Monday, October 15, 2007

Po on "On Point"

From Ash:

This morning, Po was on the NPR show On Point discussing our sleep pieces. Also guests were Dr. Judith Owens, of Brown University, and the new superintendent of schools for Edina, Ric Dressen.

I think it's a really great discussion of the issues we've been writing about.

You can download the audiofile from the On Point program information website.


Wednesday, October 10, 2007

Naps and Other Make-up Sleep

From Ash & Po:

A couple people have asked us about naps (for school-aged and older kids) and sleeping in – great questions we'd wondered, too.

If your kid is tired, then, by all means, let the kid sleep in or take a nap.

Let's kill the myth that sleeping in or napping is part of "lazy afternoon." Physiologically, you can't sleep unless you actually need to sleep. That's the homeostatic pressure part of sleep at work. So there's nothing lazy about getting needed sleep. (Conversely, being awake and sleep-deprived will probably lead to more lethargy than if he'd actually just slept more.)

Moreover, sleep loss is cumulative, so the only way to make up for it is to get more sleep on another night or during a nap.

But – and this is the big caveat – don't treat sleeping in or naps as a cure-all. Instead, they are the sleep-equivalent of band-aids. They shouldn't be something that you rely on, instead of having a kid get a regular nightly sleep schedule.

Here's why.

Sleeping in and naps do help resolve the sleep debt, but they probably won't resolve the debt entirely. As an example, let's say that a particular teen does need the 9.25 hours a night recommended by many sleep experts. But he only gets seven hours on school nights. On Monday, he's down 2.25 hours. That's not great, but we've all been there, right? By the end of the week, he's short 11.25 hours of sleep – he's missed more than an entire night's worth of slumber. Even sleeping in until noon on Saturday will probably only have helped erase two or three of those lost hours.

Much more daytime sleep than that, however, will likely throw off a kid's circadian rhythm and homeostatic pressure – so he'll may have more trouble going to sleep in the evenings, and wake up already sleep-deprived the next Monday morning. (That's even more of a concern for a teen, whose circadian system already has a preference for nighttime wakefulness.)

The amount and quality of sleep a person needs in a given night is directly related to the mental and physical activity that a person did during that very day. To the point that if you learn more vocabulary, you likely will spend more time in REM stage sleep. Make-up sleep can't handle those sleep stage adjustments as well.

Naps also bring unique problems of their own. That horrible groggy feeling after some naps is called "sleep inertia" – the body can't wake up fully. That's a real issue, but scientists don't know why it occurs or what it means.

What they do know is that the brain can't do the same sort of work during a nap that it does during nightly sleep. Consider that a nice nap is about 25 to 45 minutes. That's only 1/4 to 1/2 as long as it takes to cycle through all of sleep-stages of non-REM and REM sleep, and the brain needs to process information throughout all the stages of sleep.

Interestingly, a nap works best if it's prophylactic: if you know the kid's going to have a late night, then an afternoon nap can help him stay alert later in the evening. But even that is of limited use: he'll be just as tired the following day as if he hadn't had the nap.

Ultimately, let them get that make-up sleep.

But the more make-up sleep they need, the more you should think about changing their overall sleep schedule.


One Real Cost We All Pay For Sleep-Deprivation

From Ash:

There's one aspect of sleep deprivation for adults that I think is so important, that I really think that if this blog post could be forwarded around enough, it could help save lives.

A study for the National Highway Traffic Safety Administration reported that, between 1999 and 2003, drivers falling asleep at the wheel were responsible for an estimated 1.35 million car accidents.

Sleepy drivers are just as impaired in reaction times and judgment as drunk drivers – to the point that the experts can actually give you equivalent blood alcohol measurements depending on how much sleep deprivation you've had.

But that's just a "drowsy driver."

A driver who actually falls asleep is even more dangerous than the drunk driver. Because if she's asleep, she's never going to hit the brakes, turn the wheel, or take any evasive action. The car just keeps going forward until it runs into something. So a fall-asleep crash is almost always serious and rarely just a fender-bender. Statistically, "fall-asleep accidents" are actually much more deadly than other types of crashes.

As we wrote in an earlier post, young adults, who are the most sleep-deprived, are disproportionately responsible for sleep-related car accidents: young adults are involved in 55% of the 100,000 fall-asleep crashes annually, even though they aren't even close to being half of the driving population.

Now, if you just did the math and realized that the national studies' numbers aren't consistent, that's because the 100,000 accident rate is based on police reports. But the police determine that sleep was the culprit only when they've ruled out every other reason for the crash to have occurred. So, for example, they rule out weather, alcohol, mechanical failure, etc. until there's no other possible explanation than the driver fell asleep. Thus it's a low estimate.

The 200,000+ accident annual figure comes from a nationally representative survey that asked people about their driving habits and sleep-related crashes. Not surprisingly, drivers were more willing to confess to fall-asleep crashes to the researchers than they were willing to admit to the police.

That's the kind of question that usually has an artificially low response though – because people don't like to admit that they are to blame for an accident. So that too, is a low estimate.

So how big a problem is this, really?

A couple of the sleep experts privately told me that if the real figures were known, we'd discover that more young people die in fall-asleep crashes than drunk-driving accidents.


Sleep Is For Wusses – An Idea Kids Are Learning All Too Well

From Ash:

Between Po and myself, I think we have interviewed at least 20 of the world's sleep experts.

Every one of them complained that exhaustion is a huge national health-issue. And every one of them also railed against the way our society sees that exhaustion as a virtue.

Indeed, our 24-7 society doesn’t tolerate sleepiness. We don't think of sleep as a biological imperative. Instead, we think of it as a character flaw – a sign of weakness. University of Minnesota's Dr. Mark Mahowald says that he's even heard parents say that exhaustion is actually good for children – because it teaches them a good work-ethic. Continuing with this logic, the parents actually argue that getting enough sleep would actually be bad for children, because valuing sleep would teach kids to be lazy. If nothing else, they argue, sleep deprivation will prepare kids for the exhaustion they'll face as adults.

Perhaps most tellingly – these parents also say that if they're tired, then their kids should be, too.

That’s what it really comes down to. For adults, sleep has become a luxury good; it’s considered an indulgence, not a necessity. And I'll be the first to admit that I myself have had that point of view – I'm one of those "Sleep When You're Dead" girls. Even as I've slathered the concealer on, trying in vain to cover up the circles under my eyes, I've considered those dark shadows as badges of honor.

We sell a story to ourselves that Sleep is for Wusses. And apparently, our kids buy into it, too.

For the past several years, a childhood friend of mine, Bridget Persons, now a San Diego, California high school English teacher, has given her students a district-mandated final exam. The students are supposed to read a couple articles on teens’ need for sleep, and then they're to write a persuasive letter to the Board of Ed as whether or not school start times should be changed.

Bridget’s school starts at 7:15 am. To get there, many of her students are already on school buses at 6am.

Her students never miss the irony. They’re taking a 7:15 am final exam about how teens’ brains are still asleep at 7:15. Between the readings and their own experience, the students are convinced that there’s a problem. They feel passionately enough about it that they always get into a big discussion after the test.

But out of hundreds of student essays she’s read, Bridget says only one student ever asked for more than a scant 15 or 30 more minutes of sleep.

They have this gut instinct that (correctly) even just 15 minutes or so more would help a little.

The kids all want even more sleep than that – they feel it would make a real difference – but asking for more than that just isn't something they feel they can do. Practically, they just can’t figure out how to fit sleep into their busy lives. Their school is a performing arts magnet; rehearsals frequently last until 8 pm. Home at nine with homework to do, an extra hour of sleep is an extravagance well out of their reach.

I don't know what grades they are getting on those essays, but it's clear that they’ve already mastered society's lesson: The show must go on.


Tuesday, October 09, 2007

On the Question, "How Much Sleep Does My Child Actually Need?"

From Po:

You might notice that in both of our sleep articles, we never come out and say, "here's how much sleep your kids needs - X hours." I don't think there's an easy answer to this, and I don't like pretending there's an easy answer when in fact it's complicated. Perhaps I'm most worry of the simple advice line, "your 5th grader needs 10 hours of sleep," because I don't think merely telling people this nugget will have any affect at all. I might as well be telling people "you need 5 million dollars to be financially secure." That isn't going to help them get from point A to point B - from where we are today, to where we need to be. So I emphasized, in the article, how every 15 minutes counts, and how a single hour can have dramatic consequences. I'm hoping the integrity of that science will push parents and children to find 15 minutes more, or a half hour more.

For the record, here's a simple chart we made which shows the gap between "what kids need" and "what they get." It uses data from Dr. Fred Danner at the University of Kentucky.

According to the sleep scientists, one of most-common incorrect assumptions is that you could draw a straight line from how much sleep your 6 year old needs to how much sleep an adult needs, and plot kids along that slope by age. I.e., as kids get older, they don't need as much sleep. While there's some slope from age 6 to age 12, the sleep scientists say that all teenagers, ages 12-18, really need 9.2 hours sleep. Their brains are still developing up until about the age of 21 (during later teen years, their brains appear to be pruning away unnecessary synaptic connections in the prefontal cortex, and this seems to improve their judgment of risk). At the end of puberty, the "phase shift" of delayed melatonin ceases.

How do the sleep scientists know that kids need 9.2 hours? Well, here they make a crucial assumption. They assume the body and brain will wake up when they've had all the sleep it needs. So they say teens "need" 9.2 hours by having experiments where the kids sleep a ton for weeks before coming into the sleep clinic - so they're entirely rested - and then letting them sleep all their bodies want in the clinic. The teens slept over 9 hours. In fact, at that point the researchers did wake up many of the kids.

So that might be how much the body wants, but is it fair to say that's what the body/brain really, truly needs? The scientists believe so. On the other hand, it's also fair to ask "at what point do we see a steep dropoff in performance, due to less sleep?" Is there a tipping point? The answer appears to be that we see minor consequences for only getting 8 hours sleep, but we see major consequences for only getting 7 hours sleep. One study of over 3,000 students in two school districts in Ontario, Canada demonstrated this dynamic. We didn't include this study in our New York article because the data is literally too hard to explain in just a few words, and you'll see why. Basically, they asked kids if they felt sleepy in the morning. 73% of the kids felt sleepy from 8 am to 10 am. They were performing worse than the "not sleepy" kids, but only slightly worse, nothing alarming. However, there was an additional subgroup who still felt very sleepy from 10am to noon. This group had real problems, from decreased grades to missing school and sports, etc. The rate of "sleep consequences" skyrocketed up 46% to 220%, depending on the variable. They were also getting less sleep - under 7.5 hours.

None of this can be taken as a rule and applied to individual kids. Some people need more, some need less. In sleep clinics there are children getting 11 or 12 hours sleep, yet it's still not enough. And we all have heard stories about a few uniquely driven adults who seem to thrive on 5 hours sleep.

One of the most interesting sub-analyses is being done by Dr. Oskar Jenni in Zurich. He has some preliminary data which, in a strange way, confounds the odds that students who get A's average 15 more minutes than the B's, who in turn average 15 more minutes than the C's. Despite those overall odds still holding true, Jenni has noticed that many very-gifted children actually need less sleep. He theorizes that smarter people actually can sleep less, because they have more efficient sleep systems. The more they sleep, the better it is for them - but they can do more with less, compared to others. (Note: this is very preliminary and untested. Please do not use it to justify letting your gifted child stay up late.)


Monday, October 08, 2007

Are the Hallmark Traits of Adolescence Just Symptoms of Sleep Deprivation?

From Po and Ash:
(Note: This post continues the conversation from our New York magazine stories)

Stephen Farrell is Assistant Headmaster and Dean of Faculty of the elite prep school, Choate-Rosemary Hall. Traditionally, boarding schools hold classes six days a week, but recently, Farrell led the movement to make a controversial change that separated Choate from its peer schools – Phillips Exeter, Groton, and the like. Choate eliminated Saturday classes. Farrell did so for one reason. His students were exhausted. Farrell had seen enough of the sleep research (and heard enough complaints from the school pediatrician) to be convinced that his students’ academic and physical well-being would improve if they slept in an extra day a week.

Even after the switch, Choate’s staff pediatrician regularly warns Farrell that some students are so sleep deprived that they are jeopardizing their physical and psychological welfare. Farrell has tried to tinker with lights-out policies in the dorms and forbidding use of phones and computers use after midnight, but the complaints are too loud from parents, faculty, and students. “These are kids who don’t want to be reined in,” Farrell explained. But they’re not inhuman. On confidential surveys, his students report crashing on holidays, sleeping 15 hours a night during the entire vacation.

While all kids are impacted by sleep loss, for teenagers, sleep is a special challenge.

University of Kentucky’s Dr. Fred Danner has studied how, on a national level, sleep decreases each year during high school. In their first year, 60% of kids got at least 8 hours on average. By the second year, that was down to 30%. Right alongside this decline went their moods; dropping below eight hours doubled the rate of clinical-level depression. Over one-eighth of the students reached this classification, which makes one only wonder how many more suffer from melancholy of a lesser degree.

Brown University’s Dr. Mary Carskadon has demonstrated that during puberty, the circadian system – the biological clock – does a “phase shift” that keeps adolescents up later. In prepubescents and grownups, when it gets dark outside, our brains produce melatonin, which makes us sleepy. But adolescent brains don’t release melatonin for another 90 minutes. So even if they’re in bed at 10 p.m (which they aren’t), they lay awake, staring at the ceiling. It's possible that this played some evolutionary role, back when teens needed to leave the tribe and explore or hunt.

Awakened at dawn by alarm clocks, teen brains are still releasing melatonin. This pressures them to fall back asleep – either in first period at school or, more dangerously, during the drive to school. Which is one of the reasons young adults are responsible for more than half of the 100,000 “fall asleep” crashes annually.

“We thought the evidence was staggering,” Carole Young-Kleinfeld recalled.

Kleinfeld is a mother in Wilton, Connecticut, thirty miles up I-95 from New York City. Wilton, too, had saved money by running busses in two shifts, starting the high school at 7:35. Then a few years ago, she was at a meeting for the local League of Women Voters. Then-state senator Kevin Sullivan spoke about Carskadon and others’ research, and how starting high school at a more reasonable hour was the answer.

Kleinfeld had a sullen teenager of her own, and when she went to local high schools to register kids to vote, she regularly saw students sleeping in the halls during class. So the idea hit home. She and others formed a committee to learn about the issue. Eventually, they convinced the district to move the high school’s start time to 8:20.

For Kleinfeld, the change “was a Godsend.”

Her son Zach had once been a perfectly happy kid, but when he hit high school he became the prototypical disengaged, unenthralled-by-everything teen. He was so negative, so withdrawn that “I really thought we’d lost him,” Kleinfeld sighed. “We’d lost that sense of connection.”

After the high school start time shifted, Kleinfeld couldn’t believe it. “We got our kid back.” Zack would bound downstairs in the morning with a smile, wanting to share a funny story he’d read in The Onion. His SAT scores went up, too.

Several scholars have noted that many hallmark traits of modern adolescence – moodiness, impulsiveness, disengagement – are also symptoms of chronic sleep deprivation. Might our culture-wide perception of what it means to be a teenager be unwittingly skewed by the fact they don’t get enough sleep?

University of Pittsburgh’s Ronald Dahl agrees, observing: “Is it adding one percent or sixty percent, we don’t know. But clearly a lack of sleep makes it much worse.”


Sleep - Without Snooze, You Lose

From Po & Ash:

Today, we have two new features for New York Magazine in which we explore the fascinating – and surprisingly scary – ways that sleep deprivation can affect a child's cognitive, emotional and physiological development. And very early this morning, Po was interviewed about the pieces by Harry Smith on CBS's The Early Show. (Yes, Po's currently slightly sleep-deprived from getting up at 4 am to be interviewed about sleep deprivation.)

We're very excited about these pieces, and we really hope that you'll read both. The main article, Can A Lack of Sleep Set Back Your Child's Cognitive Abilities? (available both in the print and on-line edition of the magazine) is an overview of the effects of sleep deprivation on children. The second, a web-exclusive, How To Get Kids To Sleep More, isn't just your standard advice piece: in that one, we provide the scientific basis for the experts' suggestions on how to get a good night sleep – and explore what we often do that inadvertently prevents getting sleep.

Because we all know that sleep matters. What's amazing is just how much it matters. Sleep isn't just a time of rest – it's when learning is consolidated in the brain, it's when the body's metabolism works its magic, and when emotions are regulated.

Over the next few days, we're going to be blogging more information about both kids' and adults' sleep, so please come back for much more.