Keep Night Mode On All Day

Most phones and tablets have a "night mode" or "warm display" setting designed to reduce blue light in the evening. The idea is to help your body wind down before sleep. But if your toddler uses a screen at any time of day, there is a good reason to keep that filter on permanently.

Why toddlers are more affected by screen light

Young children are not just small adults. Their eyes are structurally different. Toddlers have larger pupils and more transparent lenses than grown-ups, which means more light (especially short-wavelength blue light) reaches the back of their eyes (LeBourgeois, 2017).

A 2018 study from the University of Colorado Boulder measured how preschool-age children's bodies respond to bright light in the hour before bedtime. The children's melatonin levels were reduced by around 88%, a much larger response than is typically seen in adults (Akacem, 2018). Melatonin is the hormone that signals to the body that it is time to sleep, and even daytime changes can affect mood and alertness.

What night mode actually does

Night mode (also called "Night Shift" on iPhone, "Night Light" on Android, or "Night light" on Windows) shifts the screen's colour temperature warmer. It reduces blue-wavelength output and replaces it with softer amber and orange tones. It also typically reduces overall brightness slightly.

It is worth being honest: the specific evidence on blue-light-filtering glasses and screen overlays is mixed. A randomised trial in adults found no significant improvement in sleep from blue-light-blocking lenses alone (Singh, 2023). But reducing overall screen brightness and shifting to warmer tones does appear to help, because the key variable is total light intensity reaching the eyes, not just the blue portion in isolation (Royal College of Paediatrics and Child Health, 2019).

The ten-second change

On any device your toddler uses, turn on the warm display filter and leave it on permanently, not just in the evening. Then lower the screen brightness to the most comfortable level. On most devices you can find these settings under Display or Screen.

This is not a magic fix. The most effective approach, supported by both the Royal College of Paediatrics and Child Health and the American Academy of Pediatrics, is to avoid screens entirely in the hour before bedtime (Royal College of Paediatrics and Child Health, 2019) (Council on Communications and Media, 2016). But for the screen time that does happen during the day, a warm, dim display is a simple, evidence-backed improvement.

How to turn it on

iPhone or iPad: Settings > Display & Brightness > Night Shift. Turn it on and set the schedule to "Sunrise to Sunset" so it stays on all day. Apple's guide.

Android (Pixel, stock Android): Settings > Display > Night Light. Google's guide.

Samsung Galaxy: Settings > Display > Eye comfort shield. Samsung's guide.

Amazon Fire tablet: Swipe down from the top and tap Blue Shade. Or go to Settings > Display > Blue Shade. Amazon's guide.

Mac: System Settings > Displays > Night Shift. Apple's guide.

Windows: Settings > System > Display > Night light. Microsoft's guide.

Chromebook: Settings > Device > Displays > Night Light. Google's guide.

One thing to try today

Pick up whatever device your child uses most. Go to display settings. Turn on the warm colour filter. Turn the brightness down. It takes ten seconds, and it means every minute of screen time from now on is a little gentler on developing eyes.