As most high school teachers know, some students just can't seem to stay awake in class, no matter how stimulating the lesson may be. Teachers often put it off to laziness or blame parents for failing to enforce a reasonable bedtime. But new research out of Brown University says the real culprit may be biology.
Mary Carskadon, a professor of psychiatry and human behavior at Brown's school of medicine and director of the sleep research laboratory at E.P. Bradley Hospital in Providence, R.I., is so sure of her findings that she thinks high school administrators should push back the start of the school day to let students get another hour or two of sleep. "These kids,'' Carskadon says, "may be being asked to function at the wrong time for their bodies.''
Carskadon, who is considered the preeminent researcher in adolescent sleep patterns, has been studying the effects of early morning schedules on teenagers. At a more basic level, she and her colleagues are trying to learn more about how puberty affects youngsters' sleep needs and patterns. What they are learning suggests that teenagers may need more sleep than they did before puberty, not less, as commonly thought.
Sleep patterns change during adolescence, as any parent of a teenager knows. Most adolescents prefer to stay up later at night and sleep later in
the morning. But what Carskadon and her colleagues have learned is that this shift is not necessarily a matter of choice; their bodies are going through what the researchers call a "delayed phase preference.''
This shift in sleep patterns, Carskadon is convinced, makes the transition from middle school to high school--where the day often begins an hour earlier--all the more troublesome. With their need for more sleep and their internal clocks increasingly set on a "go to sleep late, rise late'' mode, adolescents are particularly hard hit by a 7:30 a.m. starting bell. A nap, be it on a desktop or elsewhere, she says, may be their body's way of saying, "I need a timeout.''
To hear Carskadon talk about it, sleep is the Rodney Dangerfield of human biology: It doesn't get any respect. "There's no concept that sleep plays an important role,'' she says. "It's the last thing people think about.'' Indeed, sleep isn't even mentioned in the Carnegie Corp.'s otherwise comprehensive report on the teenage years, At the Threshold: The Developing Adolescent. People need to think of sleep as "one of the fundamental foundations for good health,'' the researcher argues. "It helps give synchrony to the day.''
Last year, Carskadon and Amy Wolfson, an assistant professor of psychology at the College of the Holy Cross in Worcester, Mass., worked together on a study of 15 students making the transition from 9th to 10th grade. Early results show that the teenagers were getting less sleep as 10th graders than they did the year before. As 9th graders in
junior high, their day began at 8:25 a.m. As 10th graders in high school, they had to be at school by 7:20. According to the researchers, the high school students weren't staying up later. In fact, they were going to sleep at about the same time as before, but the sleep deficit caused by having to get up earlier made many drowsy at school.
The youngsters participating in the study were encouraged to nap several times during the day to test for what the researchers call "sleep latency.'' The researchers timed the students to see how long it took them to fall asleep. It didn't take long. On average, 9th graders fell asleep in 9.5 minutes and 10th graders in 8.4 minutes. The sleepiest 9th grader nodded after 5.1 minutes, while the most exhausted 10th grader dozed off in only 1.8 minutes.
Four of the 10th grade students, the researchers found, fell asleep in less than five minutes. And, in a finding that impressed the team, one of them went right into "rapid eye movement''--or REM--sleep. Someone who falls that easily into REM sleep, which is associated with dreaming, is sleep-deprived, according to Wolfson. "People shouldn't be falling asleep so quickly like that during the day,'' she says. "These kids are likely to be the ones falling asleep in class.''
Natalie Burrows, an 11th grader at East Providence High School, was one of the students who participated in last year's study. A night person, Natalie found the transition from 9th grade, which started a 8 a.m., to 10th, which started at 7:15, a tough one. "The fact that I stayed up late had more of an effect because I had to get up earlier,'' she recalls. "The first hours of school I'd be dead. Going toward lunchtime I was fine. It was just that first hour and a half that was terrible.''
The two researchers are continuing the study this year with another group of students.
Carskadon has made researching adolescent sleep the centerpiece of her 25-year career. But a turning point of sorts came several years ago when she and her team launched a study of the sleeping patterns and preferences of 6th graders.
In January 1991, Carskadon, seeking subjects for the study, placed a request for volunteers in the teacher's guide of a science magazine for 4th though 6th graders. Sixth graders at 36 schools ultimately took part in the project. The team targeted 6th graders because they wanted students who would be close in age and psychosocial experiences but span stages of puberty. The study group numbered 183 boys and 275 girls.
The youngsters filled out questionnaires that asked everything from what bedtime they would pick if their parents let them choose to what time of day they have the most energy to do their favorite things. In the end, the team found that puberty had a significant influence on the youngsters' tendency to stay up late and get up late. The pattern was most pronounced in girls. Carskadon and her team presumed that this was because a higher percentage of girls in the study group had matured into puberty than boys.
The idea that the later sleep pattern may be brought on by biological factors was a departure from conventional thinking on the topic. Many in the field had thought psychosocial factors--such as peer influences, the reach for independence, rebelliousness, or more homework--were behind the change.
But if a factor such as peer-group pressure was in fact part of the cause of the shift, 6th graders in a middle school setting (as opposed to an elementary school setting) would have preferred the later sleep pattern because of the influence of older peers in the school. That, however, was not the case. Puberty seemed to be the determining factor. "[The results] gave us the first concrete evidence for trying to look at the biological side,'' says Carskadon, whose research is supported by the National Institute of Mental Health.
To further understand the changes that biology may have on the body's internal clock, Carskadon has been observing boys and girls who are roughly the same age but at different stages of puberty in her sleep laboratory at Butler Hospital, a psychiatric center affiliated with Brown. By having the students follow first their own sleep schedule and then a prescribed one, both at home and in the lab, the researchers try to get the children's body clocks operating on what Carskadon calls "free run.'' That way, the scientists can learn what sleep schedule the young bodies would choose without any of the outside influences of family, school, friends, or cues given by daylight.
In 1994, after hearing a presentation by Carskadon, members of the Minnesota Medical Association wrote a letter to all school superintendents in the state, urging them to push back the beginning of the high school day. It had no apparent effect. According to early findings of a recent survey, not one district has changed its high school start time.
Mark Mahowald, director of the Minnesota Regional Sleep Disorders Center at Hennepin County Medical Center in Minneapolis, points out that many non-educational factors, such as busing schedules and after-school athletics, currently drive schools' schedules. This shouldn't be the case, he says. "If, in fact, schools are set up to educate our children, we've got to change things.''
As for Carskadon, she thinks it makes sense for administrators to reverse traditional school schedules and have elementary students, who are naturally early risers, start the day at 7:30 and push back the start time for high schoolers.
"Certainly some school districts are asking more of many teenagers than they're capable of doing,'' she says. "Sometimes I think they get so caught up in all the other factors. If they stepped back and thought about what they're asking of kids, it wouldn't make much sense to them either.''