Teenagers Might Be Better Off If They Sleep On It


Aarthi Belani still shudders when she recalls dragging herself out of bed each morning during her junior year of high school two years ago in Edina, Minn. The 17-year-old, who will be a freshman at Stanford University this fall, would set her alarm clock for 6:30 a.m., the latest possible time that would allow her to shower and run off to school in the cold and dark with no time for breakfast and her hair still wet.

School started at 7:20 a.m., a common opening time for high schools in the United States. It felt like the middle of the night to Aarthi and her classmates.

“It was an ungodly hour to be studying chemistry or something,” she said. “In first period, 75% of the kids would have their heads down on their desk at one time or another.”

Now a growing body of research suggests that Aarthi’s fatigue and that of her classmates was the predictable outcome of a school schedule insensitive to teenage biology.


Adolescents in their mid- and late teens, it turns out, have a physiological need for extra sleep compared with younger teens, especially in the morning hours. Yet adolescents typically get less sleep as they mature, in part because most high schools start an hour or so earlier than junior-high schools.

Officials in several Minnesota school districts, concerned by the latest research suggesting that sleep deprivation may be taking a toll on students’ academic performance and emotional well-being, are experimenting with bold changes in school starting times. It is an effort to synchronize the school day with adolescents’ biological rhythms.

Preliminary evidence from Edina, where Aarthi and her classmates were allowed to start school at 8:30 a.m. last year, suggests the later schedule is paying off with higher grades, fewer discipline problems and a generally happier, more-rested student body.

“Teachers are saying, ‘This is a remarkable change. The attention that is being paid in my first-hour class is so vast, I can’t get over the difference that one hour of sleep makes,’ ” said Kyla Wahlstrom, associate director of the Center for Applied Research in Educational Improvement at the University of Minnesota, who has studied the logistics of changing school-day timing.

The new findings may be relevant to younger children too.

Research suggests that many behavioral problems in elementary and junior-high school children, including some of the growing number of diagnoses of attention deficit hyperactivity disorder, are in part a result of increasing sleep deprivation.

“The main effects of insufficient sleep at these [younger] ages are behavioral and emotional changes,” said Ronald E. Dahl, director of the child and adolescent sleep laboratory at the University of Pittsburgh Medical Center. “It’s important for parents to realize this, because they can be unaware that their kids are not getting sufficient sleep.”

Discovery Contradicts Conventional Wisdom


The discovery that adolescents have a biological need to sleep a little later in the morning was a surprise to Mary Carskadon, the Brown University sleep researcher who spearheaded early studies of the phenomenon in the 1980s while she was at Stanford.

“The conventional wisdom was, ‘The older you get, the less sleep you need,’ ” said Carskadon, who directs the E.P. Bradley Hospital Sleep Research Laboratory in Providence, R.I.

Her studies of children ages 10 to 17 who were allowed to get as much sleep as they needed defied that wisdom by showing no decline in sleep requirements with age. Given the chance to sleep as much as they wanted, teens slept an average of 9 1/4 hours, leading Carskadon to believe that even if that is unrealistic for many, then they at least ought to get about 8 1/4.

Another series of tests by Carskadon, which measured daytime sleepiness in teens of various ages, found that older adolescents nodded off in the day more easily than their younger counterparts.


“This seemed to say not only do adolescents not need less sleep, but in fact something happens in adolescence that contributes to feeling sleepier in the day,” Carskadon said.

At first, she and her colleagues assumed their findings reflected psychological or sociological aspects of adolescence, rather than a biological need for more shut-eye. Teens, after all, have many reasons to stay up late, any number of which could be contributing to daytime sleepiness.

Indeed, adolescence is a time of great psychosocial upheaval, with many new opportunities and responsibilities to face. Teens commonly are driven by a desire to take control of their lives and to gain independence from parents, for example. And what better way to do so than by staying up late, especially since later bedtimes are recognized as emblematic of adulthood.

Adolescents also have a host of new social options, including evening sports events and late-night outings with friends. Homework also increases in the late teen years, and few parents would argue with the student who wants to stay up late studying.


If factors such as these were the overwhelming source of insufficient sleep and daytime fatigue, the problem would be relatively easy to solve by simply insisting that adolescents go to bed earlier.

However, Carskadon said, “Recently we’ve found that the biology of the system is also pushing them later.”

Specifically, Carskadon and her colleagues have found that as adolescents mature, their biological clocks undergo a hormonal “phase shift” that pushes their pre-programmed period of wakefulness about an hour later than it was in their early teens. The shift is due to a delay in the timing of a nightly squirt of the hormone melatonin from the pineal gland, deep inside the brain.

Melatonin, which induces sleepiness, helps set the body’s circadian pacemaker, or biological clock. For reasons that remain unclear for now, it is secreted at about 9:30 p.m. in young adolescents but at about 10:30 p.m. in older teens.


That change not only delays the onset of sleep, it also pushes back by an hour or so the various phases of the coming night’s sleep. And if the wake-up hour is not also pushed about an hour later, then a key phase of the sleep cycle is truncated: the final hour of dreaming (also known as REM, or rapid eye movement) sleep, which researchers have identified as important to getting the feeling of a good night’s rest.

“A lot of people say, ‘Just put them to bed an hour earlier,’ but it doesn’t work that way,” Wahlstrom said. “Circadian rhythms don’t adjust like that. You can put them to bed an hour earlier and they’ll just stare at the ceiling.”

“There are lots of reasons to stay up later, but the other end is not usually as flexible,” Dahl said. “So what gets squeezed down is the amount of sleep.”

Every Body Needs Sleep


Lack of sleep wouldn’t matter if sleep were the waste of time that some hard-driving “type A’s” presume it to be. Researchers say they still know relatively little about what, exactly, sleep does for the body. But a wealth of empirical evidence indicates that, although sleep requirements vary significantly from person to person, sleep is critically important to everyone.

“Sleep is obligatory,” Carskadon said. “It’s not one of these optional things.” She notes that the devastating nuclear accidents at Three Mile Island in Pennsylvania and Chernobyl in the former Soviet Union have been attributed to human error linked to insufficient sleep, as have countless other mishaps.

Experiments have shown, for instance, that reaction times slow significantly in even moderately sleep-deprived people; it is a factor that has been linked to many traffic accidents and one of the reasons that athletes often are given early curfews on the night before a game.

Equally problematic, sleep deprivation interferes with cognitive functioning--especially “divergent thinking,” the kind that is needed for creative problem-solving. In students, this is the kind of thinking used to answer an essay question, as opposed to the more-linear cogitation that is needed to answer “true-false” or multiple-choice questions.


Recently, a researcher in Carskadon’s lab has documented another consequence of insufficient sleep: an emotional instability or irritability that many people would recognize from their own experience after pulling an all-nighter, but that had not, until now, been documented in laboratory studies.

The researcher, Carol Liotta, showed teenagers several pictures that had previously been rated by others for how intensely the pictures stirred up specific emotions such as fear, anger or happiness. Some of the participants had a full night’s sleep the night before, while others had only four hours of sleep.

Preliminary results indicate that the pictures conveying negative emotions (especially those that prompt feelings of anger, sadness and fear) triggered higher-than-normal negative feelings in the sleep-deprived subjects, compared with the responses from their rested counterparts.

The findings suggest that sleep is a key factor in the regulation of emotions, and especially in the regulation of negative emotions, Liotta reported at a scientific meeting in June.


Similar work in progress in Dahl’s laboratory supports the hypothesis that a lack of sleep may help explain some of the emotional and behavioral problems seen in adolescents.

Dahl notes that adolescence is a stage of life in which the parts of the brain that oversee such adult characteristics as long-term goals and delayed gratification start to gain control over “less mature” regions of the brain that leave children more prone to emotional outbursts.

This emotional maturation is made possible in part by what neuropsychologists call cross-temporal processing, in which a person remembers the past in order to decide what to do in the future. For example, a person might remember that the last time he shouted at his mother he got sent to his room, and so may decide this time to hold his tongue.

Dahl suspects, and preliminary results from experiments concur, that adolescents short on sleep are impaired in their ability to make these adult calculations and are less likely to suppress the childlike emotions they are beginning to outgrow.


“It’s dangerous to generalize,” Dahl said, “but there are large numbers of teens for whom a simple lack of sleep may really tip the balance for having emotional difficulties.”

‘Participants Instead of Zombies’

For adolescents, whose delayed melatonin surge means that critical sleep is often still going on at 7 a.m., findings like these suggest that early school starting times may be resulting in grogginess and lack of attention in class, poor performance on exams and increased odds of behavioral or disciplinary problems.

“Kids are waking up and going to school at a time when their brains are still in the nighttime mode,” Carskadon said. “Even in second period, they are not ready to learn, not ready to be engaged in education.”


That’s why school officials in Edina last year decided to make an unprecedented bid for wakefulness by having its 1,350 students start classes at 8:30 a.m. instead of 7:20. So far, said Wahlstrom, everything suggests the experiment is working.

“Previously, 20% of these kids were sleeping during the first hour of school,” said Wahlstrom, a former teacher, elementary-school principal and school administrator. “Now none are. They are participants instead of zombies.”

The extra rest seemed to have a ripple effect. According to Wahlstrom, administrators got fewer referrals for discipline problems under the new schedule, and the number of students reporting that they were depressed or ill dropped dramatically. “The nurse can’t get over the reduction in the referrals to her office in the mornings,” she said.

The ultimate test, of course, is academic performance, and here the new schedule also seems to be at least a partial success. Student scores were higher last year than in previous years for grades 11 and 12, although there was no noticeable difference in younger students’ grades.


“All the stuff we’re finding in Edina is bearing out the findings reported initially in [sleep lab] studies,” Wahlstrom said.

Last year Wahlstrom conducted research to see what it would take to get a larger region of Minnesota, encompassing Edina and 16 other school districts, to make their starting times later.

She and her colleagues interviewed parents, teachers and students; they spoke with transportation and busing directors; they sat down with athletic coaches, who wanted to make sure the change wouldn’t interfere with team practices or games; they spoke with food service and meal coordinators and with advisors for various extracurricular activities.

It was a massively complicated job. “I was one of the most sleep-deprived researchers you ever met,” Wahlstrom said. But the results were encouraging. “We showed that . . . there’s no inherent reason why it can’t be done.”


One of those 16 districts was changing its schedule this fall, with a modest but potentially helpful delay of about a half-hour for its 2,148 students in grades 10 to 12. Another district will offer a two-tiered system in which the 1,485 students in those grades can choose to start at either 7:30 a.m. or 8:30. (Interestingly, about one-third of those students have opted for the earlier slot, corresponding almost exactly with research findings that about 30% of people are natural “larks.”)

In the biggest and boldest move of all, Minneapolis city schools, which were not part of the survey, will delay their opening time 45 minutes to 8:30 a.m. this year for its students in grades 10 to 12.

“That will really be interesting,” Wahlstrom said. “It’s a very urban school district with all the usual urban problems” of poor academic performance, behavioral problems and after-school crime. “We hope this will increase academic achievement and, with kids spending a little more time in school in the afternoon, maybe lead to less trouble in the neighborhoods.”

Getting to Bed Early Is Key


If follow-up studies indicate that later starting times are indeed helping students, then other districts may follow. But what can teens and parents do for now if the school bus is rolling up at 6:30 a.m. or even earlier, nipping REM sleep in the bud and in many cases making breakfast a weekend luxury?

Most important, experts said, is getting youngsters to bed as early as is reasonably possible. Melatonin timing may make it difficult for adolescents to fall asleep before 11 p.m., but if they go to bed before then, perhaps with a good book in hand, then at least they’ll nod off at the first natural opportunity.

Without strict bedtimes, experts said, adolescents may get fooled by the false sense of wakefulness that often arises between 8 and 10 p.m.

“Some people call it the ‘forbidden zone,’ ” Carskadon said of those hours, “when it is very difficult to fall asleep. That fools people into saying, ‘I feel OK now, I don’t have to go to sleep.’ ” Thus fooled, they become very active and it may not be until midnight that they give themselves a chance to relax again.


Simple as that strategy is, it is rarely used. In a recent survey of more than 3,000 high-school students, only 5% said they had school-night bedtimes set by parents. That may explain why 87% said they relied on either an alarm clock or a parent to get them up in the morning.

For parents or children averse to fixed bedtimes, other tricks can help induce sleepiness at the earliest biological opportunity, such as having a “quiet time” in the evening when lights are kept low and loud music is discouraged. Carskadon eschews pharmaceutical intervention in adolescents, however, including “natural” melatonin supplements, which are available as soporifics in health-food stores.

“In other mammalian species, melatonin is involved in reproduction,” Carskadon said, “and I don’t think we know enough about its effects in the developing human-reproductive system to use it as a supplement in youngsters.”

Occasional late-night indulgences do not have to be a big problem, experts said, most people can “make up” for a single night of insufficient sleep by getting a full night’s rest the next night. But the prognosis changes when sleep loss extends for two or more nights.


Research by Carskadon and David F. Dinges, chief of the division of sleep and chronobiology at the University of Pennsylvania, suggests that teens who stay up very late on Friday and Saturday nights are noticeably more sleepy during the week even if they go to bed at a more reasonable hour during the week. Apparently, Dinges said, regularity of sleep is almost as important as the number of hours of sleep, and the body gets thrown off by differences in weekday and weekend sleep cycles.

Of course, a habitual lack of sleep, regular though it is, is not the answer; in fact, even a modest lack of sleep can take a noticeable toll if it goes on for several nights in a row.

In one recent study conducted by Dinges, adolescents were allowed to sleep only about five hours a night for seven nights, a not-uncommon condition for high-school students. It took a full two nights of recovery sleep for their scores on various cognitive and mood tests to return to normal.

Parents should be aware that it’s not always obvious that their teen-age children are short on sleep.


Rebellion at bedtime may be interpreted by parents as evidence that the child is not in need of sleep; but look for other hints of accumulating fatigue, experts said: Is it hard to wake them up in the morning? Are they cranky or irritable late in the day? Do they fall asleep spontaneously during quiet times of the day, such as while riding in the car? All these can indicate insufficient sleep.

Sleep deprivation can be even more difficult to notice in younger children, who do not display sleepiness in the same ways as adults.

“Younger kids and early school-age kids, in contrast to teens, often don’t look sleepy when they are sleep-deprived,” Dahl said. “They may be irritable or cranky, and may have short attention spans and can’t control their emotions very well. They can look like hyperactive kids or attention-deficit-disorder kids. That’s important to consider when you look at the dramatic increases in these diagnoses in our society.”

No one knows if a fuller and more regular sleep schedule would help children found to have behavior problems such as attention-deficit-hyperactivity disorder, but Dahl and others believe many such cases could be prevented before they occur if sleep patterns were better in the first place.


“Once adolescents are stuck in the cycle of poor self-image and struggling with schedules and emotions then they may dig themselves down and they may need a whole set of things,” Dahl said. “Prevention may be far simpler.”

Even if a child is already entrenched in a cycle of sleepiness and irritability, however, a regimen of regular and reasonable enforced bedtimes may help.

“If you’re even suspicious that lack of sleep is a problem, why not try it for a week or two?” Dahl said. “Lots of families say, ‘Hey, it’s a different kid. He’s happier, calmer, in better control.’ So if there is any doubt, why not do the experiment and try?”