and change nothing (an Apple bug, still open on macOS 27.2 as of 26 October 2026; the details are on [the M5 page](/m5/)). Sundown's blog describes its flicker-free mode as dimming through the gamma table. Atapa does not use that path, so its dimming works there. ## Option 1: Reduce white point, built into macOS 1. Open System Settings, Accessibility, Display. 2. Turn on Reduce white point and move its slider. The screen gets dimmer than the keys allow. It is a fixed amount, it has no schedule, and it does not change color. It is free and already installed, so try it first. If it is enough, you are done. ## Option 2: Atapa's dim slider 1. Install Atapa and open the popover from the menu bar. 2. Drag the lower slider, the one with the sun icon, to the left. The number next to it is the brightness; the screen goes darker than the keys allow as you pass the hardware minimum. 3. To go back, drag it right, or click Back to Sunset to drop the hold and follow the evening again. The screen never goes darker than the dim floor, 5% by default. You can set it from 1% to 30% in Settings, Comfort, Dimming and red, Dim floor. Hold ⌥⌘T to see true color and full brightness while the keys are down. ⌃⌥⌘⌫ resets everything. ![Atapa's popover: the warmth slider with a flame icon above a brightness slider with a sun icon, reading 100%, and the Gentle, Warm and Deep red control below.](/renders/popover-light.webp) Atapa is our app: $12 once for all of your own Macs, with a 14-day trial that asks for no card. Dimming keeps working after the trial; deep red needs a key. ## Option 3: let the brightness keys drive Atapa's dimming 1. Open Atapa's Settings, Comfort, Backlight. 2. Set Brightness keys to Atapa dim. The default, Automatic, hands the keys to Atapa only while Steady backlight is on; System backlight leaves them to macOS. 3. Grant the Accessibility permission when asked. Atapa needs it only to intercept the keys; the tint itself asks for nothing. The Open Settings button takes you to System Settings, Privacy & Security, Accessibility. With Atapa dim, each press of the brightness keys moves Atapa's dimming by 5% instead of the backlight, so the keys reach below the hardware minimum. A small brightness pop-up shows the level; turn it off with Show the brightness HUD if you prefer. ![Atapa's Comfort settings pane: Dim floor 5%, Red style Readable red, Rest your eyes, and the Backlight section with Steady backlight, Backlight level and Brightness keys set to Automatic.](/renders/settings-comfort-light.webp) ## Option 4: let the evening do it You do not have to touch a slider every night. Atapa's bedtime question sets a curve that dims as it warms: warming starts 30 minutes before sunset, the deepest stop comes an hour before your bedtime, and daylight is back by wake-up. The built-in presets pair warmth with brightness: Candle is 1900K at 90%, Ember 1200K at 80%, Midnight 500K at 70%. Wind down in the popover jumps to tonight's deepest stop. ## Option 5: a Shortcut, a URL or the command line The Set Brightness action takes Percent (1 to 100). From a script, `open "atapa://set?dim=20"` holds 20%, and `/Applications/Atapa.app/Contents/MacOS/Atapa --set-dim 20` does the same. A Sleep Focus can also set the screen through Atapa's Focus filter. The full list is on [the Shortcuts reference](/shortcuts/). Follow My Evening, or the popover's Back to Sunset, drops the hold. ## What no software can do The MacBook Pro backlight uses PWM at every brightness level. Dimming reduces flicker at low brightness; it does not eliminate it, and no app, Atapa included, makes the panel flicker-free. Atapa's Steady backlight option (Settings, Comfort, Backlight) keeps the backlight at a level you choose and dims with color instead, which avoids the lowest backlight steps if those bother you. It is a preference, not a flicker claim. If you use it, turn off Automatically adjust brightness in System Settings, Displays, so macOS stops moving the backlight. External monitors: Atapa's pixel dimming works on any display it tints. Hardware dimming over DDC is in the app and fails soft when a monitor does not answer, but it is not yet verified on a real monitor as of 2026-10-29. Until this page says otherwise, treat that path as unproven. Intel Macs are not supported in Atapa 1.0. Reduce white point works there. ### Questions **Why does my MacBook not go darker than the lowest brightness step?** The brightness keys and the slider in System Settings control the backlight, and the panel's firmware sets a lowest backlight level. Below that the keys do nothing. Going darker means reducing the picture as well as the backlight: that is what Reduce white point does in macOS, and what Atapa's dim stage does with finer control and a schedule. **Can macOS do it without any app?** Partly. System Settings, Accessibility, Display, Reduce white point lowers the intensity of bright colors with a slider. It is a fixed amount, it has no schedule, and it does not change color. It is free and already installed, so try it first. If you want it to follow the evening, go lower, or warm the screen at the same time, that is what Atapa adds. **How low does Atapa go?** To the dim floor, 5% by default, adjustable from 1% to 30% in Settings, Comfort, Dim floor. The floor is the darkest the screen can ever get, so you cannot dim yourself into a black screen by accident. Hold ⌥⌘T to see true color and full brightness at any time, and ⌃⌥⌘⌫ resets everything. **Does dimming in software stop the backlight flicker?** No. The MacBook Pro backlight uses PWM at every brightness level, so flicker is reduced at low brightness, not eliminated, and no software removes it. Atapa's Steady backlight option keeps the backlight at a fixed level and dims with color instead, which avoids the lowest backlight steps; it does not make the panel flicker-free, and we do not claim that. **Does it work on an external monitor?** The pixel dimming works on any display Atapa tints. Hardware dimming of an external monitor over DDC is in the app and fails soft if the monitor does not answer, but it is not yet verified on a real monitor as of 2026-10-29. Treat the external-monitor hardware path as unproven until this page says otherwise. ### Sources - Apple Developer Forums: why gamma-table dimming does not apply on M5 Pro and M5 Max: https://developer.apple.com/forums/thread/819331 (read 2026-10-29) - Sundown blog (its flicker-free mode is described as dimming through the gamma table): https://trysundown.com/blog (read 2026-10-28) ## Night Shift not warm enough? What to do, step by step URL: https://atapa.app/guides/night-shift-not-warm-enough/ Updated: 2026-10-29 Night Shift's warmest step, More Warm, is a mild orange: Apple publishes no figure, and independent measurements put it around 2700 to 3000K. It still works on M5 Macs. To go warmer, or to deep red that stays readable, Atapa continues to 500K and dims below the lowest brightness step. Checked on an M5 Pro, macOS 27.2, 29 October 2026. Night Shift works, and it is the right first step. This guide starts by making sure you have all of it, then covers what to do when all of it is not enough. ## Step 1: push Night Shift all the way 1. Open System Settings, Displays, and click Night Shift. 2. Set Schedule to Sunset to Sunrise, or turn on "Turn on until tomorrow" to try it now. 3. Drag Color temperature all the way to More Warm. That is as warm as Night Shift goes. Apple does not publish a kelvin figure; independent measurements put More Warm around 2700 to 3000K, about a tungsten bulb. On our 14-inch M5 Pro, macOS 27.2, on 29 October 2026, it was a mild orange and never red. There is no hidden setting beyond the slider. ![macOS Night Shift settings on our M5 Pro on 2026-10-29: Schedule Off, "Turn on until tomorrow" on, and the Color temperature slider at More Warm.](/evidence/nightshift-m5pro-2026-10-29.webp) ## Step 2: check whether a dark room is the real problem If the screen looks fine at 19:00 and too bright at 23:00, color is only half of it. Night Shift does not dim. The brightness keys stop at the panel's lowest backlight step, which is still bright in a dark room. System Settings, Accessibility, Display, Reduce white point goes a little lower for free. Going darker still, on a schedule, is covered in [the guide to a screen darker than the minimum](/guides/make-mac-screen-darker-than-minimum/). ## Step 3: go warmer than Night Shift with Atapa Atapa is our app. It is $12 once for all of your own Macs, with a 14-day trial that asks for no card. 1. Download Atapa and open it. Setup asks one question: when do you usually go to bed? The default is 23:00. 2. Pick an intensity in the popover: Gentle ends the night at 1900K, Warm at 1200K, Deep red at 500K. Warm is the default. All three are warmer than Night Shift's More Warm. 3. Leave it. Warming starts 30 minutes before sunset, the deepest stop comes an hour before your bedtime, and daylight is back by wake-up. To see tonight's deepest stop right now, click Wind down. Hold ⌥⌘T to see true color for a moment. ⌃⌥⌘⌫ resets everything. ![Atapa's popover at 2700K: a warm white sky header, the warmth slider in the evening range and the Gentle, Warm and Deep red control below.](/renders/popover-2700K-light.webp) ## What each stop looks like Simulated with Atapa's own color math, on a P3 panel model, at 100% brightness. The last column is Atapa's estimate of melanopic light against an untouched screen; the method is on [the science page](/science/). | Stop | White point | Melanopic light, less than untouched | Compared with Night Shift | |---|---|---|---| | 3400K, Evening preset | #FFCA86 | 66% | Cooler than More Warm | | 2700K | #FFB359 | 80% | About Night Shift's More Warm | | 1900K, Gentle | #FF8B00 | 93% | Warmer; amber | | 1200K, Warm | #FF4F00 | 98% | Deep orange, Readable red partly in | | 500K, Deep red | #FF0000 | 100% | Deep red, links still visible | ![A web page at 2700K, simulated with Atapa's own color math: warm white background, dark text, blue links still blue.](/frames/screen-2700.webp) *Simulated with Atapa's own color math.* ![The same page at 500K with Readable red, simulated with Atapa's own color math: red on black, the text sharp and the links visible as a darker red.](/frames/screen-500.webp) *Simulated with Atapa's own color math.* ## If you are on an M5 Pro or M5 Max Night Shift still works on these Macs. f.lux and other apps that tint through a gamma table do not: macOS accepts the table and never applies it (an Apple bug, still open on macOS 27.2 as of 26 October 2026). On our M5 Pro on 29 October 2026, f.lux 42.2 said it was on and the panel did not change, Sundown 1.6.4 showed its own notice that warming is not available on this Mac yet, and Atapa went to 500K. Atapa tints in the display pipeline, not through the gamma table. The one-minute check and the sources are on [the M5 page](/m5/). ## Keep Night Shift on or off? Either. Atapa does not switch Night Shift off, and it shows a tip in Settings, Comfort, Prompts and tips, when both are on. If you let Atapa run the evening, Night Shift adds nothing at the deep stops and you can leave its schedule as it was. ## Readable red, not just red A plain red filter switches blue and green off, so links and icons go black. Below 1500K Atapa folds those channels into red instead, so at 500K a blue link is still a visible darker red and the text is sharp. If you want the plain filter, Settings, Comfort, Red style offers Pure red. The details and the numbers are on [the Readable red page](/readable-red/). ## After the trial Atapa never stops working. Days 1 to 14 are the trial. Days 15 to 28 are the full app with a banner. From day 29 without a key, warmth stops at 2700K, about Night Shift's warmest, while dimming, the evening curve and Shortcuts keep working. Deep red needs a licence, $12 once for all of your own Macs. Intel Macs are not supported in 1.0. ### Questions **How warm does Night Shift go?** Apple does not publish a kelvin value. Independent measurements put the More Warm end of the slider around 2700 to 3000K, about the color of a tungsten bulb. On our 14-inch M5 Pro, macOS 27.2, on 2026-10-29, More Warm was a mild orange and never red. There is no hidden setting to push it further; the slider's right end is the limit. **Is Night Shift broken on M5 Pro?** No. Night Shift works on M5 Pro and M5 Max. It is apps that tint through a gamma table, f.lux among them, that report success and change nothing there (an Apple bug; the details are on our M5 page). On our M5 Pro on 2026-10-29, f.lux 42.2 did not change the panel and Night Shift did. If Night Shift moves the color on your Mac and f.lux does not, you are seeing that bug, not a Night Shift fault. **What is warmer than Night Shift on a Mac?** Atapa goes from 6500K to 500K and dims below the lowest brightness step. Its three evening intensities end the night at 1900K (Gentle), 1200K (Warm) and 500K (Deep red), all warmer than Night Shift's More Warm. Below 1500K, Readable red folds blue and green into red so links stay visible. f.lux reaches about 1200K with its Ember effect on Intel and M1 to M4 Macs, but not on M5 Pro or M5 Max. **Do I turn Night Shift off when I use Atapa?** You can leave it on. Atapa does not switch Night Shift off and shows a tip in Settings, Comfort, when both are running. The simplest setup is to let Atapa run the evening: its curve already starts 30 minutes before sunset and reaches its deepest stop an hour before your bedtime, and that stop is warmer than anything Night Shift reaches. **Does a warmer screen help me sleep?** We do not claim that. What the research shows is that melanopic sensitivity peaks in the blue and that evening light should be dim and low in melanopic content. A warmer, dimmer screen emits less of that light; Atapa's estimate at 2700K is about 80% less than an untouched screen, and at 500K about 100%. Whether that changes your sleep depends on much more than the screen. The science page has the sources. ### Sources - Apple Support: Use Night Shift on your Mac: https://support.apple.com/en-us/ht207513 (read 2026-10-28) - CircadianShield, Night Shift comparison (independent measurement of the warmest setting): https://circadianshield.com/vs/night-shift (read 2026-10-28) - Apple Developer Forums: the M5 Pro gamma-table thread: https://developer.apple.com/forums/thread/819331 (read 2026-10-29) ## f.lux not working on M5 Pro or M5 Max? Here's why, and what works. URL: https://atapa.app/m5/ Updated: 2026-10-29 On M5 Pro and M5 Max Macs, `CGSetDisplayTransferByTable` returns success and the screen does not change. Apple's developer forum thread 819331 documents this as FB22273730, reproduced by Apple, still unfixed as of BetterDisplay's note on 13 October 2026. f.lux, Lunar, and MonitorControl are named there. Night Shift still tints, and it stays far warmer than deep red. Atapa tints in the display pipeline instead, down to 500K, tested on a 14-inch M5 Pro running macOS 27.2 on 26 October 2026. This page is our own test, with dates and sources. We make Atapa, so read the parts about Atapa as a vendor's words. Everything else here you can check on your own Mac in a minute. ## Which Macs are affected? Apple's thread 819331 names the M5 Pro and M5 Max MacBook Pros, on the built-in display and on external displays, and the MacBook Neo on an external display. Reports for the base M5 conflict, and we have not tested one, so this page does not claim either way. On Intel Macs and on M1 through M4, gamma tables still apply and f.lux works as before. | Mac | Gamma-table apps (f.lux, Lunar and MonitorControl color tables) | Source | |---|---|---| | M5 Pro, built-in and external display | Accepted, never applied | Apple thread 819331; our test on 2026-10-26 and 2026-10-29 | | M5 Max | Accepted, never applied | Apple thread 819331 | | MacBook Neo, external display | Accepted, never applied, per the thread | Apple thread 819331 | | Base M5 | Reports conflict | Apple thread 819331; not tested by us | | M1 to M4, Intel | Applied | f.lux works there | Atapa runs on any Apple silicon Mac with macOS 14 or later. Intel Macs are not supported in 1.0. ## How do I confirm it on my Mac in one minute? 1. Open f.lux preferences and drag the Daytime slider all the way to the left. In version 42.2 it reads 2700K (Tungsten). 2. Look at a white window, for example an empty Finder window. If it stays white while f.lux says it is on, you are in the bug. 3. Open System Settings, Displays, Night Shift. Turn on "Turn on until tomorrow" and move Color temperature to More Warm. The screen should turn mildly orange. That is the whole test. Night Shift uses a different path and still moves the color. The gamma-table control does not. Do not use a screenshot to judge it: macOS composites captures separately, so a capture can look tinted while the panel in front of you is not. ![f.lux 42.2 preferences on our M5 Pro on 2026-10-29: the Daytime slider at its leftmost stop, 2700K (Tungsten), and the status line "The sun is up." The panel behind this window did not change.](/evidence/flux-m5pro-2026-10-29.webp) ## Why does the app say it succeeded? The call that sets a gamma table returns success. Reading the table back returns exactly the table that was just set. The display pipeline never applies it. So the app has no way to know; every value it can check agrees with it. On our 14-inch M5 Pro on 26 October 2026, macOS 27.2 (build 26B123), we set a deep-red 256-entry table on the built-in display. The result code was 0. The readback matched at 0, 3 and 6 seconds. The panel did not change. The result was the same on macOS 27.0.1. This is also why Atapa does not try to detect the bug from code. During setup it shows a method check and asks you to look at the screen, because the screen is the only honest readout. ## What still works today? Three things, in order of effort. **Night Shift.** Built into macOS, nothing to install. On our M5 Pro at More Warm on 29 October 2026 it was mildly orange, never red. Apple does not publish a kelvin number; independent measurements put the warmest step around 2700 to 3000K. **Atapa.** Atapa is a Mac menu bar app that warms and dims the screen from daylight (6500K) to deep red (500K) through the evening. It works on M5 Pro and M5 Max MacBook Pros, where apps that tint through a gamma table do nothing. It costs $12 once for all of your own Macs, with a 14-day trial and a 14-day refund. It has no account and no network code. It requires macOS 14 or later on Apple silicon. Kevin Hofmann makes it at SOULRISE LLC. It tints in the display pipeline, not through the gamma table, so the bug does not touch it. **BetterDisplay's non-gamma path.** Its maintainer wrote on 13 October 2026 that image adjustments now go through a compositor filter instead of the color table. That is display configuration and brightness work, not an evening schedule, and it is the right tool for that job. | App, as seen on the M5 Pro built-in display | Changes the panel? | Seen | |---|---|---| | f.lux 42.2 (the latest Mac build) | No. It says it is on; the panel does not change. Also named in Apple's thread. | 2026-10-29, macOS 27.2 | | Lunar and MonitorControl, color-table adjustments | No, named in Apple's thread | Thread 819331 | | Sundown 1.6.4 | Not available. Its own app: "Warming isn't available on this Mac yet." | 2026-10-29, macOS 27.2 | | Night Shift | Yes. Mild orange at More Warm, never red. | 2026-10-29, macOS 27.2 | | BetterDisplay | Image adjustments through a compositor filter since 2026-10-13, per its maintainer | Discussion 5217 | | Atapa 1.0 | Yes, 6500K to 500K, readable deep red | 2026-10-29, macOS 27.2 | ![macOS Night Shift settings on our M5 Pro on 2026-10-29: Schedule Off, "Turn on until tomorrow" on, and the Color temperature slider at More Warm. The panel turned mildly orange.](/evidence/nightshift-m5pro-2026-10-29.webp) ![Atapa's popover on the M5 Pro holding 500K at 70% brightness: the sky header, the warmth and brightness sliders, the Gentle, Warm and Deep red control, and the footer line "Color matrix · Apple M5 Pro".](/renders/popover-500K-light.webp) ## Does Sundown work on this bug? Sundown's own app answers. On our 14-inch M5 Pro, macOS 27.2, on 29 October 2026, Sundown 1.6.4 showed this at the top of its window: > "Warming isn't available on this Mac yet. Your Mac's display ignores the usual way apps warm the screen, so for now Sundown leaves your screen's color, brightness, Night Shift and True Tone as they are. We're working on it." ![Sundown 1.6.4 on our M5 Pro on 2026-10-29. The notice at the top reads "Warming isn't available on this Mac yet", above a Warmth slider at 2000K, a Brightness slider at 100%, and "7 days remaining".](/evidence/sundown-m5pro-2026-10-29.webp) Sundown's blog describes its flicker-free mode as dimming through the gamma table, which is the mechanism this bug ignores. They say they are working on it. We recheck after each Sundown update and date the line under What changed. Credit where it is due: Sundown has a large guide library, a Windows build in progress, and far more customization than Atapa, including key pop-up styles, a Sound Studio, panel backgrounds, ambient-light dimming and room adaptation. If you are on an M1 to M4 Mac and want those, it is a fair choice. Its 7-day trial asked for a card at checkout on 2026-10-29 ("$39/year after your 7-day trial"); Atapa's 14-day trial does not. ## Will Apple fix it? Apple's Developer Technical Support reproduced the bug. It is filed as FB22273730, with duplicates FB22273782 and FB23444164. BetterDisplay's maintainer wrote on 13 October 2026 that it was still with Apple engineering. It is open on macOS 27.0.1 and on 27.2. We retest after each macOS update, with a 10-minute look at the panel, and add a dated line under What changed at the bottom of this page. When Apple fixes it, f.lux will work on these Macs again. Atapa does not depend on the fix either way. ## Will the tint show in screenshots or on a call? Not in screenshots. With the color matrix, a capture taken during the tint shows true color: tested on 2026-10-28 on the M5 Pro, macOS 27.2, with a capture before and during a visible orange tint. The tint is applied after the point where macOS captures the image. Screen sharing uses the same capture path, so it should show true color to the other side as well. One FaceTime check is still open, and the result will be dated here. On older Macs where Atapa falls back to an overlay layer, captures do include the tint. ## Transcript of the demo video The video is still to be filmed. The words below are what it will say, and they match this page.
Read the transcript Hi, I'm Kevin. I make Atapa. This is my 14-inch MacBook Pro with the M5 Pro chip, running macOS 27.2, and it is the 29th of October 2026. I'm pointing a phone at the panel, not taking screenshots, because on this Mac a screenshot does not show what the screen is doing. First, f.lux. This is version 42.2, the latest Mac build. I open the preferences and drag the Daytime slider all the way to the left. It reads 2700K, Tungsten. f.lux says the sun is up and the setting is on. Look at the white window behind it. It is still white. Nothing happened. That is the bug. The app sets a gamma table, macOS says fine, and the display never applies it. Apple's forum thread, number 819331, has it as bug FB22273730, and Apple reproduced it. Second, Sundown. Version 1.6.4, the trial. I open it, and at the top of the window it says, I'm reading it: "Warming isn't available on this Mac yet. Your Mac's display ignores the usual way apps warm the screen, so for now Sundown leaves your screen's color, brightness, Night Shift and True Tone as they are. We're working on it." So the app tells you itself. I'll check again when they update. Third, Night Shift. System Settings, Displays, Night Shift, turn on until tomorrow, slider to More Warm. Watch the panel. It goes mildly orange. So Night Shift still works, it uses a different path. It is just not very warm. Apple does not say how warm; people who have measured it say around 2700 to 3000K. Now Atapa. I open the menu bar popover. It says Color matrix, Apple M5 Pro at the bottom. I drag the warmth slider down. 3400K, the screen is warm. 1900K, it is amber. 1200K, deep orange. 500K. Look at that. The screen is deep red, and you can still read the text, and the blue links are still there. That is Readable red: blue and green get folded into red instead of switched off. I hold Option Command T and the screen goes back to true color while I hold it. Let go, it is red again. Control Option Command Delete resets everything. If the app ever crashes, a small guard process clears the tint. That's it. f.lux and Sundown did not change this panel today. Night Shift did, mildly. Atapa did, down to 500K. Links and dates are on the page.
### Questions **Which Macs are affected by the gamma-table bug?** M5 Pro and M5 Max MacBook Pros, on the built-in display and on external displays, and the MacBook Neo on an external display, per Apple's thread 819331. Reports for the base M5 conflict and we have not tested one. On Intel and M1 to M4 Macs gamma tables still apply, so f.lux works there. Atapa runs on any Apple silicon Mac with macOS 14 or later; Intel Macs are not supported in 1.0. **How do I confirm the bug on my own Mac?** Open f.lux, drag the Daytime slider all the way left (2700K in version 42.2) and look at a white window. If the panel stays white while f.lux says it is on, you are in the bug. Then open System Settings, Displays, Night Shift, and move Color temperature to More Warm. Night Shift uses a different path and should still turn the screen mildly orange. One minute. **Why does f.lux say it is on when nothing changed?** The call that sets the gamma table returns success, and reading the table back returns the table that was just set. The display pipeline never applies it. The app cannot tell the difference, because every signal it can check agrees with it. On our M5 Pro on 2026-10-26 (macOS 27.2) a deep-red table returned code 0, read back correctly at 0, 3 and 6 seconds, and changed nothing. **What still works on an M5 Pro today?** Night Shift, which is built in and stops at a mild orange. Atapa, which tints in the display pipeline and goes to 500K. BetterDisplay's non-gamma image-adjustment path, which its maintainer added on 13 October 2026, for display configuration rather than an evening schedule. f.lux 42.2 and Sundown 1.6.4 did not change our panel on 2026-10-29. **Does Sundown work on M5 Pro?** On our 14-inch M5 Pro, macOS 27.2, on 2026-10-29, Sundown 1.6.4 showed its own message: "Warming isn't available on this Mac yet. Your Mac's display ignores the usual way apps warm the screen, so for now Sundown leaves your screen's color, brightness, Night Shift and True Tone as they are. We're working on it." We recheck after each Sundown update and date the result on this page. **Will Apple fix the M5 gamma bug?** Apple's Developer Technical Support reproduced it as FB22273730, with duplicates FB22273782 and FB23444164. BetterDisplay's maintainer wrote on 13 October 2026 that it was still with Apple engineering. It is open on macOS 27.0.1 and 27.2. We retest after each macOS update and add a dated line under What changed on this page. **Does Atapa's tint show in screenshots or on a video call?** Not in screenshots. With the color matrix, a capture taken during the tint shows true color, tested 2026-10-28 on the M5 Pro with macOS 27.2, because the tint is applied after the point where macOS captures the image. Screen sharing uses the same capture path, so it should show true color too; one FaceTime check is still open and will be dated here when done. ### Sources - Apple Developer Forums, thread 819331: CGSetDisplayTransferByTable is broken on macOS Tahoe with MacBook M5 Pro, Max and Neo (FB22273730): https://developer.apple.com/forums/thread/819331 (read 2026-10-29) - f.lux forum, topic 8640: macOS Tahoe 26 notes: https://forum.justgetflux.com/topic/8640 (read 2026-10-29) - f.lux forum, topic 8639: https://forum.justgetflux.com/topic/8639 (read 2026-10-29) - BetterDisplay discussion 5217: M5 Pro and M5 Max color table issue, compositor-filter workaround (maintainer note of 2026-10-13): https://github.com/waydabber/BetterDisplay/discussions/5217 (read 2026-10-28) - BetterDisplay discussion 5238: color table adjustments do not work on the M5 Pro built-in display: https://github.com/waydabber/BetterDisplay/discussions/5238 (read 2026-10-28) - monitor-lizard issue 30: M5 Pro, macOS 27.0.1, overlay as the replacement: https://github.com/nicholaspsmith/monitor-lizard-menubar/issues/30 (read 2026-10-28) - Apple Support: Use Night Shift on your Mac: https://support.apple.com/en-us/ht207513 (read 2026-10-28) - Sundown (trysundown.com), app version 1.6.4 trial on our M5 Pro: https://trysundown.com (read 2026-10-29) - f.lux (justgetflux.com), Mac version 42.2: https://justgetflux.com (read 2026-10-29) ## Readable red: deep red that keeps text and links visible URL: https://atapa.app/readable-red/ Updated: 2026-10-29 A plain red filter turns blue and green off, so links, icons, and syntax highlighting disappear. Readable red mixes those channels into red. At 500K there is no blue left in the tint, and the words are still there. The photos on this page are of the panel, because a screenshot of Atapa's tint stays true-color. Readable red is for people who work in the dark. Astronomers and astrophotographers at the eyepiece, who need the star chart without losing dark adaptation. Pilots on a night flight deck. Sailors on a night watch. Darkroom work. And anyone reading in bed at 23:00 who wants the screen deep red, not orange, and still wants to read the words. On every other red filter, the links and icons go black. Here they do not. ## What a plain red filter does Every red screen mode works the same way: it multiplies the green and blue channels by zero and leaves red alone. White becomes red. Black stays black. And everything that was only blue or green becomes black too. A pure blue link (sRGB 0, 0, 238) has no red in it, so it disappears. A green status dot disappears. Syntax highlighting collapses to red and black. ![A web page at 500K with a plain red filter, simulated: the headline and body text are red on black, and the blue links in the text have gone black and vanished. Simulated with Atapa's own color math.](/frames/screen-500-plain.webp) *Simulated with Atapa's own color math.* ## What Readable red does instead Readable red keeps the green and blue outputs at zero, so there is still no blue in the tint, but it moves the content of those channels into red before they are dropped. At 800K and below, the red output is 0.30 times red plus 0.45 times green plus 0.25 times blue, in linear light. Blue and green stay switched off. The weights are close to how bright each channel looks, so a blue link ends up a darker red than the white background, and a green dot ends up a mid red. The fold starts at 1500K and is complete at 800K: at 1200K it is about 39% in, at 1000K about 80%. Above 1500K the tint is an ordinary warm white point and nothing is mixed. ![The same web page at 500K with Readable red, simulated: red on black, the text sharp, and the links still visible as a darker red. Simulated with Atapa's own color math.](/frames/screen-500.webp) *Simulated with Atapa's own color math.* ## The numbers for a few colors From Atapa's own color math, applied to 8-bit sRGB inputs at 500K and re-encoded. The matrices are the ones the app sends to the display. | Color on screen | Input (sRGB) | Plain red | Readable red | |---|---|---|---| | White background | 255, 255, 255 | 255, 0, 0 | 255, 0, 0 | | Body text | 29, 29, 31 | 29, 0, 0 | 30, 0, 0 | | Pure blue link | 0, 0, 238 | 0, 0, 0 (gone) | 127, 0, 0 | | LinkedIn blue | 10, 102, 194 | 10, 0, 0 | 122, 0, 0 | | Pure green | 0, 255, 0 | 0, 0, 0 (gone) | 179, 0, 0 | | Leaf green | 52, 160, 72 | 52, 0, 0 | 119, 0, 0 | | Sky blue | 120, 180, 240 | 120, 0, 0 | 184, 0, 0 | | Black | 0, 0, 0 | 0, 0, 0 | 0, 0, 0 | Black stays black in both. The difference is everything that was blue or green: gone on the left, a shade of red on the right. ## Why the photos have to be photos A screenshot of Atapa's tint shows true color. The tint is applied in the display pipeline after the point where macOS captures the image, tested on a 14-inch M5 Pro with macOS 27.2 on 28 October 2026. That is good for sharing a screen and useless for showing the effect, so the frames on this page are simulated from the real matrices. Photographs of the panel, taken with a camera, will follow. ## How much light is left At 800K and below the white point is #FF0000: the green and blue outputs are zero. On a P3 panel, blue carries about 72% of a white screen's melanopic signal and green about 28%; red carries almost none. Atapa's evening ring therefore reads about 100% less alerting light at 500K. That is an estimate of the display's output from CIE S 026 weights, not a measurement of your eyes, and [the science page](/science/) explains what it does and does not mean. The red that remains is dim too: the Midnight preset is 500K at 70% brightness, and the dim slider goes lower. ## How to get there Three ways. Click Wind down in the popover to jump to tonight's deepest stop; with the Deep red intensity that is 500K. Choose the Midnight preset, 500K at 70%, from Settings, General. Or drag the warmth slider to the bottom. Readable red is the default; Settings, Comfort, Red style switches to Pure red if you want the plain filter. Hold ⌥⌘T to see true color for a moment, and ⌃⌥⌘⌫ resets everything. ![Atapa's popover holding 500K at 70% brightness, with the warmth slider at the bottom of its range, the ring at about 100% less alerting light, and the footer line "Color matrix · Apple M5 Pro".](/renders/popover-500K-light.webp) On an M5 Pro or M5 Max this is the only path to deep red we know of, because apps that tint through a gamma table change nothing there; the test is on [the M5 page](/m5/). On older Apple silicon Macs, Readable red works the same way. Gloam, a free open-source app, stops around 1900K; Night Shift stops at a mild orange. ### Questions **What is Readable red?** Atapa's way of reaching deep red without losing the picture. Below 1500K the screen's blue and green content is folded into the red channel instead of being switched off. At 800K and below the fold is complete: red output is 0.30 of red plus 0.45 of green plus 0.25 of blue, in linear light, and the green and blue outputs are zero. A blue link that a plain red filter turns black stays visible as a darker red. **Is there any blue light left at 500K?** The tint itself has none: the green and blue outputs of the display are zero at 800K and below, so the white point is #FF0000 and Atapa's melanopic estimate is about 100% less than an untouched screen. What remains is the red primary, which carries almost no melanopic weight on a P3 panel (about 0.04% of white's melanopic output in our model). Black stays black. **Why does the website use simulated frames and placeholders instead of screenshots?** Because a screenshot of Atapa's tint shows true color. The tint is applied in the display pipeline after the point where macOS captures the image, tested on an M5 Pro with macOS 27.2 on 2026-10-28. The frames here are simulated with Atapa's own color math from the real matrices. Panel photos, taken with a camera pointed at the screen, are marked as not yet taken until they exist. **Who needs red that stays readable?** Anyone who works in the dark and needs to see the screen without losing dark adaptation or waking up: astronomers and astrophotographers at the eyepiece, pilots on a night flight deck, sailors on a night watch, darkroom work, and anyone reading in bed at 23:00. In every case a plain red filter that turns links and icons black is the problem Readable red solves. **Can I turn it off and get a plain red instead?** Yes. Settings, Comfort, Red style offers Readable red or Pure red. Pure red scales the channels only, which is what every other red filter does; pure-blue content goes black. Readable red is the default. The Midnight preset is 500K at 70% brightness, and Wind down jumps to tonight's deepest stop with one click. ### Sources - CIE S 026:2018, the melanopic weighting behind the "about 100% less" estimate: https://cie.co.at/publications/cie-system-metrology-optical-radiation-iprgc-influenced-responses-light-0 (read 2026-10-27) - Gloam on GitHub, a free open-source Mac warmth app that stops around 1900K: https://github.com/Que-tin/gloam (read 2026-10-28) ## Evening light and your body clock: what a screen can and can't do URL: https://atapa.app/science/ Updated: 2026-10-29 A screen's effect on the body clock is mostly melanopic light, not a "blue light" percentage. On a P3 panel, about 72% of that signal is in the blue channel and about 28% is in the green; red contributes almost none (CIE S 026 weights, applied in `docs/RESEARCH.md` §13). Warming helps. Dimming helps too, because the same spectrum at a lower luminance is less alerting. Atapa's evening ring is that estimate against an untouched screen. It is not a sleep measurement, and we do not claim one. This page explains the one number Atapa shows about light, how it is computed, and where it stops. It is written by the people who make Atapa, and it makes no claim about your sleep. ## What is melanopic light, in plain words? Your retina has a small set of cells that do not help you see shapes. They measure how bright the world is and report it to the body clock. Their pigment, melanopsin, is most sensitive to light around 480 nm, in the blue, and much less sensitive to red. Light weighted by that sensitivity is melanopic light. CIE S 026:2018 is the international standard that defines the weighting, and Lucas et al. 2014 is the paper that argued for measuring light this way instead of by lux alone. So the question for a screen in the evening is not "how much blue light does it block" but "how much melanopic light does it emit". The first has no shared method; the second has a standard. ## Why blue is about 72% and green about 28% A white screen is three primaries added together. To know how much of its melanopic output each channel carries, you weight each primary's spectrum by the CIE S 026 melanopic function and by the primary's share of white luminance. For an Apple-style P3 panel we modelled a 450 nm blue LED, a 533 nm green phosphor and KSF red lines at 613, 631 and 648 nm, with P3 luminance shares of 0.229, 0.692 and 0.079. The melanopic-to-luminance ratios come out at 0.0023 for red, 0.614 for green and 13.57 for blue, and the channel shares at: | Channel | Share of a white P3 screen's melanopic output | |---|---| | Blue | 0.717 | | Green | 0.283 | | Red | 0.0004 | Broader P3 primaries give 0.000, 0.313 and 0.686. An sRGB white-LED monitor gives 0.004, 0.252 and 0.743. The split moves a few points between displays, which is why the app always says "about" and "estimate". It replaced an earlier guess that weighted green at 10% and overstated the effect; green matters more than the "blue light" framing suggests. ## Why dimming matters as much as warmth Warming a screen removes blue and green. Dimming it removes everything in proportion. Melanopic light scales with luminance, so the same spectrum at half the brightness is half the melanopic output. The two effects multiply: a warm, dim screen emits far less than a warm, bright one. That is why Atapa's evening curve dims as it warms, and why it can dim below the lowest brightness step of the hardware. It is also why a mild orange at full brightness, which is what Night Shift gives at More Warm, still leaves a lot of melanopic light on the screen. ## What the ring estimates Atapa's popover shows one ring: "about x% less alerting light". It is the melanopic estimate for the current tint against an untouched screen, from the linear output multipliers for warmth, Readable red and dimming. In Statistics it is tracked per evening, from 18:00 to 06:00; time with the tint off counts as 100%, and a sleeping display is not counted. At 100% brightness, Atapa's own color math gives these reductions. Each value is simulated with Atapa's own color math on the P3 panel model, not measured on your display. | Warmth | White point on the screen | Melanopic light, less than an untouched screen | |---|---|---| | 6500K | #FFFFFF | 0% | | 5500K | #FFF4E2 | 20% | | 5000K | #FFECD1 | 31% | | 4300K | #FFE0B4 | 46% | | 3400K | #FFCA86 | 66% | | 3000K | #FFBE6E | 74% | | 2700K | #FFB359 | 80% | | 2300K | #FFA139 | 87% | | 1900K | #FF8B00 | 93% | | 1500K | #FF6D00 | 96% | | 1200K | #FF4F00 | 98% | | 1000K | #FF3100 | 99% | | 800K and below, Readable red | #FF0000 | 100% | Dimming multiplies the remainder. At 2700K and 90% brightness, the remainder is 0.20 times 0.9, so the ring reads about 82% less. At 500K with Readable red the estimate reaches about 100%, because the green and blue outputs are zero; the small red output carries almost no melanopic weight. Night Shift's warmest step, around 2700 to 3000K by independent measurement, lands near the 74 to 80% rows at full brightness. ![Atapa's popover holding 500K with the ring showing about 100% less alerting light now and 62% less so far this evening.](/renders/popover-500K-light.webp) ## What the research does not show The papers below show that melanopsin drives the body clock, that its sensitivity peaks in the blue, and that evening light should be dim and low in melanopic content. Brown et al. 2022 give a recommendation for the three hours before bed in melanopic terms. Cajochen et al. 2011 found that an LED-backlit screen in the evening affected circadian physiology and alertness compared with a less blue screen. Spitschan 2019 reviews what melanopsin does and does not contribute. None of that is a study of Atapa, and we have not run one. We do not claim that Atapa improves sleep, raises melatonin, or is medically proven. We do not publish a "blue light blocked" percentage, because the figures on vendor sites share no method. We do not claim to remove PWM flicker: the backlight of a MacBook Pro flickers in hardware, and no software changes that. What we claim is narrower: Atapa reduces the screen's melanopic output, by about the amounts in the table, as an estimate. ## Sources, and what each one says 1. CIE S 026:2018 defines the melanopic weighting function and the five alpha-opic quantities. It is the standard behind the 72/28/0 split. 2. Lucas et al. 2014, Trends in Neurosciences, argues for measuring light by its melanopic content rather than by lux alone, and supplies the toolbox that later work uses. 3. Brown et al. 2022, PLOS Biology, is a consensus recommendation for indoor light across the day: bright and melanopic-rich in the daytime, dim and low in melanopic content in the evening and at night. 4. Cajochen et al. 2011, Journal of Applied Physiology, is an evening-screen study: an LED-backlit screen with more blue affected circadian physiology and cognitive performance compared with a less blue screen. 5. Spitschan 2019, Current Opinion in Behavioral Sciences, reviews melanopsin's contributions to both non-visual and visual function and where the evidence is still open. ### Questions **What is melanopic light?** Light weighted by how strongly it drives melanopsin, the pigment in the retinal cells that report brightness to the body clock rather than form images. Melanopsin's sensitivity peaks in the blue, near 480 nm, and falls off toward red. CIE S 026:2018 defines the weighting. A screen's melanopic output is what matters for the clock, more than a "blue light" percentage that no two vendors compute the same way. **Why does Atapa weight blue at 72% and green at 28%?** Because that is each channel's share of a white P3 screen's melanopic output when you weight the three primaries' spectra by the CIE S 026 melanopic function and by their luminance share. Our model of an Apple-style P3 panel gives red 0.0004, green 0.283, blue 0.717. Broader P3 primaries give 0.000, 0.313, 0.686, and an sRGB white-LED monitor 0.004, 0.252, 0.743, which is why the ring says about. **Does dimming help as much as warming?** Melanopic light scales with luminance, so halving brightness halves the melanopic output at any color. Warming removes blue and green; dimming removes everything in proportion. The two multiply. At 2700K at 100% brightness Atapa's estimate is about 80% less melanopic light than an untouched screen; at 90% brightness it is about 82%. That is why Atapa dims through the evening as well as warming. **What does Atapa's evening ring show?** An estimate of how much less melanopic light the screen gave off this evening compared with the same screen untouched, from 18:00 to 06:00, using the output multipliers for warmth, Readable red and dimming at each moment. Time with the tint off counts as 100%, and a sleeping display is not counted. It is computed from the display's output, not from your eyes or your sleep. **Will Atapa help me sleep?** We do not claim that. The research shows that melanopic sensitivity peaks in the blue and that evening light should be dim and low in melanopic content; Brown et al. 2022 recommend a low melanopic level in the three hours before bed. Whether a warmer, dimmer screen changes your sleep depends on much more than the screen, and no study of Atapa exists. Atapa reduces the screen's melanopic output. That is the whole claim. **What percentage of blue light does Atapa block?** We do not publish one, because "blue light blocked" has no shared method and the figures on vendor sites cannot be compared. What we publish is the melanopic estimate with its method: at 2700K about 80% less, at 1900K about 93%, at 500K with Readable red about 100%, because the green and blue outputs are zero. Those are estimates of the display's output on a P3 panel model. ### Sources - CIE S 026:2018, CIE System for Metrology of Optical Radiation for ipRGC-Influenced Responses to Light: https://cie.co.at/publications/cie-system-metrology-optical-radiation-iprgc-influenced-responses-light-0 (read 2026-10-27) - Lucas et al. 2014, Measuring and using light in the melanopsin age, Trends in Neurosciences: https://doi.org/10.1016/j.tins.2013.10.004 (read 2026-10-29) - Brown et al. 2022, Recommendations for daytime, evening, and nighttime indoor light exposure to best support physiology, sleep, and wakefulness in healthy adults, PLOS Biology: https://doi.org/10.1371/journal.pbio.3001571 (read 2026-10-29) - Cajochen et al. 2011, Evening exposure to a light-emitting diodes (LED)-backlit computer screen affects circadian physiology and cognitive performance, Journal of Applied Physiology: https://doi.org/10.1152/japplphysiol.00165.2011 (read 2026-10-29) - Spitschan 2019, Melanopsin contributions to non-visual and visual function, Current Opinion in Behavioral Sciences: https://doi.org/10.1016/j.cobeha.2019.06.004 (read 2026-10-29) ## Atapa Shortcuts actions, Focus filter, URL scheme and CLI: the reference URL: https://atapa.app/shortcuts/ Updated: 2026-10-29 Atapa for Mac ships 9 Shortcuts actions (Wind Down, Show True Color, Follow My Evening, Set Evening Intensity, Set Warmth, Set Brightness, Apply Preset, Turn Atapa On or Off, Get Atapa State), a Focus filter, the atapa:// URL scheme and a command line, all on the Mac with no network. This matches version 1.0 as of 29 October 2026. Everything on this page runs on the Mac, talks to the running app, and needs no account. Atapa has to be running for any of it to do anything; the actions report "Atapa is not running." otherwise. ## Shortcuts actions Nine actions appear in the Shortcuts app and in Spotlight once Atapa has launched once. | Action | Parameters | What it does | |---|---|---| | Wind Down | Wind down (on or off; leave empty to switch) | Goes to tonight's deepest stop right away, or back to your evening | | Show True Color | Minutes (1 to 1440, default 15) | Removes the warmth for a while, for photos or video; it comes back by itself | | Follow My Evening | none | Drops wind down, true color and manual changes, and returns to the evening curve | | Set Evening Intensity | Intensity: Gentle, Warm or Deep red | Sets how warm the night gets: 1900K, 1200K or 500K at the deepest stop | | Set Warmth | Kelvin (500 to 6500); Brightness % (1 to 100, optional) | Holds the screen at that warmth, and brightness if given | | Set Brightness | Percent (1 to 100) | Dims below the lowest backlight level; 100 is no dimming | | Apply Preset | Preset (one of yours, e.g. Midnight) | Holds that preset's warmth and brightness | | Turn Atapa On or Off | On (on or off; leave empty to switch) | Turns the warm screen on or off | | Get Atapa State | none | Returns text: on or off, warmth, brightness, and what Atapa is doing, e.g. "on · 1200K · brightness 80% · Sunset" | Set Evening Intensity works on the plan the bedtime question creates. If you tuned the curve by hand in Settings, the action reports "Your evening curve was tuned by hand. Change the intensity in Atapa's Settings." instead of guessing. Four actions also answer Siri: "Wind down with Atapa", "Show true color with Atapa", "Follow my evening with Atapa", and "Toggle Atapa" or "Turn Atapa on or off". ## Focus filter Atapa adds one Focus filter, "Set Atapa's screen", with one choice, Screen: | Screen | While the Focus is on | |---|---| | Deep red (wind down) | Tonight's deepest stop | | True color | No warmth | | Follow my evening (left empty) | Nothing changes | When the Focus ends, whatever the filter changed is undone and your evening comes back. Sleep Focus to deep red is the obvious pairing; Photo editing or Gaming to true color is the other. Set it in System Settings, Focus, the Focus you want, Focus filters, Add filter, Atapa. ## URL scheme Any app that can open a URL can drive Atapa, including Shortcuts, Keyboard Maestro, Raycast, Alfred and a terminal with `open`. | URL | Effect | |---|---| | `atapa://set?kelvin=1200&dim=80` | Hold 1200K at 80% brightness; either parameter may be left out | | `atapa://preset/Midnight` | Apply the preset named Midnight (also `atapa://preset?name=Midnight`) | | `atapa://toggle` | Turn Atapa on or off | | `atapa://reveal` | Toggle true color (the hotkey's hold behavior, as a switch) | | `atapa://winddown` | Wind down, or back to the evening if already winding down | | `atapa://truecolor?minutes=30` | True color for 30 minutes (default 15, up to 1440) | | `atapa://evening` | Follow my evening: drop every hold | `dim` accepts 0 to 1 or 1 to 100; 80 and 0.8 mean the same. Preset names match without regard to case. From a terminal: ``` open "atapa://set?kelvin=1200&dim=80" ``` ## Command line The app binary forwards a command to the running app and exits, printing "sent to Atapa: …". The path is `/Applications/Atapa.app/Contents/MacOS/Atapa`. | Flag | Effect | |---|---| | `--set-kelvin 1200` | Hold 1200K | | `--set-dim 80` | Hold 80% brightness (0 to 1 or 1 to 100) | | `--preset Midnight` | Apply the preset named Midnight | | `--toggle` | Turn Atapa on or off | | `--reveal` | Toggle true color | | `--wind-down` | Wind down, or back if already winding down | | `--true-color 30` | True color for 30 minutes (default 15) | | `--follow-evening` | Drop every hold and follow the evening curve | ``` /Applications/Atapa.app/Contents/MacOS/Atapa --preset Midnight ``` ## Keyboard shortcuts Recorded in Settings, Shortcuts. These are the defaults in 1.0; click a field to change one, Delete clears it. | Shortcut | Default | What it does | |---|---|---| | Reveal true color | ⌥⌘T, hold | True color while the keys are held; Reveal behavior can be set to toggle | | Toggle Atapa | ⌃⌥⌘B | On or off | | Warmer | ⌃⌥⌘→ | One warmth step warmer (250K by default) | | Cooler | ⌃⌥⌘← | One warmth step cooler | | Dimmer | ⌃⌥⌘↓ | One dim step darker (5% by default) | | Brighter | ⌃⌥⌘↑ | One dim step brighter | | Next preset | ⌃⌥⌘P | Steps through the presets in the order shown in Settings, Presets | | Emergency reset | ⌃⌥⌘⌫ | Restores true color and drops every hold; cannot be changed | ![Atapa's Shortcuts settings pane: Reveal true color ⌥⌘T with Reveal behavior Hold, Toggle Atapa ⌃⌥⌘B, and Warmer, Cooler and Dimmer with their default combinations.](/renders/settings-shortcuts-light.webp) The emergency reset is the escape to remember. If the screen is ever stuck tinted, ⌃⌥⌘⌫ clears it; if Atapa is force-quit or crashes, a small guard process bundled with the app clears the tint on its own. ## Brightness keys The keyboard's brightness keys can drive Atapa's dimming below the hardware minimum. Settings, Comfort, Backlight, Brightness keys offers Automatic, Atapa dim and System backlight. With Atapa dim, each press moves Atapa's dimming by 5% instead of the backlight; Automatic does that only while Steady backlight is on. Intercepting the keys needs the Accessibility permission, which Atapa asks for only when you choose that; the tint itself needs no permission. ## Modes, for power users The bedtime question sets everything most people need. Under the hood Atapa has three modes in Settings, Schedule: Sunset (the default, driven by the sun and your bedtime), Schedule (fixed times instead of the sun) and Manual (hold whatever the sliders say). Set Warmth, Set Brightness, Apply Preset and the URL scheme's `set` all create a manual hold; Follow My Evening, `atapa://evening` or the popover's Back to Sunset button drop it. ### Questions **How do I make a Sleep Focus turn the screen deep red?** Open System Settings, Focus, Sleep, and under Focus filters add Atapa's filter, "Set Atapa's screen". Choose "Deep red (wind down)". When Sleep comes on, the screen goes to tonight's deepest stop; when it ends, Atapa goes back to your evening curve. The same filter set to "True color" suits a Photo editing or Gaming Focus. No Shortcut is needed. **Can I set an exact kelvin and brightness from a Shortcut?** Yes. The Set Warmth action takes Kelvin (500 to 6500) and an optional Brightness % (1 to 100) and holds the screen there. Set Brightness takes Percent (1 to 100) alone; 100 means no dimming. From a script, open atapa://set?kelvin=1200&dim=80, or run /Applications/Atapa.app/Contents/MacOS/Atapa --set-kelvin 1200. Follow My Evening drops the hold again. **What does the URL scheme accept?** atapa://set?kelvin=1200&dim=80, atapa://preset/Midnight, atapa://toggle, atapa://reveal, atapa://winddown, atapa://truecolor?minutes=30 and atapa://evening. Open one with the open command or from any app that can open a URL. dim accepts 0 to 1 or 1 to 100. Preset names are matched without regard to case. **Is there a command line?** Yes. The app binary forwards flags to the running app: --set-kelvin 1200, --set-dim 80, --preset Midnight, --toggle, --reveal, --wind-down, --true-color 30 and --follow-evening. The path is /Applications/Atapa.app/Contents/MacOS/Atapa. It prints "sent to Atapa" and exits; Atapa must already be running. **What are the keyboard shortcuts?** Hold ⌥⌘T to see true color while the keys are down. ⌃⌥⌘B toggles Atapa. ⌃⌥⌘→ and ⌃⌥⌘← go warmer and cooler by 250K, ⌃⌥⌘↓ and ⌃⌥⌘↑ dim and brighten, ⌃⌥⌘P steps to the next preset. ⌃⌥⌘⌫ is the emergency reset and cannot be changed. The rest are recorded in Settings, Shortcuts. **Does Control Center have an Atapa control?** Through a Shortcut. Add any Atapa action to a Shortcut, then add that Shortcut to Control Center or the menu bar from the Shortcuts app. A native Control Center control is on the list for later. Siri phrases also work: "Wind down with Atapa", "Show true color with Atapa", "Follow my evening with Atapa", "Toggle Atapa". ### Sources - Apple Support: Use Night Shift on your Mac (the built-in schedule and Control Center toggle, for comparison): https://support.apple.com/en-us/ht207513 (read 2026-10-28) ## Atapa vs CircadianShield: Mac and Windows at $47, or Mac only at $12? URL: https://atapa.app/vs/circadianshield/ Updated: 2026-10-29 Choose CircadianShield if you want one licence for Mac and Windows and a dashboard that reports melanopic light. Choose Atapa if you are on an M5 Pro or M5 Max, or want readable deep red at 500K for $12 once. CircadianShield's own site said on 28 October 2026 that M5 has not been tested yet; its warmest setting is 1800K. CircadianShield is a paid-once warmth app for Mac and Windows that leads with melanopic light, which is the right thing to lead with. This page is about where the two apps differ, with the date each fact was read. ## Side by side | Criterion | CircadianShield | Atapa | |---|---|---| | Price | $47 once, up to 2 computers; no free trial; 30-day refund (2026-10-28) | $12 once, all of your own Macs; 14-day trial without a card; 14-day refund | | Platforms | macOS 14 and 15 on M1 through M4 Max, and Windows 10 or later (2026-10-28) | macOS 14 or later, Apple silicon; Intel not supported in 1.0 | | M5 Pro | "M5 has not been tested yet", its own site (2026-10-28) | Works, 6500K to 500K on our M5 Pro (2026-10-29, macOS 27.2) | | Warmest | 1800K (2026-10-28) | 500K | | Readable red | Not described (2026-10-28) | Yes, below 1500K | | Dims below the lowest brightness step | Not described (2026-10-28) | Yes, 5% floor by default | | Melanopic figure | Dashboard | One evening ring, an estimate | | Automation | Not listed (2026-10-28) | Shortcuts, Focus filter, URL scheme, CLI | | Network use | Anonymous usage statistics, off by default (2026-10-28) | No network code | ## Where CircadianShield leads One licence covers a Mac and a Windows PC, up to 2 computers. Its melanopic dashboard is more detailed than Atapa's single ring. Its refund window is 30 days against Atapa's 14. If you split your evenings between a MacBook and a Windows desktop, it is the only app on our comparison besides f.lux that covers both, and f.lux is free but does nothing on an M5 Pro. ## Where it stops Its warmest setting is 1800K, which is amber. Atapa's Gentle intensity ends the night at 1900K, so CircadianShield's maximum is roughly Atapa's mildest evening. Atapa's Warm and Deep red intensities go to 1200K and 500K, and from 1500K down Readable red keeps links and icons visible. On the M5 Pro and M5 Max, CircadianShield's own site says M5 has not been tested yet (read 2026-10-28). We have not installed it on our M5 Pro, so we do not say whether it works there. Atapa does: tested on a 14-inch M5 Pro, macOS 27.2, on 2026-10-29, down to 500K. The one-minute check for the M5 gamma bug is on [the M5 page](/m5/). ## Melanopic numbers, both estimates CircadianShield reports melanopic light in a dashboard. Atapa reports one ring, "about x% less alerting light", estimated from CIE S 026 weights on a P3 panel model: blue carries about 72% of a white screen's melanopic signal, green about 28%, red almost none. At 2700K and 90% brightness the ring says about 82% less than an untouched screen. Both are estimates from the display's output, not measurements of your eyes or your sleep. Atapa does not claim a sleep outcome, and [the science page](/science/) explains why. ## Privacy CircadianShield sends anonymous usage statistics, off by default. Atapa has no network code: no account, no update check, no analytics, and the licence key is an offline signed string. Both are paid once. ## Price CircadianShield is $47 once for up to 2 computers, with no free trial and a 30-day refund. Atapa is $12 once for all of your own Macs, with a 14-day trial that asks for no card and a 14-day refund. After the trial Atapa keeps working; from day 29 without a key, warmth stops at 2700K and everything else continues. ## Choose CircadianShield if You need Mac and Windows on one licence, you want a detailed melanopic dashboard, and 1800K is warm enough. If you are on an M1 through M4 Mac, its own site lists your chip as supported. ## Choose Atapa if You are on an M5 Pro or M5 Max, you want deep red at 500K that stays readable, or you want the lower price and no network code. Intel Macs are not supported in 1.0, and there is no Windows build. ### Questions **Does CircadianShield work on M5 Pro and M5 Max?** Its own site lists Apple silicon M1 through M4 Max and says M5 has not been tested yet, read on 2026-10-28. We have not installed it on our M5 Pro, so this page does not say either way. Atapa was tested on a 14-inch M5 Pro with macOS 27.2 on 2026-10-29 and changed the screen down to 500K. If CircadianShield publishes an M5 result, we will add the date here. **What does each one cost?** CircadianShield is $47 once for up to 2 computers, Mac and Windows, with a 30-day refund and no free trial, read 2026-10-28. Atapa is $12 once for all of your own Macs, with a 14-day trial that asks for no card and a 14-day refund. If you need Windows, only CircadianShield covers it. **How warm does each one go?** CircadianShield's warmest published setting is 1800K, read 2026-10-28. Atapa goes to 500K, and below 1500K it folds blue and green into red so links and icons stay visible. Atapa's three evening intensities end the night at 1900K, 1200K and 500K; the Gentle stop is close to CircadianShield's warmest. **Which one is more private?** CircadianShield sends anonymous usage statistics, off by default, per its site on 2026-10-28. Atapa has no network code at all: no account, no update check, no analytics, and the licence key is checked on the Mac with an offline signature. Both are paid once rather than by subscription. **Does either one measure melanopic light?** CircadianShield has a melanopic dashboard and builds its marketing around that figure. Atapa shows one evening ring: an estimate of melanopic light compared with an untouched screen, using CIE S 026 weights on a P3 panel model (blue about 72%, green about 28%, red almost none). Neither number is a sleep measurement, and Atapa does not claim one. ### Sources - CircadianShield (circadianshield.com): price, supported chips, warmest setting, usage statistics: https://circadianshield.com (read 2026-10-28) - CIE S 026:2018, the melanopic weighting Atapa's estimate uses: https://cie.co.at/publications/cie-system-metrology-optical-radiation-iprgc-influenced-responses-light-0 (read 2026-10-27) - Apple Developer Forums, thread 819331 (FB22273730): https://developer.apple.com/forums/thread/819331 (read 2026-10-29) ## Atapa vs f.lux: which one changes the screen on your Mac? URL: https://atapa.app/vs/flux/ Updated: 2026-10-29 Choose f.lux if you want a free warmth app on Windows or on a Mac where gamma tables still apply. Choose Atapa if you are on an M5 Pro or M5 Max, or if you want deep red at 500K with links still readable, paid once, with no network code. f.lux is named in Apple's thread as one of the apps the M5 gamma bug breaks. f.lux is the app most people reach for first, for good reasons. This page is about where the two differ, with the date on each fact. ## Side by side | Criterion | f.lux | Atapa | |---|---|---| | Price | Free, donation asked (2026-10-28) | $12 once, all of your own Macs; 14-day trial, 14-day refund | | Platforms | macOS and Windows | macOS 14 or later, Apple silicon. Intel not supported in 1.0 | | M5 Pro built-in display | No change. f.lux 42.2 said it was on; the panel did not change (2026-10-29, macOS 27.2). Named in Apple thread 819331 | Changes the screen, 6500K to 500K (2026-10-29, macOS 27.2) | | Warmest | 1900K daytime per its quick-start page; Ember about 1200K per competitor posts (2026-10-28) | 500K | | Readable red | No | Yes: blue and green folded into red below 1500K | | Dims below the lowest brightness step | No; a brightness slider is a feature request on its forum (2026-10-28) | Yes, to a 5% floor you can raise | | Shortcuts and Focus filter | No (2026-10-28) | Nine Shortcuts actions, a Focus filter, a URL scheme, a CLI | | Network use | Daily update check, per Sundown's blog (2026-10-28) | None | | Last Mac release | Version 42.2 seen 2026-10-29; last release 2023-05-17 per Sundown | 1.0, 2026-10-29 | ## Where f.lux leads It is free. It runs on Windows, so one habit covers both machines. It has a sunset schedule, a wake-up time, and color effects. On an Intel Mac or an M1 through M4 Mac it still does its job, and if that is your Mac there is no M5 reason to switch. ## Where it stops on an M5 Pro Since the M5 Pro and M5 Max, macOS accepts the gamma table that f.lux sets and never shows it (Apple bug FB22273730, open on macOS 27.2 as of 26 October 2026). The app cannot see the failure, because reading the table back returns what it set. On our 14-inch M5 Pro on 29 October 2026, f.lux 42.2 with the Daytime slider at its lowest stop, 2700K (Tungsten), said "The sun is up" and the panel stayed white. The f.lux developer is tracking the bug in the f.lux forum and waiting on Apple. ![f.lux 42.2 preferences on our M5 Pro on 2026-10-29: the Daytime slider at its leftmost stop, 2700K (Tungsten). The panel behind this window did not change.](/evidence/flux-m5pro-2026-10-29.webp) Atapa tints in the display pipeline instead of through the gamma table, so the same Mac goes from 6500K to 500K. The full test, with the one-minute check you can run yourself, is on [the M5 page](/m5/). ## Deep red that stays readable f.lux's warmest settings are orange. Atapa goes on to 500K, and from 1500K down it folds blue and green into red instead of switching them off. A pure blue link that a plain red filter would turn black stays visible as a darker red. That matters for night reading, astronomy and any dark room. The method, with simulated frames and the numbers, is on [the Readable red page](/readable-red/). ![Atapa's popover holding 500K at 70% brightness on an M5 Pro, with the footer line "Color matrix · Apple M5 Pro".](/renders/popover-500K-light.webp) ## Dimming, Shortcuts and privacy Atapa dims below the lowest brightness step of the hardware, down to a floor of 5% that you can raise in Settings, Comfort. The brightness keys can drive that dimming once you grant Accessibility. f.lux has no brightness control; a slider is a long-standing request on its forum. Atapa ships nine Shortcuts actions (Wind Down, Show True Color, Set Warmth and the rest), a Focus filter so a Sleep Focus can mean deep red, a URL scheme and a CLI. f.lux has none of these on macOS as of 2026-10-28. Atapa contains no network code: no account, no update check, no analytics, and the licence is an offline signed key. f.lux checks for updates daily, per Sundown's blog; we have not measured it. ## Price f.lux is free. Atapa is $12 once for all of your own Macs, with a 14-day trial that asks for no card and a 14-day refund. After the trial it never stops working: from day 29 without a key, warmth stops at 2700K and everything else continues. Deep red needs a key. ## Choose f.lux if You want a free app, you are on Windows, or you are on an Intel or M1 to M4 Mac and orange at sunset is what you want. It is a good app on those machines, and nothing on this page argues with that. ## Choose Atapa if You are on an M5 Pro or M5 Max and the screen has to change. Or you want deep red at 500K with links still readable, dimming below the hardware minimum, Shortcuts and a Focus filter, and an app that never touches the network. Try it free for 14 days; the trial does not ask for a card. ### Questions **Is f.lux broken on M5 Pro and M5 Max?** f.lux is named in Apple's developer thread 819331 as one of the apps affected by bug FB22273730: macOS accepts a gamma table and never applies it on those chips. On our 14-inch M5 Pro, macOS 27.2, on 2026-10-29, f.lux 42.2 said it was on and the panel did not change. The f.lux developer is tracking the bug and waiting on Apple. On Intel and M1 to M4 Macs it works as before. **Is f.lux free and is Atapa free?** f.lux is free and asks for a donation. Atapa is $12 once for all of your own Macs, with a 14-day trial that does not ask for a card and a 14-day refund. After the trial Atapa keeps working: days 15 to 28 show a banner, and from day 29 without a key warmth stops at 2700K while dimming, the evening curve and Shortcuts keep working. Deep red needs a key. **Does f.lux run on Windows? Does Atapa?** f.lux runs on Windows and macOS. Atapa is Mac only, on Apple silicon with macOS 14 or later; Intel Macs are not supported in 1.0. If you need one app on both systems, f.lux is the pick, or CircadianShield if you want a paid app with a Windows build. **How warm does each one go?** f.lux's quick-start page lists 1900K for daytime settings, and its Ember color effect is about 1200K per competitor posts. On our M5 Pro the Daytime slider read 2700K at its lowest stop in version 42.2. Atapa goes to 500K, and below 1500K it folds blue and green into red so links and icons stay visible. Both have a sunset schedule. **Does either app use the network?** Per Sundown's blog, f.lux does a daily update check; we have not measured it ourselves. Atapa has no network code at all: no account, no update ping, no analytics, and the licence key is checked on the Mac with an offline signature. The website uses Cloudflare Web Analytics; the app does not. ### Sources - f.lux (justgetflux.com), Mac version 42.2: https://justgetflux.com (read 2026-10-29) - f.lux forum, topic 8640: macOS Tahoe 26 notes: https://forum.justgetflux.com/topic/8640 (read 2026-10-29) - f.lux forum, topic 8639: https://forum.justgetflux.com/topic/8639 (read 2026-10-29) - Apple Developer Forums, thread 819331 (FB22273730): https://developer.apple.com/forums/thread/819331 (read 2026-10-29) - Sundown blog (f.lux release date and update-check note): https://trysundown.com/blog (read 2026-10-28) ## Atapa vs Iris: many presets, or one evening curve? URL: https://atapa.app/vs/iris/ Updated: 2026-10-29 Choose Iris if you want preset depth and a Windows build. Choose Atapa if you want one bedtime question, readable deep red at 500K, an offline licence and an app tested on an M5 Pro. Iris's pricing page had moved when we checked on 28 October 2026, and Sundown's posts say its Mac build has had no update since 2022. Iris is one of the older screen-warmth apps, with versions for Mac and Windows and a long list of presets and modes. Atapa is new, Mac only, and built around one evening curve. This page is about the differences, with the date each fact was read, and with two facts about Iris we could not pin down. ## Side by side | Criterion | Iris | Atapa | |---|---|---| | Price | About $2 a month or $10 to $15 licences; pricing page moved, re-check (2026-10-28) | $12 once, all of your own Macs; 14-day trial without a card; 14-day refund | | Platforms | macOS and Windows | macOS 14 or later, Apple silicon; Intel not supported in 1.0 | | M5 Pro | Not stated on its site (2026-10-28); not tested by us | Works, 6500K to 500K on our M5 Pro (2026-10-29, macOS 27.2) | | Warmest | Not published as a kelvin figure (2026-10-28) | 500K | | Readable red | Not described (2026-10-28) | Yes, below 1500K | | Brightness | Software brightness control (2026-10-28, re-check) | Below the lowest brightness step, 5% floor by default | | Presets | Many | Six built in (Daylight 6500K, Focus 5000K, Evening 3400K, Candle 1900K, Ember 1200K, Midnight 500K), plus your own | | Licence | Online activation (2026-10-28) | Offline signed key | | Last Mac update | None since 2022, per Sundown (2026-10-28) | 1.0, 2026-10-29 | ## Where Iris leads Preset depth. Iris has more modes and presets than any other app on our comparison, and it runs on Windows. If you want to tune a dozen situations by hand, it has the knobs. ## Two things we could not confirm Iris's pricing page had moved when we checked on 2026-10-28, and Sundown's comparison posts disagree on the figure ($14.99 once on one, a subscription on another). Sundown's posts also say the Mac build has had no update since 2022. We have not verified either on Iris's own site, so both rows say re-check. Trustpilot carries complaints about Iris licensing; we link to the source rather than restate a score we have not counted. ## Where Atapa differs One question, "When do you usually go to bed?", sets the evening: warming starts 30 minutes before sunset, the deepest stop comes an hour before bed, and daylight is back by wake-up. Three intensities, Gentle, Warm and Deep red, end the night at 1900K, 1200K and 500K. Readable red keeps links and icons visible at the bottom of that range. The licence is an offline signed key; the app has no network code. It was tested on a 14-inch M5 Pro, macOS 27.2, on 2026-10-29, where apps that tint through a gamma table change nothing. Iris's site does not say whether it is one of them, and we have not installed it there. The check takes a minute and is on [the M5 page](/m5/). ![Atapa's Presets settings pane with the six built-in presets from Daylight at 6500K to Midnight at 500K, each with a warmth and brightness value.](/renders/settings-presets-light.webp) ## Price Iris is about $2 a month or $10 to $15 for a licence, to be re-checked on its current page. Atapa is $12 once for all of your own Macs, with a 14-day trial that asks for no card and a 14-day refund. After the trial Atapa keeps working; from day 29 without a key, warmth stops at 2700K and everything else continues. ## Choose Iris if You want preset depth, you are on Windows as well as Mac, and online licence activation is fine with you. Check its current pricing page first, because ours had moved. ## Choose Atapa if You want one evening curve instead of a dozen modes, deep red at 500K that stays readable, an offline licence, and an app with a dated changelog that was tested on an M5 Pro. [The comparison table](/compare/) has the whole field. ### Questions **Is Iris still maintained for Mac?** Sundown's comparison posts say Iris has had no Mac update since 2022, read 2026-10-28. We have not verified a release date on Iris's own site, and its pricing page had moved when we checked, so re-check before buying. Atapa's changelog is dated and public, and the M5 page carries a dated retest line after each macOS update. **What does Iris cost?** About $2 a month or $10 to $15 licences, read 2026-10-28; Sundown's posts disagree on the figure and Iris's pricing page had moved, so check the current page. Atapa is $12 once for all of your own Macs, with a 14-day trial that asks for no card and a 14-day refund, and no subscription. **Does Iris work on M5 Pro?** Iris's site does not state it, as of 2026-10-28, and we have not installed it on our M5 Pro. On M5 Pro and M5 Max, apps that tint through a gamma table report success and change nothing (Apple bug FB22273730). Atapa was tested on a 14-inch M5 Pro with macOS 27.2 on 2026-10-29 and changed the screen down to 500K. **Which one is private?** Iris activates its licence online, per its site on 2026-10-28. Atapa has no network code at all: the licence key is an offline signed string checked on the Mac, and there is no account, no update check and no analytics. Reviews on Trustpilot mention Iris licensing complaints; we link rather than restate a score we have not counted. **How warm do they go?** Iris does not publish a single kelvin figure; it offers many presets and modes. Atapa goes from 6500K to 500K, with Readable red below 1500K so links stay visible, and three intensities that end the night at 1900K, 1200K and 500K. ### Sources - Iris (iristech.co): https://iristech.co (read 2026-10-28) - Sundown blog (Iris price and last-update notes in its comparison posts): https://trysundown.com/blog (read 2026-10-28) - Apple Developer Forums, thread 819331 (FB22273730): https://developer.apple.com/forums/thread/819331 (read 2026-10-29) - Trustpilot reviews of iristech.co (licensing complaints, not re-counted by us): https://www.trustpilot.com/review/iristech.co (read 2026-10-27) ## Atapa vs Night Shift: is the built-in warmth enough? URL: https://atapa.app/vs/night-shift/ Updated: 2026-10-29 Choose Night Shift if a mild warm tint is enough. It is built in, and it still changes the screen on M5 Macs. Choose Atapa if Night Shift's warmest step is still too blue in a dark room. Apple does not publish a kelvin number for Night Shift. Night Shift is the one warmth tool every Mac already has. It works, it is free, and it is the right answer for many people. This page is for the evening when it is not warm enough. ## Side by side | Criterion | Night Shift | Atapa | |---|---|---| | Price | Built into macOS | $12 once, all of your own Macs; 14-day trial, 14-day refund | | M5 Pro built-in display | Works. Mild orange at More Warm, never red (2026-10-29, macOS 27.2) | Works, 6500K to 500K (2026-10-29, macOS 27.2) | | Warmest | Apple publishes no value; independent measurements around 2700 to 3000K (2026-10-28) | 500K | | Red at all | No red setting | Readable red below 1500K: blue and green folded into red | | Dims below the lowest brightness step | No | Yes, 5% floor by default | | Schedule | Sunset to sunrise or custom times | One bedtime question: warming 30 min before sunset, deepest 1 h before bed, back by wake-up | | Automation | Control Center toggle, schedule | Shortcuts actions, Focus filter, URL scheme, CLI | | Network use | Part of macOS | None | ## Where Night Shift leads Zero install. It is in System Settings, Displays, and in Control Center. It has a sunset-to-sunrise schedule. It still changes the screen on the M5 Pro and M5 Max, which f.lux and other gamma-table apps do not; on our 14-inch M5 Pro on 29 October 2026 it turned the panel mildly orange at More Warm. If that tint is enough for you, you are done, and there is nothing to buy. ![macOS Night Shift settings on our M5 Pro on 2026-10-29: "Turn on until tomorrow" on and the Color temperature slider at More Warm.](/evidence/nightshift-m5pro-2026-10-29.webp) ## Where it stops Apple does not publish how warm Night Shift goes. Independent measurements put More Warm around 2700 to 3000K. That is the color of a tungsten bulb: warm, and still with a lot of blue and green in it. In a dark room at 23:00 it is noticeably bright. Night Shift has no red setting and no way to dim below the hardware minimum. Atapa continues where Night Shift ends. Its three intensities end the night at 1900K (Gentle), 1200K (Warm) and 500K (Deep red). At 2700K, Atapa's own estimate is about 80% less melanopic light than an untouched screen; at 500K with Readable red the estimate is about 100%, because the green and blue outputs are zero. The method is on [the science page](/science/). ![Atapa's popover at 2700K: a warm white header, the warmth slider near the top of the evening range and the three intensity stops.](/renders/popover-2700K-light.webp) ## Red you can still read A plain red filter switches blue and green off, so blue links and icons turn black. Atapa's Readable red folds those channels into red below 1500K, so at 500K the words and the links are still there. Night Shift never reaches that range, so there is nothing to compare at 500K; the comparison is between a mild orange and a readable deep red. ## Dimming below the minimum The brightness keys stop at the lowest backlight step the hardware allows. On a MacBook Pro at night that step is still bright. Atapa adds a dim stage below it, down to a floor of 5% by default (Settings, Comfort, Dim floor, adjustable from 1% to 30%), and the brightness keys can keep driving it once you grant Accessibility. Night Shift does not dim. ## Price Night Shift is free. Atapa is $12 once for all of your own Macs, with a 14-day trial without a card and a 14-day refund. After the trial Atapa never stops working: from day 29 without a key, warmth stops at 2700K, about Night Shift's warmest, and dimming, the evening curve and Shortcuts keep working. ## Choose Night Shift if A mild warm tint at sunset is what you want, and you do not read in a dark room late. It is built in, it works on every Mac including the M5 Pro, and there is nothing to install or pay for. ## Choose Atapa if Night Shift's warmest step is still too blue in a dark room, you want deep red that stays readable, or you want the screen darker than the brightness keys allow. The step-by-step version is in [the guide for when Night Shift is not warm enough](/guides/night-shift-not-warm-enough/). ### Questions **Does Night Shift work on M5 Pro and M5 Max?** Yes. Night Shift uses a different path from the gamma table that the M5 bug ignores. On our 14-inch M5 Pro, macOS 27.2, on 2026-10-29, Night Shift at More Warm turned the panel mildly orange. It is the control to use when you want to confirm the gamma bug: if Night Shift moves the color and f.lux does not, you are in the bug. **How warm does Night Shift go?** Apple does not publish a kelvin value for Night Shift. Independent measurements put the warmest setting, More Warm, around 2700 to 3000K. On our M5 Pro on 2026-10-29 it was a mild orange and never red. Atapa's range goes on to 500K; its Gentle, Warm and Deep red intensities end the night at 1900K, 1200K and 500K. **Can I use Night Shift and Atapa together?** You can leave Night Shift on. Atapa does not switch it off, and its Settings show a tip when both are on. The simplest setup is to let Atapa run the evening and keep Night Shift as it was, because Atapa's curve already starts 30 minutes before sunset and reaches its deepest stop an hour before your bedtime. Either way, nothing breaks. **Does Night Shift dim the screen?** No. Night Shift changes color only, and the brightness keys stop at the hardware minimum. Atapa dims below that step, down to a floor of 5% by default, which you can raise in Settings, Comfort. Night Shift has a schedule and a Control Center toggle; Atapa has Shortcuts actions, a Focus filter, a URL scheme and a CLI. **Is Atapa free like Night Shift?** No. Night Shift is part of macOS. Atapa is $12 once for all of your own Macs, with a 14-day trial that asks for no card and a 14-day refund. After the trial it keeps working; from day 29 without a key, warmth stops at 2700K, about Night Shift's warmest, and the rest keeps working. Deep red needs a key. ### Sources - Apple Support: Use Night Shift on your Mac: https://support.apple.com/en-us/ht207513 (read 2026-10-28) - CircadianShield, Night Shift comparison (independent measurement of the warmest setting): https://circadianshield.com/vs/night-shift (read 2026-10-28) - Apple Developer Forums, thread 819331 (FB22273730): https://developer.apple.com/forums/thread/819331 (read 2026-10-29) ## Atapa vs Solace: a warmth app, or dark mode, wallpapers and warmth in one? URL: https://atapa.app/vs/solace/ Updated: 2026-10-29 Choose Solace if you want dark mode switching, wallpapers and screen warmth in one $4.99 app, read on 28 October 2026. Choose Atapa if you want deep red at 500K that stays readable, dimming below the lowest brightness step, or an app tested on an M5 Pro. Solace publishes no kelvin figure and does not state M5 support. Solace is a small, calm Mac app from Theodore HQ that does three things: dark mode on a schedule, wallpapers, and screen warmth. Atapa does one thing, warmth and dimming, and goes further with it. Which one you want depends on which of those you use every evening. ## Side by side | Criterion | Solace | Atapa | |---|---|---| | Price | $4.99 once (2026-10-28) | $12 once, all of your own Macs; 14-day trial without a card; 14-day refund | | Requirements | macOS 13 or later (2026-10-28) | macOS 14 or later, Apple silicon; Intel not supported in 1.0 | | Dark mode switching, wallpapers | Yes | No | | M5 Pro | Not stated on its site (2026-10-28); not tested by us | Works, 6500K to 500K on our M5 Pro (2026-10-29, macOS 27.2) | | Warmest | Not published (2026-10-28) | 500K | | Readable red | Not described (2026-10-28) | Yes, below 1500K | | Dims below the lowest brightness step | Not described (2026-10-28) | Yes, 5% floor by default | | Automation | Not listed (2026-10-28) | Shortcuts, Focus filter, URL scheme, CLI | | Network use | Not stated (2026-10-28) | No network code | ## Where Solace leads The bundle. If you switch between light and dark mode in the evening and like a wallpaper that follows, Solace does that and adds warmth for $4.99. It also runs on macOS 13, which Atapa does not. Theodore HQ writes in a calm voice, publishes honest comparison tables, and we have learned from that. ## Where it stops Solace publishes no kelvin figure for its warmth, so we cannot say how far it goes. It does not describe a red mode or a way to dim below the hardware minimum. Its site does not state whether it changes the screen on an M5 Pro or M5 Max, where apps that tint through a gamma table report success and change nothing (Apple bug FB22273730, open on macOS 27.2 as of 26 October 2026). We have not installed it on our M5 Pro, so we do not say either way. The one-minute check for that bug is on [the M5 page](/m5/). ## What Atapa adds Deep red to 500K, with Readable red from 1500K down so links and icons stay visible. Dimming below the lowest brightness step, with a 5% floor you can raise. One bedtime question that sets the whole evening: warming 30 minutes before sunset, deepest an hour before bed, back to daylight by wake-up. Nine Shortcuts actions, a Focus filter, a URL scheme and a CLI. And no network code at all. ![Atapa's popover holding 500K at 70% brightness, with the warmth slider at the bottom of its range and Gentle, Warm and Deep red as the three intensity stops.](/renders/popover-500K-light.webp) ## Price Solace is $4.99 once. Atapa is $12 once for all of your own Macs, with a 14-day trial that asks for no card and a 14-day refund. After the trial Atapa keeps working; from day 29 without a key, warmth stops at 2700K and everything else continues. ## Choose Solace if Dark mode switching and wallpapers are the features you use, warmth is a bonus, and $4.99 is the budget. On macOS 13 it is also the only one of the two that installs. ## Choose Atapa if Warmth is the point: you want deep red that stays readable, the screen darker than the keys allow, Shortcuts and a Focus filter, or an app tested on an M5 Pro. [The comparison table](/compare/) has the rest of the field. ### Questions **What does Solace do that Atapa does not?** Solace switches macOS dark mode, changes wallpapers, and adds screen warmth, in one app for $4.99 once, read 2026-10-28. Atapa does none of the dark mode or wallpaper work. If those are the features you use every day, Solace is the better fit and this page will not argue otherwise. **Does Solace work on M5 Pro and M5 Max?** Its site does not state it, as of 2026-10-28, and we have not installed it on our M5 Pro, so we do not say either way. On M5 Pro and M5 Max, apps that tint through a gamma table report success and change nothing (Apple bug FB22273730). The one-minute check is on the M5 page. Atapa was tested on a 14-inch M5 Pro, macOS 27.2, on 2026-10-29. **How warm does Solace go?** Solace does not publish a kelvin figure, as of 2026-10-28. Atapa goes from 6500K to 500K, and below 1500K it folds blue and green into red so links and icons stay visible. Atapa's three intensities end the night at 1900K, 1200K and 500K. **What do they cost?** Solace is $4.99 once and requires macOS 13 or later, read 2026-10-28. Atapa is $12 once for all of your own Macs, requires macOS 14 or later on Apple silicon, and has a 14-day trial that asks for no card and a 14-day refund. Both are paid once, with no subscription. **Which one is private?** Solace's site does not state its network use, as of 2026-10-28. Atapa has no network code at all: no account, no update check, no analytics, and the licence key is checked on the Mac with an offline signature. ### Sources - Solace by Theodore HQ: price, requirements, features: https://theodorehq.com/solace (read 2026-10-28) - Apple Developer Forums, thread 819331 (FB22273730): https://developer.apple.com/forums/thread/819331 (read 2026-10-29) ## Atapa vs Sundown: which one warms an M5 Pro? URL: https://atapa.app/vs/sundown/ Updated: 2026-10-29 Choose Sundown if you want their guide library, their Windows build, or their anti-dithering implementation and you are not on an M5 Pro or M5 Max panel. Choose Atapa if you need a tint that does not use the gamma table, readable deep red, and a single $12 purchase. On our M5 Pro (macOS 27.2, 29 October 2026), Sundown's own app said "Warming isn't available on this Mac yet." Sundown is the most complete screen-warmth app for Mac on features, and it has published more about this category than anyone else. This page is about one chip, one price model, and one readability trick, with the date on every fact. ## Side by side | Criterion | Sundown 1.6.4 | Atapa 1.0 | |---|---|---| | Price | $79 lifetime, $39 a year or $4.99 a month; 7-day trial that asks for a card (checkout seen 2026-10-29) | $12 once, all of your own Macs; 14-day trial without a card; 14-day refund | | Platforms | macOS 12 or later, Intel and Apple silicon; Windows in progress (2026-10-28) | macOS 14 or later, Apple silicon; Intel not supported in 1.0 | | M5 Pro built-in display | Not available. Its own app: "Warming isn't available on this Mac yet." (2026-10-29, macOS 27.2) | Works, 6500K to 500K (2026-10-29, macOS 27.2) | | Warmest | 500K claimed (2026-10-28) | 500K | | Readable red | Not described (2026-10-28) | Yes, below 1500K | | Dimming | Flicker-free mode dims through the gamma table, per its blog (2026-10-28) | Below the lowest brightness step, not through the gamma table | | Anti-dithering | Yes, "reduce dithering" | Yes, opt-in, for connected displays | | Automation | Not listed (2026-10-28) | Shortcuts, Focus filter, URL scheme, CLI | | Network use | "Zero telemetry" per its site (2026-10-28) | No network code | | Extras | Guide library, key pop-up styles, Sound Studio, panel backgrounds, ambient dimming, room adaptation, Explore, Invite a Friend | Eye rest breaks, evening ring estimate | ## Where Sundown leads Its guide library is large and well written, and it is what assistants quote about this category today. The app has far more customization than Atapa: styles for the brightness and volume pop-ups, a Sound Studio, panel backgrounds, ambient-light dimming and room adaptation from the light sensor, and an option to keep Night Shift off. It runs on Intel Macs, which Atapa 1.0 does not. A Windows build is in progress, per its site. If you are on an M1 through M4 Mac and want all of that, Sundown is a reasonable choice. ## What its own app says on an M5 Pro On our 14-inch M5 Pro, macOS 27.2, on 29 October 2026, Sundown 1.6.4 showed this notice at the top of its window: > "Warming isn't available on this Mac yet. Your Mac's display ignores the usual way apps warm the screen, so for now Sundown leaves your screen's color, brightness, Night Shift and True Tone as they are. We're working on it." ![Sundown 1.6.4 on our M5 Pro on 2026-10-29: the notice "Warming isn't available on this Mac yet" above a Warmth slider at 2000K and a Brightness slider at 100%.](/evidence/sundown-m5pro-2026-10-29.webp) The usual way is the gamma table, which macOS accepts and never applies on M5 Pro and M5 Max (Apple bug FB22273730, open on macOS 27.2). Sundown's blog describes its flicker-free mode as dimming through the same table. They say they are working on it, and we recheck after each Sundown update. Atapa tints in the display pipeline instead, and reached 500K on the same Mac the same day. ## Readable red Both apps state 500K as their warmest. The difference is what the screen looks like there. A plain red filter switches blue and green off, so blue links, icons and syntax highlighting go black. Atapa's Readable red folds those channels into red from 1500K down, so at 500K a blue link is still a visible darker red. Sundown does not describe a comparable mode on its site as of 2026-10-28. The numbers and simulated frames are on [the Readable red page](/readable-red/). ## Price and trial Sundown's checkout in 1.6.4 on 2026-10-29 listed $79 lifetime, $39 a year or $4.99 a month. The 7-day trial asked for a card ("$39/year after your 7-day trial"). Its blog posts list other prices on different pages, so check the checkout you are shown. Atapa is $12 once for all of your own Macs, with free updates for version 1. The 14-day trial asks for no card, and the refund window is 14 days. After the trial Atapa keeps working; from day 29 without a key, warmth stops at 2700K and everything else continues. ## Choose Sundown if You want its guides, its customization, or its Windows build later, and you are on an Intel or M1 to M4 Mac. On those machines its warming is not blocked by the M5 bug, and its extras are real. ## Choose Atapa if You are on an M5 Pro or M5 Max and need a tint that does not go through the gamma table, you want deep red that stays readable, or you want one $12 purchase with no card for the trial and no network code. Start with [the M5 page](/m5/) to see the test. ### Questions **Does Sundown work on M5 Pro and M5 Max?** On our 14-inch M5 Pro, macOS 27.2, on 2026-10-29, Sundown 1.6.4 showed: "Warming isn't available on this Mac yet. Your Mac's display ignores the usual way apps warm the screen, so for now Sundown leaves your screen's color, brightness, Night Shift and True Tone as they are. We're working on it." We have not tested it on an M5 Max. We recheck after each Sundown update and date the result. **What does Sundown cost compared with Atapa?** Sundown's checkout in version 1.6.4 on 2026-10-29 listed $79 lifetime, $39 a year or $4.99 a month, with a 7-day trial that asked for a card ("$39/year after your 7-day trial"). Its own blog posts list other prices, so check the current checkout. Atapa is $12 once for all of your own Macs, with a 14-day trial that asks for no card and a 14-day refund. **Which one goes warmer?** Both state 500K. Sundown's figure is its own claim, and on our M5 Pro on 2026-10-29 its warming was not available, so we could not see it. Atapa reached 500K on the same Mac the same day. Atapa's Readable red folds blue and green into red below 1500K so links stay visible; Sundown does not describe a comparable mode on its site as of 2026-10-28. **Does Sundown's flicker-free mode work on M5?** Sundown's blog describes its flicker-free mode as dimming through the gamma table. On M5 Pro and M5 Max, macOS accepts gamma tables and never applies them (Apple bug FB22273730), which is the same reason the warming is unavailable there. Atapa's dimming does not use the gamma table. No software, Atapa included, removes the PWM flicker of the panel's own backlight. **Which one is private?** Sundown's site says zero telemetry. Atapa has no network code at all: no account, no update check, no analytics, and the licence key is checked on the Mac with an offline signature. Sundown's app includes an Explore section with partner products and an Invite a Friend feature; Atapa has neither. ### Sources - Sundown (trysundown.com), app version 1.6.4 trial on our M5 Pro: https://trysundown.com (read 2026-10-29) - Sundown blog (flicker-free mode description, comparison posts): https://trysundown.com/blog (read 2026-10-28) - Apple Developer Forums, thread 819331 (FB22273730): https://developer.apple.com/forums/thread/819331 (read 2026-10-29) ## Contact Kevin Hofmann, Soulrise LLC. hello@atapa.app.