Screens and light in the evening
What it's about
In children under five, more screen time is linked with poorer sleep in studies; the evidence is considered very weak (Janssen 2020). In preschool children it is well studied that bright light in the evening strongly suppresses the sleep hormone melatonin and shifts the body clock later (Hartstein 2022, Hartstein 2023). Whether the colour of the light matters much has only been studied preliminarily (Hartstein 2025).
What expert bodies recommend
The AAP recommends turning off all screens at least one hour before bedtime. The WHO recommends no screen time for children under two and at most one hour a day for two- to four-year-olds. Moon Hour has a night mode that turns dark and warm from 7 pm.
If you are worried
Experts recommend contacting your paediatrician or your local out-of-hours medical service if you are worried.
Sources
- Janssen et al. 2020: Screen time and sleep in children under 5 (review)
- Hartstein et al. 2022: Evening light and melatonin in preschool children
- Hartstein et al. 2023: Evening light shifts young children’s body clock
- Hartstein et al. 2025: Evening light colour in preschool children (preliminary)
- AAP (healthychildren.org): Healthy sleep habits
- WHO 2019: Guidelines on physical activity, sedentary behaviour and sleep for children under 5
General information, not a substitute for medical advice.
Sources checked: November 2026