My husband and I did the unthinkable the other night: we watched four back-to-back episodes of Mad Men (season 2 is on DVD—hurray!) and still got to bed by 11:30. So why is this a big deal? Well, our two young children aren't particularly fond of sleep, and with the summer sun shining till 9, their bedtime has crept later, leaving little time for such grown-up pursuits. On this particular day, however, the kids were practically begging for bed after an afternoon spent splashing about in a pool. They were in bed by 7:15 and asleep within minutes, leaving Mom and Dad with some unexpected TV time.
Like many parents, I've noticed that vigorous days frequently mean earlier and easier bedtimes. It makes sense, after all, that kids will be more tired and ready for sleep if they've been physically active during the day. Now researchers have done a large study published in the medical journal Archives of Disease in Children to put these parental observations to the test.
The study included 519 healthy 7-year-olds from New Zealand, who each wore a device called an actigraph for 24 hours. An actigraph records movement, providing an objective measure of a child's activity level and sleep time. Parents also noted when their child went to bed, which allowed researchers to calculate how long after bedtime children actually fell asleep.
The researchers found a wide variation in how quickly children fell asleep, with some taking as little as 13 minutes and others needing more than 40 minutes after going to bed. Within this range, there was a close relationship between the onset of sleep and daytime activity. On average, children took an extra three minutes to fall asleep for every hour they weren't moving about. Also, the children who fell asleep faster slept longer overall. On average, children got one extra hour of slumber for every 11-minute drop in how long they took to get to sleep.
This study is part of a growing body of research looking at kids and sleep. We know that getting enough shut-eye is important for children, with studies linking a lack of sleep to poorer performance in school and a higher risk of obesity and other health problems. Studies also show that up to 1 in 6 parents of school-aged children say that their child has difficulty falling asleep. This may lead to poor sleep habits, such as watching TV in bed and going to bed later, which can mean less sleep overall.
What you need to know. What I found most interesting about this research was how closely daytime activity was tied to the onset of sleep. Kids didn't need to be extremely active to fall asleep faster. Instead, their time-to-sleep fell incrementally as their daytime activity increased. So even modest changes in activity (for example, walking to school rather than driving) might affect how quickly a child falls asleep—not to mention their overall fitness.
—Sophie Ramsey, patient editor, BMJ Group
If your child isn't sleeping or getting to bed on time, find out how good sleep hygiene can help. Read more on the link between lack of sleep and ADHD, and find out which treatments (subscribers only) will help your child get a good night's sleep. And for more news and research on children's health, sign up for our free Child & Teen Health e-mail updates.
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