Your display emits blue light—the kind of light you see during the day—which can keep you up at night. To help you get to sleep, turn on the night light and your display will show warmer colors at night that are easier on your eyes. Night light isn't available if your device uses certain drivers (DisplayLink or Basic Display). To schedule night light so it turns on automatically:
Select Start > Settings > System > Display > Night light settings. If your night light toggle above the link is grayed out, you may need to update your display driver. See Update drivers in Windows 10.
Under Schedule, toggle Schedule night light to On. Then, either select Sunset to sunrise, or select Set hours and enter custom times for the night light to turn on and off.