Night light and eye strain

Two controls, two effects

Night light shifts the colour balance towards amber by reducing the blue component. The screen looks warmer. It does not meaningfully reduce total light output.

Brightness reduces output across the board. In a dark room this is the change that removes the sensation of glare, and it is the one most people actually need at 11pm.

Use both if you like the warmer tone, but do not expect the colour shift to substitute for turning the level down.

Turning on night light

Windows 10 and 11 both provide it under Settings › System › Display › Night light. Open the settings to set strength and a schedule — either sunset to sunrise using your location, or fixed hours. A strength around the middle of the range is warm enough to notice without making whites look orange.

What the evidence supports

Blue-light filtering is often marketed as a fix for eye strain and for sleep. The picture is more modest than the marketing. Reviews of the available trials have generally not found strong evidence that blue-light filtering alone reduces eye strain, and the effect on sleep appears to depend more on total light exposure and screen time before bed than on colour temperature specifically.

What consistently does help is unglamorous: matching screen brightness to the room, increasing text size rather than leaning closer, and taking regular breaks that let the eye focus at distance — the widely taught habit of looking about twenty feet away for twenty seconds every twenty minutes. Dry eyes from reduced blink rate account for a large share of what people describe as strain.

Set the room, then the screen

A bright screen in a dark room is the worst combination, and it is the one most evening setups fall into. Adding a modest lamp behind or beside the monitor lets you run the screen at a lower level while still reading comfortably, which reduces the contrast between screen and surroundings that the eye keeps adapting to.

This is also where scheduling earns its place: a level that is right at midday is too bright by evening, and a tool that changes it automatically removes the need to remember. See the comparison for which methods support that.