Screen Time Before Bed: A Mac Evening Routine by Kelvin
By Nikki NeislerCo-founder, Sundown
Screen time before bed can push sleep later, and the clearest evidence is about bright, blue-rich light in the last hours of the evening. In a controlled study at Brigham and Women's Hospital, people who read on a light-emitting eReader before bed took longer to fall asleep, felt less sleepy in the evening, secreted less melatonin and were less alert the next morning than when they read a printed book. On a Mac, though, most of the light side of that problem is something you can adjust, one setting at a time, in the two hours before you sleep.
This guide turns screen time before bed into a routine: what to change at two hours out, at one hour out, and at lights-out, with a screen warmth for each step. No study tested this ladder, so treat it as a practical plan that follows where the evidence points, which is toward less short-wavelength light, a dimmer screen and an earlier start. The biology of why blue light matters at night is covered in what your Mac display does to your sleep, and this page sticks to what to do.
What does screen time before bed actually do?
Evening screen time does two separate things, and only one of them is about colour. The first is light: a bright, cool-white screen close to your face tells your internal clock it is still daytime, which can delay melatonin and push sleep later. The second is arousal: an email, a game or a feed keeps your mind switched on regardless of what colour the pixels are.
The light half is well studied. Anne-Marie Chang, Charles Czeisler and colleagues published the eReader comparison in PNAS in 2015 (Chang 2015, PMID 25535358). The same people went to bed at the same time, and the only thing that changed was whether they read on a light-emitting device or a paper book, and on the device their circadian clocks ran later and their melatonin was suppressed. Four years earlier, Joshua Gooley and a Harvard team reported in the Journal of Clinical Endocrinology and Metabolism that ordinary room light in the hours before bed, compared with dim light, delayed the evening rise of melatonin and shortened how long it was produced (Gooley 2011, PMID 21193540). Gooley's exposure was room light rather than a screen, which is a reminder that your overhead lights count too.
The arousal half is the part no display setting can touch, and that limit belongs at the top of any guide like this one. A warm screen showing a stressful inbox is still a stressful inbox. Warmth deals with the light, so the routine below treats what you are looking at as a separate step.
Screen time before bed is also normal. In a November 2021 survey for the National Sleep Foundation's 2022 Sleep in America Poll, 58% of US adults said they often looked at screens in the hour before bed or in bed. If that describes you, you are in the majority, and the more useful question is what the screen is doing during that hour.
The evening routine, step by step
Everything below uses one scale, the colour temperature of the screen. Lower numbers mean warmer, redder light with less of the short-wavelength blue that the clock responds to most. Your Mac's default white is ordinary daytime white, the same reference white as average daylight. Sundown's menu bar slider runs from ordinary daytime white down to a deep red, in small steps, so each setting below is a position you can actually find. If colour temperature is new to you, colour temperature explained walks through what the numbers mean. These settings describe how the screen looks, and they make no promise about how you will sleep. No study has tested Sundown itself.
Two hours before bed: a warm white and lower brightness
Set the display to a warm white and bring the brightness down as far as you can while still reading comfortably. At this setting a white page looks like paper under a bedside lamp: whites turn gold, blues go muddy, and text stays perfectly readable, so this is the setting for real work you still have to finish. It is also roughly where Night Shift stops.
Then look up. Gooley's result was about room light, so dim the overhead lights and switch to lamps if you can. A warm screen in a brightly lit kitchen is only half the change.
One hour before bed: candle flame, then deep orange
Drop to the orange of a candle flame. Photos lose their colour accuracy here, which is fine because you should not be editing photos at this hour. If you are still on the screen after half an hour, go further, to where the display turns a deep orange and blues mostly disappear.
This is also the content step. Stop starting new work. Finishing a reply is fine; opening a new project is how an hour becomes three. Reading, a slow video or a list for tomorrow all suit a deep orange screen better than a spreadsheet does.
Lights-out: deep red, or close the lid
If you are still using the Mac at lights-out, set it to a deep red. At that setting there is no lamp to compare it to; the screen shows a deep red, the white of a page becomes dark red, and colours are gone. It is readable, and it is the setting to use for the last message or the alarm check. Our guide to a red screen filter for sleep covers when a fully red screen is worth it.
The better option is to close the lid, because no setting on any screen beats not looking at one.
The routine at a glance
| When | Setting | What the screen looks like | Other change |
|---|---|---|---|
| Daytime | Ordinary daytime white | Standard daylight white | Full brightness is fine |
| 2 hours before bed | Warm white, lower brightness | Paper under a bedside lamp | Dim overhead lights |
| 1 hour before bed | Candle flame, then deep orange | Candlelight orange, then deep orange | Stop starting new work |
| Lights-out | Deep red | Deep red, no colour | Better still, close the lid |
Sundown has a custom schedule if you want the steps to follow a set time, but you can do this whole routine by hand from the menu bar in a few seconds a night, and starting by hand is a good way to find the settings you actually like.
What does the research on blocking evening blue light show?
The strongest direct evidence comes from glasses rather than screens, and it is worth keeping that in mind. The study most often quoted is Ostrin, Abbott and Queener at the University of Houston College of Optometry (PMID 28656675). Ostrin et al. (2017) found blue-blocking lenses raised nocturnal melatonin ~58% in healthy adults, who also slept ~24 minutes longer. That result came from two weeks of wearing short-wavelength-blocking amber glasses in the evening. It was a before-and-after design without a placebo group, and it tested lenses, not display software.
The reasoning that carries it to a Mac is simple: glasses and a warm screen both reduce the short-wavelength light reaching your eyes. We think that is a reasonable step to take, and the Sundown science page says plainly that it is an inference, not a finding. Every study above is listed there with what it did not test.
If you have insomnia symptoms
One trial looked specifically at people with insomnia. Ari Shechter and colleagues at Columbia University had fourteen adults with insomnia symptoms wear amber lenses or clear placebo lenses for the two hours before bed, for a week each, in a randomised crossover design (Shechter 2018, PMID 29101797). Scores on an insomnia rating scale improved with the amber lenses, as did reported sleep time and sleep quality. Most of those measures were self-reported, the group was small, and again it was a lens study.
So a warm, dim evening screen is a sensible and cheap thing to try, but it is not a treatment. If you have had trouble sleeping most nights for weeks, talk to a doctor or a sleep clinician. The usual first recommendation for persistent insomnia is a structured programme called cognitive behavioural therapy for insomnia (CBT-I), and it works on the arousal and habit side that no screen setting can reach.
What helps less than people think
Night Shift left where it is. Night Shift takes the screen from ordinary daytime white to a warm white, which cuts the blue channel, but it leaves brightness alone and it is only the first step of this routine.
A warm screen at full brightness. Colour and brightness work together. Heo and colleagues at Samsung Medical Center had healthy adults play smartphone games in the evening on a normal phone and on one with blue light suppressed, in a double-blind crossover (Heo 2017, PMID 28017916). Some sleepiness and mood measures differed between the phones, but the difference in serum melatonin was not statistically significant. Reducing blue alone, on a bright screen, is not a guaranteed effect, and that is why this routine lowers brightness and room light alongside warmth.
Dark mode on its own. Dark mode lowers how much light the screen emits but leaves the white point where it was. We worked through the macOS system colours in does dark mode reduce blue light.
Questions people ask about screen time before bed
How long before bed should I stop using screens?
No study has set a cut-off for Mac use. The two-hour start in this routine is a practical choice, borrowed loosely from the insomnia trial above, which tested amber lenses worn for two hours before bed rather than a warmer display. If stopping completely is not realistic, warming and dimming the screen through the evening and closing the lid at lights-out means less light, and less blue-rich light, from the display.
Is a warm screen as good as no screen?
No. A deep red screen still gives off light, and the content on it still keeps your mind busy. A warm screen gives off less short-wavelength light than a cool one, and a closed lid gives off none.
Does dark mode help sleep?
Our dark mode calculation found that dark mode lowers the relative luminance of what a Mac shows, so the screen gives off less light overall. It does not change the colour temperature of the white that remains, and no trial has tested dark mode for sleep. For evening use, pair it with a warm setting and lower brightness.
If you want to change your screen time before bed starting tonight, Sundown puts the warmth slider in your menu bar, from ordinary daytime white down to a deep red. Start at a warm white two hours before bed and see how far down you like it. There is a 7-day free trial on monthly and annual plans: Start your 7-day free trial at trysundown.com.
