Why are children more sensitive to light at night?
Children have larger pupils and clearer lenses than adults, so more light reaches the back of the eye. In a study comparing primary school children with adults under the same moderately bright evening light, melatonin, the hormone that makes you sleepy, was suppressed by about 88% in children versus 46% in adults. Under ordinary room light at home, children’s melatonin was suppressed while adults’ wasn’t.1
Does puberty change it?
Sensitivity changes as kids grow. In one study, children in early and mid puberty were more sensitive to evening light than teens in late puberty.2 Teenagers have a different challenge: their body clocks naturally drift later, and evening light pushes them later still. See night owls and delayed sleep phase.
What about screens at bedtime?
In adults, reading on a light-emitting screen before bed lowered melatonin, delayed the body clock and left people less alert the next morning compared with reading a printed book.3 Since children respond more strongly to evening light, the same habits are likely to affect them at least as much.
Gentler evenings for kids
- Dim the house lights in the hour or two before bed.
- Use warm, low-blue light in bedrooms and living areas.
- End screen time well before lights out, and keep screens out of the bedroom overnight.
- When screens are used in the evening, keep them dim and warm.
- Get outside in daylight in the morning.