With the beginning of puberty, most young people go from being well rested to being chronically sleep-deprived. Most teenagers simply don't sleep enough. Homework, TV, friends, extracurricular activities, and telephone conversations steadily push bedtime further and further back. Some studies of teens who also have a part-time job show that teenagers who work more than 20 hours a week experience very high levels of daytime sleepiness.

It's not just that teens don't set aside enough time for sleep. Their bodies tell them to stay up late. Beginning with puberty and continuing into their twenties, their sleep-wake cycle lengthens to 25 or 26 hours, which is why most teenagers are liveliest in the evening, stay up late and sleep late the next day. The absentee rates of university students for the first class of the morning have reached 40 per cent. Some education administrators have considered accommodating this circadian shift by changing the hours of high school and university so that the school day starts later and ends later.

Benefits of sleep
When your teen does get adequate sleep, he's more cheerful, more alert, less susceptible to colds and flu, and also less accident-prone. If your son is learning to drive and is obviously dead tired, you're well within your rights to hold on to the car keys. The immediate effects of sleep deprivation are poor concentration and judgment. Some researchers go as far as to suggest that some of the impulsive and irresponsible behaviour associated with "the crazy teens" may simply be a consequence of inadequate sleep.

Teens need to learn that sleep is not wasted time. Virtually all dreaming that a person remembers occurs in the rapid eye movement (REM) segment of sleep. Dreaming may be one part of sleep that your teen appreciates, because many teen dreams are sex dreams. REM sleep is important for other reasons. Without adequate REM sleep, a person car't concentrate, makes frequent mistakes, and is more prone to depression. Your teen needs adequate REM sleep to remember for longer than a few days what she has been studying.

Your teen has probably discovered that cramming for exams actually works. She can memorize chemistry formulas at 2:00 a.m. and spew them out on an exam paper later that morning. But she may not realize that if she doesn't get adequate REM sleep, the formulas won't move on from her short-term memory to her long-term memory. That's why she flounders in chemistry class the following term.

How Much Is Enough?
As with adults, individual sleep needs vary. You'll know your teen is getting enough sleep if he awakens refreshed. But if he has to set three alarms to wake up in the morning, he's definitely not catching enough ZZZ's. The Canadian Sleep Society's recommendation is that teens should sleep one hour more of each twenty-four hours than they did in their preteen years. Their rapid body growth during adolescence requires between 9 and I I hours of shuteye. To achieve this amount of sleep, your teen's bedtime should be somewhere between 8:30 and 10:30 p.m. If that fact surprises you, it confirms how deeply sleep deprivation is ingrained in our society, as Vancouver psychologist Stanley Coren points out in his book, Sleep Thieves (Free Press Paperbacks, 1997).

During adolescence, a teen must gradually take control of his own bedtime. For a young teen, emphasize that sleep is not a disposable commodity. Reach an agreement that the Tv, computer, and CD player will be turned off at a set time; and restrict phone calls after that set hour. Although he may grumble at the restrictions, he may feel relieved, even grateful, that you're helping him get adequate rest.

Several surveys of teenagers have found that more than half wish they had more time to sleep. Try to help your teens assess their time commitments. Listen attentively, but help them make the connection between lack of sleep and poor grades, between staying up all night and succumbing to a flu virus, between fatigue and too many commitments.

Set a good example
If your teen is a persistent night owl, take a look at your own sleep habits. Adolescents often fail at doing what we tell them, but always excel at imitating what we do. If you want your teen to go to bed at a reasonable hour, you need a bedtime that's not dictated by your workload or the TV listings. If you have the habit of staying up late to meet a pressing deadline, your teen is more likely to stay up past midnight to finish an assignment. If you stay up late to watch an old movie on TV, guess who'll be on the couch beside you?

In our fast-paced society, going without sleep in order to achieve goals is often considered admirable. The executive assistant who works until midnight to prepare the minutes for the board meeting is rewarded with a bonus. The person who not only holds a full-time job but also obtains a diploma or degree through evening classes is admired. Make sure you don't inadvertently reward your child for staying up late by praising the subsequent achievements.

Sleep Problems
Adolescents have to cope with significant new conflicts and anxieties, which may affect their sleep. They might have more nightmares, a sleepless night, or occasional trouble falling asleep. However, a change in sleeping patterns can be a tip-off that something's not right. Adolescents going through depression typically sleep too much. They sleep deeply all night, take naps, or even spend the whole day in bed. They withdraw into sleep as a way of avoiding the problems that they find impossible to solve. If your child sleeps excessively or has problems with sleep, discuss them with your family doctor.

The organization Sleep/Wake Disorders Canada provides informative publications and information on selfhelp groups. Among the descriptions of over eighty disorders of sleeping and waking, you may find background information and suggestions that help you understand what's happening with your child and the avenues you can explore with your doctor.

Delayed sleep phase syndrome
If your teen complains that he can't fall asleep until 3 or 4 a.m. and can't get up for school in the morning, chances are that his sleep phase cycle has shifted. The remedy for this sleep disorder may actually be to go to bed later. Yes, later. Since a teen's natural circadian rhythm sends him to bed later, this approach, recommended by the Canadian Sleep Society, works to correct the phase shift. Your teen should move his bedtime forward three hours each night until he has moved entirely around the clock and reached the desired bedtime. The process takes a week to work. Once he has reached the ideal bedtime, he must maintain both bedtime and wake-up time even on weekends or he will knock the cycle quickly out of phase again.

Or he can try the "weekend crash treatment." Beginning on Friday, he doesn't sleep at all, day or night. On Saturday, he goes to bed around midnight. Then on Sunday morning, he should get up at the time he needs to wake for school. On Sunday night, his bedtime should be 9 or 10 p.m. By Monday, he will have achieved his goal of being awake during the day and able to sleep at night. These regimes are severe, so your teen has to be motivated to get back into sync with the rest of the world. If he wants to give either approach a try, help him out by waking him at the appropriate times.

Night terrors
Night terrors usually occur within an hour or two of falling asleep. A younger child experiencing a night terror (or partial waking, as it's sometimes called) typically sits up, opens his eyes, and grinds his teeth. After a few minutes he lies back down and returns to sleep. But in adolescence, night terrors can be much more dramatic and frightening.

For a teen, a night terror might start with a bloodcurdling scream. Then she may jump out of bed, knock furniture over, even break a window or lamp. During a night terror, your teen risks physical injury. Don't try to restrain her or you, too, will risk injury. Instead, block her access to the stairway and other areas where she might hurt herself. Turn on the light in the hall. Push aside the clutter that covers her bedroom floor. Make a safe place for her to calm down.

One or two episodes of night terrors per year are nothing to be concemed about. But one or two night terrors a month may be cause for concern. The adolescent who guards her feelings during the day is the typical victim of night terrors. Perhaps she's unable, or too frightened, to express her anger about a move, a death in the family, or her difficulties at school. Arrange counselling to help her deal with the emotional blocks that bring on frequent night terrors.

Excerpted from Understanding Your Teen: Ages 13 to 19 by Christine Langlois. Copyright 1999 by Telemedia Communications Inc. Excerpted, with permission by Ballantine Books. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.