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Screens and sleep: how long before bed should kids turn off devices?

Artovia Labs · · 7 min read

Can a phone sitting next to the bed affect a child's sleep, even if it's never switched on? A review covering more than 125,000 children gives a surprising answer: yes. Children who had a device nearby at night slept too little more often, even when they didn't use it [2].

To understand how that's possible, let's look first at how sleep begins, and then at why children are different from adults. At the end, we'll work out together what time screens should go off for your child.

How does sleep begin?

As evening darkens, the brain starts releasing a hormone called melatonin. Melatonin tells the body "it's night" and gets it ready for sleep. The thing that disrupts that signal most is light reaching our eyes.

A study in Japan measured how differently light affects children and adults [3]. Researchers measured melatonin in 13 children and 13 adults in the evening under two kinds of light: dim light, and 580 lux, about as bright as a well-lit room. The bright light suppressed melatonin by about 46% in adults and about 88% in children. Almost double.

The second experiment was even more striking. Ordinary home lighting (about 140 lux) didn't significantly affect adults' melatonin, but it did suppress children's [3]. The researchers point to children's larger pupils and clearer lenses: more light gets into the eye. The study was small, but it shows why evening light matters especially for kids.

So is light the only problem with screens? If it were, dimming the screen or turning on night mode would be enough.

It isn't just the light

According to a review of how screens affect sleep, there are at least three pathways [4]:

Night mode or a blue-light filter only touches the third. It doesn't change the time an extra hour of gaming takes from sleep, or the excitement it creates.

And what about a phone that just sits in the room? No one knows for sure yet. The review that combined 20 studies found that children who had a device nearby at night but didn't use it were also more likely to get too little sleep, but it didn't measure why [2]. Still, the finding supports a simple rule: devices spend the night outside the bedroom.

To put that rule into practice, you first need to know one thing: how much sleep your child needs.

How much sleep does my child need?

The American Academy of Sleep Medicine recommends [6]:

AgeRecommended sleep per day
3–5 years10–13 hours (including naps)
6–12 years9–12 hours
13–18 years8–10 hours

Now for the calculation we promised. A 9-year-old who wakes at 7 a.m. and needs at least 9 hours of sleep should be asleep by 10 p.m. If the hour before bed is screen-free, screens should go off by 9 p.m. at the latest. For a child who wakes earlier or needs more sleep, move that time earlier.

Working out the time is half the job. The other half is keeping it every night.

Why does the same time every night matter?

A study of 10,085 mothers of children aged 0 to 5 in 13 countries looked at how bedtime routines relate to sleep [7]. A routine means the same steps in the same order every evening: a bath, brushing teeth, a book.

The more nights a week children had a routine, the better they slept [7]. Children with a routine every night went to bed earlier, fell asleep faster, woke less at night and slept longer overall. The difference showed up in the daytime too: among preschoolers, daytime behavior problems were reported for 22.9% of those who never had a routine, compared with 9.1% of those who had one every night [7].

This was a survey. It relies on what mothers reported, and it shows a link, not a cause; it was also funded by a baby-care products company. For school-age children, the American Academy of Sleep Medicine makes a similar point: getting the recommended amount of sleep on a regular basis is linked to better attention, behavior and learning [6].

Screens are the part of the routine that slips most easily: "one more episode" can push bedtime later every night. Fixing the time screens go off makes room for the rest of the routine.

4 rules you can use at home

  1. Screens off an hour before bed. That's the AAP's recommendation [5]. Fix the time so it isn't renegotiated every evening.
  2. Devices sleep outside the bedroom. Pick a shared charging spot, like the kitchen or living room. The AAP recommends screen-free bedrooms [5], and research links even having a device in the room to too little sleep [2].
  3. Plan the freed-up hour. Decide in advance what fills the time screens leave: a bath, a book, packing tomorrow's school bag. These can be your child's evening tasks; we look at which skills chores go along with in children in our guide to screen time by age.
  4. Make the rule apply to everyone. Parents' phones can spend the night at the charging spot too. The AAP encourages parents to model healthy screen use [5].

Questions parents often ask

Does night mode help at all?

It reduces the screen's light, and that's a good thing. But light is only one of the three ways screens affect sleep [4]. The time and the excitement stay the same. So night mode doesn't replace a screen-free last hour.

My child uses their phone as an alarm. What should we do?

A simple alarm clock solves this. Then there's no reason for the phone to spend the night in the room.

The bottom line

Screens affect sleep in three ways: by stealing time, by keeping the mind alert, and through light. Children are more sensitive to that light than adults. The two most effective rules are also the simplest: screens off an hour before bed, and devices out of the bedroom at night.

Sleep is at the top of the list of things screens shouldn't replace. You'll find the rest, along with recommended screen time by age, in our guide to screen time by age.

Sources

  1. Hale L., Guan S. (2015). Screen time and sleep among school-aged children and adolescents: a systematic literature review. Sleep Medicine Reviews, 21, 50–58. PubMed
  2. Carter B. et al. (2016). Association Between Portable Screen-Based Media Device Access or Use and Sleep Outcomes: A Systematic Review and Meta-analysis. JAMA Pediatrics, 170(12), 1202–1208. doi:10.1001/jamapediatrics.2016.2341
  3. Higuchi S. et al. (2014). Influence of light at night on melatonin suppression in children. Journal of Clinical Endocrinology & Metabolism. PubMed
  4. Cain N., Gradisar M. (2010). Electronic media use and sleep in school-aged children and adolescents: A review. Sleep Medicine, 11(8), 735–742. PubMed
  5. AAP Council on Communications and Media (2016). Media and Young Minds. Pediatrics, 138(5), e20162591. doi:10.1542/peds.2016-2591
  6. Paruthi S. et al. (2016). Recommended Amount of Sleep for Pediatric Populations. Journal of Clinical Sleep Medicine, 12(6), 785–786. PMC4877308
  7. Mindell J. A., Li A. M., Sadeh A., Kwon R., Goh D. Y. T. (2015). Bedtime routines for young children: a dose-dependent association with sleep outcomes. Sleep, 38(5), 717–722. PMC4402657

This article is for general information and isn't medical advice. If you're concerned about your child's health, talk to your pediatrician. Written by Artovia Labs, the maker of Minu, based on the published sources listed above.