How to enable Night Light in Chrome OS

Reduce exposure to blue light from your Chrome OS device screen at night by changing these settings.

Words "Chrome OS Night Light", centered on screen. Left half looks cool white, right half looks warm red.

Two photos of a Chromebook display, both with Night Light enabled. Left half set to a cooler temperature, right half set to a warmer temperature.

Image: TechRepublic/Andy Wolber

Tech professionals accustomed to local area networks (LANs), need to concern themselves with a new type of LAN: Light at night. Specifically, the light at night from phone, tablet, and laptop screens that negatively affects sleep.

A study at the University of Haifa in 2017 found that "exposure to blue light reduced the duration of sleep" in subjects, but also "that exposure to blue light drastically disrupts the continuity of sleep."

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If you use a Chrome OS device, or oversee the configuration and settings of other people's systems, you can adjust a few settings to minimize the impact of the light from these screens on people's sleep. Below are tips on how to reduce blue light exposure on Chrome OS devices; similar settings are also available on Android, iOS, macOS, and Windows systems.

Enable and configure Night Light

To enable Night Light in Chrome OS, open Settings, and look for the Displays section, where Night Light can be enabled. Adjust the slider to turn Night Light on, and then you'll also be able to adjust two other features: Color temperature of the display and the schedule (Figure A).

Figure A

Screenshot of Night Light setting enabled, with color temperature (cooler to warmer) and schedule options drop-down shown.

In the Chrome OS display settings, enable Night Light, and then adjust the display color temperature and schedule.

The Color Temperature setting represents a range of cooler colors, which include more more white and blue, to warmer colors, which tend toward red. In most cases, a slight shift of the slider to the right of center will adjust your display subtly toward a redder color, with less blue and white. Give yourself a few minutes in a dim or dark room to adjust to the new colors. Move the setting too far toward the Warmer setting, and it may seem like your screen had a red translucent film over it..

You can also adjust the schedule for this shift with the Never, Sunset To Sunrise, and Custom settings. The first option leaves it to you to manually turn Night Light on or off, which you can toggle with a tap or click when you pull up the settings in the lower right corner. Custom lets you choose times to turn Night Light on and off daily, which makes sense if you often go to sleep at a consistent time; for instance, set Night Light to turn on an hour or more before you head to sleep, and then have it turn it off before you get up (Figure B).

Figure B

Screenshot of settings, including Night Light, available on a Chrome device when you tap/click/select the menu in the lower right corner of a screen (where time, Wi-Fi, and notifications display)

You can configure Night Light to switch on automatically from Sunset to Sunrise, or if you prefer, manually adjust Night Light with a tap or click in the quick access settings (shown).

If you're trying to minimize blue light exposure that isn't in sync with daylight, select Sunset to Sunrise to automatically enable Night Light during night hours. For this setting to work, your device needs to be able to identify your location and/or time zone. Check to make sure the Time Zone is accurate in Settings | Advanced | Time Zone, then either let the system set your time zone automatically--via your IP address or Wi-Fi or mobile network connection--or by manually specifying your time zone (Figure C).

Figure C

Screenshot of Chrome OS time zone options: detect (from IP address or Wi-Fi/mobile network) or select time zone manually.

If you choose the Sunset to Sunrise schedule, make sure your time zone is configured correctly.

Reduce brightness

In addition to enabling Night Light, you may also want to reduce the brightness settings of your screen before sleep as well. While I'm not aware of a specific study of the impact of Chrome Night Light and brightness settings on sleep, a study by researchers in 2018 at the Lighting Research Center at Rensselaer Polytechnic Institute looked at the impact of similar settings and brightness adjustments on an iPad.

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"The study's main takeaway is that changing screen color alone is insufficient for limiting the impact of PEDs [portable electronic devices] on melatonin levels in the evening, and that screen brightness should also be reduced," said the report.

So when Night Light turns on, you also may want to reduce the brightness of your screen.

Your actions?

Of course, light from screens may be only a small portion of the light at night that people experience. Several organizations are experimenting with "Circadian Lighting," thanks to lights that can change color temperature.

Have you enabled settings on your systems to adjust color temperature and brightness at night? Have you taken additional steps to adjust the lighting in your home or office after sunset? If so, have you noticed an impact on your sleep, work, or health? Let me know in the comments or on Twitter (@awolber).

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