When my three-year-old hasn’t slept enough, I can tell he has a harder time concentrating and working (on a puzzle, a Lego spaceship, or a coffee table-turned Piston Cup racecar matchup) without getting frustrated or distracted. On the other hand, when he’s rested, he has patience and focus, and he tries new creative solutions when something doesn’t fit.
With the school year starting, many of us are mulling over the question of how our little ones learn best. But a growing body of research tells us that how kids sleep may be as important to their learning as the types of challenges and stimulation they’re exposed to during the day. Mounting evidence shows real, measurable differences between the high-functioning brain of a well-rested child and the sluggish autopilot brain of one who is sleep deprived. Those differences have a significant impact on our little ones’ ability to grow and succeed.
The data linking sleep and sharp thinking is extensive. For example, in one study, researchers took a sample of children and asked approximately half to go to sleep slightly earlier and half to stay up later. The average difference in sleep between the two groups was one hour. After three nights, the groups were given a test of neurobiological functioning, and those who had slept an hour less performed equivalent to children two years younger. In other words, one hour of sleep gave the kids two years of brainpower.
Part of the explanation for this is that after sleeping less, one of the first regions of the brain to take a hit is the prefrontal cortex – the area we rely on for invaluable skills like decision-making, creative power, and the ability to remember and use the information in front of us. Kids need these sophisticated tools whether they’re at the language table at preschool or playing tea party at home.
Contrary to popular belief, it’s not necessarily that sleep rests the brain for tiptop functioning the next day; sleep is an active and busy process that builds a more competent brain while it’s happening. For example, with our little ones curled up dreaming of fire trucks, memories may be shuttled around and consolidated, and important connections between brain cells strengthen – making it possible for all the hard work our kids do during the day to settle in and find a permanent home.
That our children need to sleep a lot is a well-known fact, and one that’s usually pretty clear from their droopy, fragile, or even hyperactive behavior when it doesn’t happen. Toddlers need 12 to 14 hours a day until they’re three; preschoolers need 11 to 13 hours until they’re five; and until the age of 10, kids need 10 to 11 hours a night.
What’s less well understood is how much of that sleep needs to be continuous. Last month, a study in the Proceedings of the National Academy of Sciences showed that broken sleep could interrupt important brain processes needed for remembering information. Scientists looked at how mice remembered objects after they had been woken up every minute or two during the night. The ones who were woken up frequently forgot the objects they had seen the day before, while the ones with more continuous sleep had intact memories. Waking up every minute might seem extreme, but according to the scientists, mice naturally sleep for only a few minutes at a time, so a minute is long proportional to their total sleep. The same Stanford scientists have shown that fruit flies need to sleep for 30 minutes uninterrupted in order to preserve memories for the next day.
Luckily, our children don’t wake up every minute during the night, but the studies hint at the fact that memory processing requires stretches, not bursts, of sleep – how long the critical stretches are for human children isn’t clear. But researchers suggest that solid sleep may give the brain enough time to replay memories for storage, or that certain proteins needed for strengthening neural connections may get turned on during continuous sleep.
The two most important predictors of quality sleep in kids: an early bedtime at a consistent hour every night. When we go to sleep at the same time repeatedly, the body’s circadian rhythm has a chance to regulate. Of course, none of us is perfect here – for example, bedtime tends to creep later on Friday and Saturday – but according to sleep experts, it’s better to try and keep the early time even on the weekends as much as possible.
And if sleep is a busy processing time for our children’s minds, it could be that the more they learn during the day, the more sleep they need at night. In turn, with a good night’s sleep, they’re ready to take on bigger challenges – it’s a cycle of sleep and learning that builds on itself. The best we can do as parents is give our kids as much consistent and quality sleep as possible so their brains are ready to take on the work of the next day.