Understanding teenagers' sleeping habits

Main Category: Psychology / Psychiatry
Article Date: 19 Oct 2004 - 12:00 PDT


As any parent of a teenager knows, rousing a sleeping adolescent can be, to put it mildly, difficult. Grumpy and monosyllabic until later in the day, it can be just as much of a struggle to get your teen to go to bed at night, what with homework, instant messaging, email and general late-night wakefulness.

On the weekends, the door to the 'Bat Cave' remains shut until the crack of noon -- or even later -- while everyone else in the family, up for hours, goes about their business.

Should you be concerned about this antisocial rite of passage? Or is there something more to your adolescent's sleep habits?

Relax. There is good news. Landmark studies into the adolescent brain have revealed that the contrariness of a teen's biorhythms are in fact just what nature intended. According to Dr. Jay Giedd, chief of brain imaging at the Child Psychiatry Branch of the National Institute of Mental Health (NIMH) in Bethesda, MD, and colleagues at the University of California at Los Angeles (UCLA) as well as at McGill University in Montreal, daytime sleepiness and late-night alertness are the result of a shift in the sleep/wake cycle as growth hormones kick into high gear. Beginning in 1991, they used magnetic resonance imaging (MRI) to study brain growth in 1,000 children every two years from the age of 3 to 18 years. They found that during the night, growth hormone is released during Rapid Eye Movement (REM) or "dream sleep," which takes place at the end of each sleep cycle. "One of parents' early observations," notes Dr. Roger Tonkin, a Vancouver pediatrician and adolescent health care specialist, "is that the kid who used to jump out of bed now has to be hauled out just to get on school on time."

Importantly, it's not just your teen's shoe size that's getting bigger. His or her brain is also growing. While it has been well documented that 95% of brain development takes place by the age of five years, the NIMH study, which was conducted over a nine-year period, indicates that there is a second wave of brain growth, particularly in the prefrontal cortex or "thinking" part of the brain, which continues into the teen years and even into the 20s.

During this time, new brain cells and neural connections or "wires" which connect the right and left sides of the brain and are critical to intelligence, self-awareness and performance, grow like branches on a tree. Daytime stimulation, in the form of school and social interaction, gets "hard-wired" into the adolescent brain during the latter stages of sleep, including REM sleep.

Cut these sleep stages short and performance suffers the next day, says Dr. Carlysle Smith, professor of psychology at Trent University in Peterborough, Ont. "If you want to learn really well and to be really efficient in your learning, the best way to do it is to get a good night's sleep," he says.

For the past 30 years, Dr. Smith and colleagues have pioneered research into sleep deprivation and performance in people 18-24 years of age. Their studies in young college students 18 to 24 years of age attending Trent University show that when you teach people new tasks and then deprive them of REM sleep, test scores go down. What's more, Dr. Smith suspects this effect, particularly in certain kinds of memory that is sensitive to sleep loss, may be even more dramatic in younger students. "Kids in grade school should be getting 9 or 10 hours a night," he says. "If they're not, they're probably not learning all that well."

Most teens probably need about 9.5 hours of sleep, say experts, but the reality of a typical teen life -- early morning soccer or swim practice, homework and perhaps a part-time job after school -- means that most are lucky to get 7-1/2 hours. Chronic sleep deprivation can affect mood and make it difficult for a teen to perform or even react appropriately.

Since the amount of sleep everyone needs for optimum performance is very individual, how do you tell if your teen is getting enough sleep to live up to his or her learning potential? Dr. Tonkin suggests that while some teens seem to be able to cope with chronic sleep deprivation, others become irritable and apathetic. The treatment? Let him or her sleep whenever they can, including the weekends. If your teen wants to sleep until noon on Saturday, advises Dr. Tonkin, "let him."

However, catching up on sleep on the weekend, while perfectly normal for most teens, may not help learning, warns Dr. Smith. "If you learn something on Tuesday and are short of sleep until Saturday, it's too late," he explains. "You've got to get it the same night."

What is so important about REM sleep

Even those people notorious for tossing and turning all night are absolutely motionless during Rapid Eye Movement (REM) sleep or "dream" sleep. According to sleep researcher Carlysle Smith, professor of psychology at Trent University in Peterborough, Ontario, "There is absolutely no muscle movement possible; you are absolutely paralyzed."

Except, of course, for your eyes. During REM sleep, special electrical activity emanating from the brain stem floods the rest of the brain, causing the eyes to move back and forth under closed eyelids. The more learning that has occurred before you went to sleep, the more intense -- and rapid -- the eye movements during this stage of sleep, Dr. Smith and colleagues have found.

"We looked at students after they had finished an exam versus after they had finished just another day of school," he explains. "After an exam, we saw massive increases in the number of eye movements, which reflect this special brainstem activity."

Most recently, collaboration with researchers in Belgium who are using a PET (Positive Electron Tomography) scan to study brain activity has revealed that if a particular area of the brain is active during the learning of a task when the subject is awake, then it is especially active when the subject goes to sleep, during REM sleep. A coincidence? Dr. Smith thinks not. "We think that the neurons are doing further memory processing in some way," he explains.

This article was written by Kristin Jenkins, a Toronto writer and editor specializing in medicine and health

http://www.canadian-health-network.ca

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