Teenagers and Sleep

Teenagers and Sleep

I ran across this fascinating article from PBS. The link is at the bottom if you want more info.

In making “Inside the Teenage Brain,” we seemed to hit a nerve — a parental one — when we began looking into the world of teenagers and how they sleep. The patterns that young teens seemed to be experiencing — an inability to go to sleep at night, followed by profound drowsiness on waking — seemed so pervasive that it should come as no a surprise that what parents were seeing at home had already been corroborated in university sleep labs at Stanford and Brown.

Reseachers had always believed that sleep was governed by what was called the sleep-wake homeostasis, that is: “All other things being equal, … the longer one is awake, the greater the pressure for sleep to occur. … This process accounts for the increased need for sleep after staying awake all night.” [1] It seemed perfectly reasonable that people would want to sleep when they were very tired. But it didn’t account for a number of patterns that were obvious outside the lab: jet travellers woke up at 2 a.m. despite being exhausted after flying from Boston to London, teenagers had trouble falling asleep though they also seemed to be very tired, older people often woke up very early in the morning.

The Biological Clock

What researchers discovered is an internal biological clock, a clock that sometimes acts against the sleep-wake cycle by keeping us alert when we should be feeling tired. Sleep researchers Mary Carskadon, now at Brown University, and Bill Dement at Stanford had seen this biological clock in action when they tested a group of 10-12 year olds at Stanford. Dement, who pioneered sleep research at Stanford, wrote about these experiments: “After centuries of assuming the longer we are awake, the sleepier we will become and the more we will tend to fall asleep, we were confronted by the surprising result that after 12 hours of being awake, the subjects were less sleepy than they had been earlier in the same day, and at the 10 o’clock test, after more than 14 hours of wakefulness had elapsed …they were even less sleepy.” [2]

The researchers found that the biological clock opposed the sleep-wakefulness cycle at certain points of the day and at certain ages. It kept people awake when they were very tired. Just before puberty, that internal clock helped teens stay alert at night when they should have been falling asleep. The researchers called this a “phase-delay.”

Sarah Spinks is an independent director and producer. She was with the Canadian Broadcasting Corporation for seventeen years where her documentaries won many awards. Spinks’ last FRONTLINE documentary, “Making Babies,” reported on state-of-the art infertility treatments.

The biological clock or circadian rhythms (from the Latin words “circa” and “dies,” or “around day”) of smaller children don’t show the same delays. Nothing is opposing their need to sleep in the evening. Until the age of 10, many children wake up fresh and energetic to start the day. In contrast, the biological clock of pre-teens shifts forward, creating a “forbidden” zone for sleep around 9 or 10 p.m. It is propping them up just as they should be feeling sleepy. Later on, in middle-age, the clock appears to shift back, making it hard for parents to stay awake just when their teens are at their most alert.

There are millions of adolescents who feel despondent, get poor marks, are too tired to join school teams all because they are getting too little sleep.
Carskadon discovered other important patterns in adolescent sleep. By studying alertness, she determined that teens, far from needing less sleep, actually needed as much or more sleep than they had gotten as children — nine and a quarter hours. Most teenagers weren’t getting nearly enough — an hour and a half less sleep than they needed to be alert. And the drowsiness wasn’t only in the early morning. Teens had a kind of sleep trough in the mid-afternoon and then perked up at night, even though they hadn’t had a nap.

Carskadon is now exploring the effect of light in setting adolescent sleep patterns, for darkness seems to trigger the release of melatonin, often called the “sleep” hormone. Measuring melatonin also helps researchers define the different circadian rhythms of children, teens, and adults.

Sleep Debt

A great concern of sleep researchers is that teens are so sleep-deprived. Bill Dement speaks about the huge sleep debt that many teens and adults carry around with them every day. With most high schools in the U.S. starting around 7:20 a.m. and with many teens going to bed between 11 and 12 p.m., sleep researchers worry that teenagers are suffering an epidemic that is largely hidden. Since students are often driving to school, to sporting events, and home from late-night parties, this sleep debt holds huge risks. Many high school students know of someone, often a high-achieving kid, who on the drive back from a sporting event or dance simply fell asleep at the wheel. On a less dramatic note, there are literally millions of adolescents who feel despondent, get poor marks, or are too tired to join high-school teams all because they are getting too little sleep. Because of their deep concern about these issues, sleep researchers are pushing for later school start times and are trying to introduce sleep issues into the high school curriculum.

Sleep, Learning, and Memory

The other area of sleep research relevant to teenagers, their parents, and teachers is the effect of sleep on learning and memory. In experiments done at Harvard Medical School and Trent University in Canada, students go through a battery of tests and then sleep various lengths of time to determine how sleep affects learning. What these tests show is that the brain consolidates and practices what is learned during the day after the students (or adults, for that matter) go to sleep. Parents always intuitively knew that sleep helped learning, but few knew that learning actually continues to take place while a person is asleep. That means sleep after a lesson is learned is as important as getting a good night’s rest before a test or exam.

This research is done by giving students a series of tests. The students are trained, for instance, to catch a ball attached by a string to a cone-like cup. As they repeat the skill during the test day, they are able do it faster and more accurately. Let’s say they go from catching a ball 50 percent to 70 percent of the time over a period of half an hour. The students who get a good night’s sleep improve when they are retested. On a retest three days after they have a good night’s sleep, they might catch a ball 85 percent of the time. The other students who got less than six hours sleep either do not improve or actually fall behind.

Some of the tests are more demanding. They are called cognitive procedural tasks and they mimic what a student might learn in physics or math, or in certain sports. They present the student with something new to be learned or require an ability to conceptualize, to form a picture of the task in their minds.