Children who sleep with the light on and get too little sleep are more likely to be nearsighted. In a British Journal of Ophthalmology study of 4,571 Chinese schoolchildren, published online 26 October 2026, 48% of kids with both habits had myopia, and first graders with both had about 3 times the odds.
Key takeaways
- A cross-sectional study in the British Journal of Ophthalmology (Beijing Tongren Eye Center, published online 26 October 2026) examined 2,630 first graders and 1,941 seventh graders in China.
- Students who slept with the lights on and also slept too little had the highest myopia rate in the study: 48.41%.
- In first graders, that combination was linked with about 3 times the odds of myopia; in seventh graders, about 1.8 times. The two habits together added up to more than either alone.
- It is an association from one snapshot in time, not proof of cause, and earlier night-light studies disagreed.
- The one change: make lights-out a fixed part of a child’s evening plan, with a bedtime that leaves room for the 9 to 12 hours of sleep that 6- to 12-year-olds need.
What did the 2026 study on night light and myopia find?
Sleeping with a light on and sleeping too little were each linked with myopia, and the pair together was linked with the most. The link was strongest in the youngest children.
The team, led by Shi-Ming Li and Ningli Wang at Beijing Tongren Hospital, used data from the Anyang Eye Study in Anyang, China. Questionnaires asked about sleep lighting, fluorescent light and sleep duration, and every child had a full eye exam with focusing-relaxing drops and a measurement of eye length.
| Group in the study | What was found |
|---|---|
| All students, lights on + short sleep | 48.41% had myopia, the highest rate of any group |
| First graders, lights on + short sleep | about 3 times the odds of myopia |
| Seventh graders, lights on + short sleep | about 1.8 times the odds of myopia |
| Girls, younger grades, children of nearsighted parents | the light-on link was stronger |
The two habits compounded: about 40% of the extra risk in children with both came from the combination itself.
Why would bedroom light or short sleep matter for a child’s eyes?
Nobody knows yet. The eye keeps time too: in people and in animals, the length of the eye rises and falls over the day, and the retina has its own clock. Whether modern light at night disturbs that rhythm enough to change how a child’s eye grows is not known.
The 2026 study was not designed to show why. For how evening light shifts sleep later, see Does Electric Light Make Us Sleep Later? A 12-Year Study.
Didn’t earlier studies say night lights were fine?
Yes, so this study is a nudge, not a verdict.
A 1999 Nature report by Graham Quinn and colleagues at the Children’s Hospital of Philadelphia found more myopia among children who had slept with a light on before age 2. In 2000, a US study of schoolchildren (Zadnik and the CLEERE Study Group, also in Nature) found no link between night-time nursery lighting and myopia. The 2026 study looked at light during sleep in school-age children rather than in infancy, and the light-on link was stronger in children of nearsighted parents.
What does help prevent myopia in children?
Time outdoors in daylight has the strongest evidence. It comes from a randomized trial, the kind of study that can show cause and effect.
In a cluster randomized trial in JAMA (He and colleagues, 2015), 1,903 first graders at 12 schools in Guangzhou, China, were split by school. Six schools added one 40-minute outdoor class to every school day. Over 3 years, 30.4% of eligible children in those schools developed myopia, compared with 39.5% in the usual-schedule schools.
How much sleep do children need?
More than most adults think. The American Academy of Sleep Medicine consensus statement (Paruthi and colleagues, 2016) recommends:
| Age | Sleep per 24 hours |
|---|---|
| 3 to 5 years | 10 to 13 hours, naps included |
| 6 to 12 years | 9 to 12 hours |
| 13 to 18 years | 8 to 10 hours |
A child up at 7 AM needs lights-out between about 7 PM and 10 PM. On bedtime early in life, see Does Bedtime Affect Toddler Growth? What a 2026 Study Found.
What are the limits of the 2026 study?
It shows a link, not a cause. The data come from one city in China, at one point in time, with sleep and lighting reported by questionnaire rather than measured by a light sensor.
A child who sleeps with a light on may also read in bed or use screens more. Only a follow-up or a trial can show whether turning off the light protects eyes.
What is the one change to make?
Put lights-out on the plan as a fixed time, with darkness and enough hours of sleep behind it.
- Count back from wake-up: 9 to 12 hours for ages 6 to 12, 8 to 10 for teens. That is the lights-out time.
- Close curtains against streetlights, and switch off the overhead light at the end of the bedtime story.
- Keep phones and tablets out of the bedroom at night; see Does Late Phone Use Hurt Teen Sleep? What a 2026 Study Found.
- Balance it with daylight: a walk to school, outdoor recess and after-school play fill the day side of the plan.
- If evenings have drifted late, see How to Fix Your Sleep Schedule: Anchor, Light, 15 Min.
Any change in a child’s vision is a reason to see an eye doctor; lighting and sleep are habits, not a substitute for an eye exam. Curious when your own body clock runs early or late? Take the Body Clock Type quiz.
Your day on My BodyClock
The day above on My BodyClock shows a school day for a 7-year-old: light by day, darkness by night. Sleep runs from 8 PM to 7 AM, 11 hours, in a dark room. Mornings bring open curtains, breakfast and a walk to school. A 40-minute outdoor recess follows lunch, and an hour in the park comes before homework. After a 6 PM family dinner, a bath and a story under a small lamp end with lights off at 8 PM.
Build your family’s version, with a lights-out reminder, in Owaves: My BodyClock on the App Store, or join the Android waitlist.
FAQ
Is it bad for kids to sleep with the light on?
It may not be harmless. In a 2026 study of 4,571 schoolchildren in China, sleeping with the lights on was linked with myopia, especially when combined with short sleep. It is an association, not proof of cause.
Do night lights cause nearsightedness?
That has not been proven. A 1999 study suggested a link, a 2000 study did not find one, and the 2026 study found an association in school-age children, strongest when a light at night came with short sleep.
How much outdoor time helps prevent myopia?
In a randomized trial of 1,903 first graders in Guangzhou, adding one 40-minute outdoor class per school day cut the 3-year rate of new myopia from 39.5% to 30.4%.
What time should a 7-year-old go to bed?
Children aged 6 to 12 need 9 to 12 hours of sleep, so a child waking at 7 AM would turn the lights out between about 7 PM and 10 PM.
Sources
- Zhang X, Li L, Kang M, Wang M, Peng T, Wang T, Li H, Tu Y, Wang N, Li SM. Light-at-night and short sleep: a synergistic dual threat to myopia in children and adolescents. British Journal of Ophthalmology, published online 26 October 2026. doi:10.1136/bjo-2026-330275. https://bjo.bmj.com/content/early/2026/10/26/bjo-2026-330275
- He M, Xiang F, Zeng Y, et al. Effect of Time Spent Outdoors at School on the Development of Myopia Among Children in China: A Randomized Clinical Trial. JAMA, 2015;314(11):1142-1148. doi:10.1001/jama.2015.10803. https://pubmed.ncbi.nlm.nih.gov/26372583/
- Paruthi S, Brooks LJ, D’Ambrosio C, et al. Recommended Amount of Sleep for Pediatric Populations: A Consensus Statement of the American Academy of Sleep Medicine. Journal of Clinical Sleep Medicine, 2016;12(6):785-786. doi:10.5664/jcsm.5866. https://pmc.ncbi.nlm.nih.gov/articles/PMC4877308/
- Quinn GE, Shin CH, Maguire MG, Stone RA. Myopia and ambient lighting at night. Nature, 1999;399(6732):113-114. doi:10.1038/20094. https://pubmed.ncbi.nlm.nih.gov/10335839/
- Zadnik K, Jones LA, Irvin BC, et al. (CLEERE Study Group). Myopia and ambient night-time lighting. Nature, 2000;404(6774):143-144. doi:10.1038/35004661. https://pubmed.ncbi.nlm.nih.gov/10724157/
- Chakraborty R, Ostrin LA, Nickla DL, Iuvone PM, Pardue MT, Stone RA. Circadian rhythms, refractive development, and myopia. Ophthalmic and Physiological Optics, 2018;38(3):217-245. doi:10.1111/opo.12453. https://pubmed.ncbi.nlm.nih.gov/29691928/
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