Night Shift on Mac: how to set it up and what it does for sleep

Night Shift is a Mac setting that shifts your screen's colors toward the warm, yellow end after dark, so it gives off less blue light in the evening. You turn it on in System Settings > Displays > Night Shift, and the easiest schedule is Sunset to Sunrise, which follows the sun where you are.

It is worth turning on, because a warmer screen tends to feel easier on the eyes in a dim room. But the research on whether it helps you sleep is less convincing than the feature's reputation. How bright your screen is, and how late you keep using it, matter more than its color. This post covers both: how to set Night Shift up well, and what to do alongside it.

What Night Shift does

Apple describes Night Shift as shifting the colors of your display to the warmer end of the color spectrum after dark. Whites look more like candlelight than daylight, and blues lose some of their punch. The screen is not dimmer, though it can look a little softer because of the color.

A few things it does not do:

• It doesn't change brightness. That is a separate setting.
• It doesn't apply to televisions or projectors connected to your Mac. The Night Shift panel says so itself.
• It doesn't change the colors in your files or apps. It only changes how your display shows them.

How to turn it on and schedule it

In recent versions of macOS:

1. Choose Apple menu > System Settings, then click Displays in the sidebar.
2. Scroll to the bottom of the Displays page.
3. Click the Night Shift button.
4. Next to Schedule, choose Sunset to Sunrise or Custom.

Sunset to Sunrise is the one to pick if you are unsure. It moves with the seasons, so you never have to touch it again. To work, it needs location for the time zone to be on. If macOS warns you about this, turn on Location Services in System Settings > Privacy & Security, and check that setting the time zone is allowed in its list of system services.

Custom lets you set your own times, for example from 8 PM to 7 AM. That suits people whose evenings don't line up with sunset: in summer, sunset can come so late that the screen stays blue-white well into the evening.

Color temperature

The same panel has a Color Temperature slider, from Less Warm to More Warm. If you want Night Shift to make a clear difference to the color, move it toward More Warm and live with it for a few evenings before you decide. Apple notes that warmer settings may affect the look of some onscreen motion.

Turning it on now, or off for a while

To turn Night Shift on right away, use the Manual switch in the same panel, which turns it on until tomorrow (or until sunrise, depending on your schedule), or open Control Center, click Display and click Night Shift. Control Center is also the quick way to switch it off for an evening, which is worth doing if you are editing photos or checking colors at night: Night Shift will make everything look warmer than it really is.

What the research shows, and what it doesn't

The idea behind Night Shift comes from solid science. Light reaching the eyes in the evening, especially light rich in blue, holds back melatonin, a hormone that rises in the evening as part of the body's sleep rhythm, and it can push the body clock later. That is well established. Most of the strong evidence comes from studies of room lighting and bright light, though, which is far more light than a screen at arm's length gives off.

When researchers have tested screen night modes on real sleep, the results have been underwhelming. The small number of studies on night-mode filters have not found clear improvements in how quickly people fall asleep or how well they sleep. That doesn't mean Night Shift does nothing. It means its effect, if any, is probably modest, and smaller than other things you do in the evening.

Those other things are mainly two. First, the amount of light: a screen at full brightness in a dark room lights up your face, whatever color it is. Second, what is on the screen. A tense work email, one more episode or half an hour of scrolling keeps the mind switched on, and it uses up time you could have spent asleep. Many sleep researchers point to those as a bigger problem than the blue light itself. Screens before bed looks at that side of it in more detail.

And on eye health: the American Academy of Ophthalmology has said that blue light from screens is not known to damage the eyes, and it does not recommend blue-light-blocking glasses for screen use. Night Shift is about comfort and the body clock, not about protecting your eyes.

Why dimming and stopping earlier matter more

If you want your evenings at the Mac to be kinder to your sleep, these do more than color alone.

• Turn the brightness down. As the room gets darker, the screen should come down with it. If your Mac has Automatically adjust brightness in System Settings > Displays, keep it on. Setting your Mac's brightness for comfort goes into this in detail.
• Dim the room, but not to nothing. A lamp or two of warm, low light is better than a bright overhead light, and better than a dark room with one bright screen in it.
• Try Dark Mode at night. Light text on a dark background puts much less light in your eyes overall. Whether Dark Mode is better for your eyes covers when it helps and when it doesn't.
• Stop earlier. The most effective change is the simplest one. Pick a time to stop working, and leave the last hour before bed for something that isn't a screen.
• Keep your bedtime steady. A regular bedtime and some daylight in the morning probably do more for the body clock than any evening screen setting.

A simple evening routine for your screen

Put together, an evening at the Mac might look like this:

1. At sunset, Night Shift comes on by itself.
2. When you switch on the evening lights, turn the screen down a few steps.
3. If you like it, switch to Dark Mode for the evening.
4. An hour or so before bed, finish what you are doing and close the laptop.

The first step happens on its own once you set it up. The rest depends on you noticing the time, which is the hard part when you are absorbed in something.

A nudge from the notch

Notchpals can cover the step you are most likely to skip. The Eyes character in your crew has one evening moment, Dim the screen, which can come once between 9 PM and midnight to ask you to turn the brightness down or warm the colors. Blip, the Eyes character every copy of the app comes with, can hardly believe a screen changes color at all.

BlipWarm colors at night? Your screen can change color? I love this planet!

It only asks. Notchpals doesn't touch your display settings, so the dimming, and Night Shift itself, stay in your hands. Press Done once the screen is softer, or Later to hear about it once more, 20 minutes on. If you also have a Sleep character in your crew, the evening has two more visits. Wind down comes during the last hour before your bedtime (you set it in Notchpals), and Bedtime turns up only if your bedtime has passed and you are still at the Mac.

Night Shift is a good setting to turn on once and forget. Just don't expect it to do the work of a dimmer screen and an earlier night.