Please, Please Go to Sleep

Here’s what a child’s bedtime looks like to couples expecting their first baby: the nursery is softly lit, the child is sweetly sleepy, the last page of Goodnight Moon has been read. After that comes the final tuck-in, the gentle kiss and, finally, the quiet tiptoe out of the room.

So how often does this happen after the kids arrive? The answer–rounding to the closest zero–is, well, zero. Or at least that’s the way it seems. Wartime over bedtime is as fixed a part of childhood as teething and potty training, except that it goes on much, much longer and is much, much more exasperating. It’s not for nothing that last year’s exquisitely titled faux children’s book Go the F— to Sleep reached No. 1 on the Amazon.com best-seller list a month before it was released. But the battle to get kids down for the night does not just drive parents to distraction; it causes them to worry. Children of all ages need a fixed amount of sleep every night, right? So what happens if your kids consistently fail to get theirs?

This is surely not the first generation of parents to fret about these things. It’s not even the first generation to believe that all the new technology surrounding–and overstimulating–their kids is making the problem worse than it’s ever been. According to a recent study from the University of South Australia, the issue has been debated for at least 100 years, and while eras may pass and the recommended hours of sleep may change, one thing remains stubbornly consistent: kids do not get as much as professionals think they should. The question is whether the professionals are right.

The Australian study, published in the journal Pediatrics in February, began as a straight-ahead exercise in scientific spelunking, with investigators looking for every population-wide paper about kids and sleep duration published from the end of the 19th century through 2009. They discovered more than 200 of them–with one French study dating all the way back to 1897–and two trends were immediately evident.

First, the amount of sleep recommended for every age group has declined steadily over time, dropping an average of 0.71 minutes per year. Now, 0.71 minutes is only about 43 seconds, which does not amount to much over the course of a night. But over 112 years, that adds up to one hour and 20 minutes–and that’s not nothing. At the same time, the amount of sleep that kids were getting was keeping almost perfect pace, dropping about 0.73 minutes per year. No matter how low the recommended-sleep bar gets, children have never quite cleared it.

Another constant: societal hand wringing over children’s lack of sleep and a tendency to blame the hectic pace of modern living. As far back as the late 1800s, an editorial in the British Medical Journal attributed increasing sleeplessness to the stress and hurry of everyday life, made worse by the gaslights and trolley cars suddenly filling the streets. In 1905 one study noted that “this is a sleepless age and more and more … we are turning night into day.” Says Tim Olds, a professor of health and sciences at the University of South Australia and the senior author of the new study: “Throughout the 100-year period, we have been blaming whatever the new technology is–radio, TV, the Internet. Information is coming in so fast that we never wind down.”

Consistent over time, too, is the parental belief that kids need a sufficient amount of sleep in order to grow. This, it turns out, is not just a myth. Studies show that about 60% of a child’s growth hormone is secreted during sleep. “What we don’t know,” says Jodi Mindell, associate director of the Sleep Center at the Children’s Hospital of Philadelphia, “is if a child doesn’t get enough sleep, do you lose that secretion, or does it just shift to daytime?” What’s clearer–and a relatively new finding–is that getting too little sleep appears to have a role in obesity. One Israeli study found the effect in babies as young as 6 months.

So if everyone agrees on the value of sleep, why is the recommended amount always in flux? The troubling answer, according to Olds and his colleagues, is that those recommendations are for the most part subjective. “Every so often, a group of blokes get together and say, ‘What do you recommend, boys? Should we push it up to 9 hours, 15 minutes?'” says Olds. “It really is like that, honestly. It’s an arbitrary public-health line in the sand that people draw.”

Plenty of researchers disagree with this–and do so vehemently. Olds’ research, which he considered “quite innocuous, something of a cameo study, really,” has generated a flurry of controversy, with no fewer than 78 sleep experts and practitioners deriding his scholarship as “a great disservice to children and families” in a Feb. 18 response in Pediatrics. Others have sent him fan mail. People view sleep, he says, as “a lightning rod for their troubles.”

There’s more than just professional bickering involved here. The fact is, sleep is a notoriously tricky thing to study. Every individual’s physiology is different, and just knowing how much sleep a child gets is not the same as knowing how much that child needs. Ten hours may be too little for one 8-year-old and too much for another. And the best research tool yet discovered–asking a child, Do you feel sleepy?–lacks a certain objective rigor.

Still, Canadian research has found that as many as 68% of teens report feeling “really sleepy” between 8 a.m. and 10 a.m., and 23% suspect their grades have suffered as a result. But both adults and kids go through cycles of high and low energy during the day, which can reflect when you last ate, the particular activity you’re engaged in at any given moment and a host of other variables. The key metric should not be how many hours of sleep you logged the night before but how many you need to perform at your peak, and there’s almost no data about that–in part because of the ethical implications of depriving subjects of sleep and then sending them to work or to school. “We’re not saying kids don’t need more sleep,” says Olds. “My hunch is, yes, they do. But we haven’t seen good evidence of that.”

None of this stops the 21st century descendants of 19th century scientists from issuing sleep guidelines of their own. According to the National Sleep Foundation in Arlington, Va., babies from 3 to 11 months should sleep for a daily total of 14 to 15 hours, and toddlers 1 to 3 years old should get 12 to 14 hours. Preschoolers need 11 to 13 hours, and elementary schoolers need 10 to 11. Older children and teens require a minimum of eight hours, which can come as a surprise to parents whose teens seem to sleep all the time. In fact, kids in that age group may simply be shifting their internal clocks, going to bed in the wee hours and getting up at noon. Most teens emerge from this vampiric stage none the worse for it, though parents should try to keep things from getting out of hand. “It’s best to keep them in the proper time zone,” says Mindell.

A final wild card in all discussions of sleep duration is the way guidelines change from country to country. Australian children, for example, sleep almost a full hour per day more than American kids, who sleep less than kids in nearly all other countries. And different cultures have different tolerances for sleepy children. In Japan it’s more or less accepted that students sometimes doze off in class because they’ve stayed up late studying the night before.

The best advice for parents, as with so many things, is simply to know your kids. Observe their body clocks by noting how long they sleep on weekends and holidays when there’s no need to get out of bed for school. Track their grades as they sleep more or less. And above all, try to stay calm. They do eventually go the, er, heck to sleep. Just never as easily as Mom or Dad would like.