At 17 months of age, my son Alex is put to bed at 8pm and usually wakes up around 7.30am. Coupled with a nap or two during the day, he easily gets his recommended 12 hours of sleep. But upstairs, our neighbor’s toddlers bounce on our ceilings until at least 10pm on most nights. Many Chinese parents tell me their child goes to bed at 9, 10, or even 11pm.
An American Academy of Pediatrics study from 2005 confirms that Chinese children not only go to sleep later than American children, they also wake up earlier: Chinese children in elementary school sleep a full hour less than American children (9.25 vs. 10.2).
The main issue isn’t what time your child goes to bed but rather their total hours of daily sleep including naps, which very few kids over 5 take. Preschoolers need 11-12 hours of sleep, school-aged children need at least ten, and teens need nine to ten. By comparison, infants need 16-18 and adults need seven to eight. If your 5-year-old goes to bed at 9.30pm, wakes up at 6.30am, and doesn’t take naps, their nine hours of sleep isn’t enough to ensure long-term health.
A fascinating series of tests published this year focusing on school-age children in China shows that insufficient sleep and daytime sleepiness can worsen school performance. Most of these students go to bed at 9 or 9.30pm and almost all of them get up at 7am, causing a daily sleep debt of 30 minutes to one hour. While this may seem small, most children cannot recover the deficit by sleeping late on weekends. Over time, this can affect attention span, motivation, and achievements on tests.
The good news is that delaying school start times by just 30 minutes can significantly improve sleep quality. In the same study, delaying school openings from 7.30am to 8 or 8.30am gave students almost an hour of extra sleep. This dovetails with other studies that support the growing movement by pediatricians to delay start times to 8.30am.
Besides academic performance, poor sleep also increases the risk of childhood obesity. A 2007 meta-analysis of 36 studies from across the world shows a strong, independent association between inadequate sleep and weight gain in children – an association that continues into adulthood.
There may be a physiological basis to this, as inadequate sleep affects the hormones that control appetite, intensifying our instinctive hunger reflex. While this isn’t a cause-and-effect relationship, the association is worrisome.
Though I can’t control the noisy kids upstairs, I’m glad that we’re teaching Alex good sleep habits. When we choose schools in the future, we’ll definitely consider later start times a positive factor.
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