Teens and Sleep

Nearly every parent with teenagers has heard these comments or similar ones. Nearly every teenager has made these or similar comments to their parents. Middle school, high school, and college teachers note that many of their students are sleepy and some students actually sleep in class. These students typically have academic difficulties as they progress in school. Yet, most educators also note that many of these same students seem to wake up and get a "second wind" in the afternoon, often about the time that the school day is ending.

Why do teenagers have difficulty falling asleep on school nights and then difficulty awakening on school day mornings? Why are so many teenagers sleepy in morning classes? Is it because teenagers are asserting their independence or rebelling against authority? Is it because teenagers are just plain obstinate? Or are their other reasons why many teenagers have difficulty falling asleep at a "reasonable" hour and awakening early enough to get to school on time? Sleep problems are common in teenagers and scientists have learned that powerful biologic forces underlie their sleep/wake characteristics.

We now know that our need for sleep is not constant throughout life. We know that newborns sleep the majority of the time, day and night. Between 3 and 6 months of age, infants obtain most of their sleep at night supplemented by daytime naps. By age one, most youngsters require 14 hours of sleep, the majority of which occurs at night supplemented by 2 daytime naps of 1 to 3 hours. By the age of 2, most children take only 1 nap and between the ages of 3 and 8 napping is generally discontinued. Five year old children typically require 11 hours of sleep per 24 hours. Between the ages of 9 and 10, children typically are able to maintain excellent daytime alertness with 9 to 10 hours of sleep per night. What happens to teenagers?

Researchers at Stanford University in the late 1970’s did a series of sleep experiments on children attending the Stanford Summer Sleep Camp. Preadolescent children attended this annual summer camp for consecutive years as they matured through their teens. After allowing the 9 and 10 year old children to sleep for 8 hours a night, the children were then asked to lie down and attempt to sleep every 2 hours during the daytime. The children were monitored to determine how long on each nap it took them to fall asleep. For each nap, the children were given 20 minutes to fall asleep. With 8 hours of sleep a night, the 9 and 10 year old children were unable to fall asleep within 20 minutes on any of the naps (usually 5 or 6 naps during the day). Thus, 9 and 10 year old children when given 8 hours of sleep a night are not sleepy during the daytime.

A very interesting observation was made, however, when these same children were studied as teenagers. Teenage children, when given 8 hours of sleep per night fell asleep in less than 10 minutes on all naps! When teenagers were allowed only 6 hours of sleep a night (the average teenager gets about 6 to 7 hours of sleep per night), they fell asleep in less than 2 minutes during the daytime on all naps! Thus, teenagers with a full 8 hours of sleep per night demonstrate significant sleepiness in the daytime. Teenagers allowed only 6 hours of sleep per night demonstrated severe sleepiness; in fact teenagers given 6 hours of sleep a night were as sleepy as untreated patients with narcolepsy, a disease characterized by severe sleepiness requiring multiple naps and stimulant medications to treat. This level of sleepiness is associated with severe dysfunction in the daytime which includes falling asleep during boring activities (attending classes, sitting and reading, driving) and difficulty with memory retention. However, when these same teenagers were required to sleep 10 hours per night, they did not fall asleep during the daytime naps.

These findings were unexpected and very surprising. Teenagers require more sleep, by 1 to 2 hours, than do their younger 9 and 10 year old siblings, yet most teenagers get 1 to 2 hours less. Teenagers are the sleepiest members of society and this sleepiness is associated with poor school performance, increased drug and alcohol use, and increased automobile accidents. This level of sleepiness may also play a role in the high rate of teenage suicides.

However, in addition to requiring more sleep than do 9 and 10 year old children, or adults, teenagers typically have altered biologic rhythms which vary the time of night teenagers sleep best and the times of day teenagers are most alert. The timing of sleep and wake is very dependent on the sun. Humans typically sleep at night and are awake in the daytime. Probably the main determinant of when humans sleep is the "biologic clock", a group of 10,000 cells located deep within the brain in the hypothalamus. The cells of the biologic clock act independently of when we are awake and when we are asleep but are very responsive to bright light. The "biologic clock" cells switch the brain to the "wake" state for about 16 hours or so a day and switch the brain to the "sleep" state for about 8 hours or so a day (in the adult human). Thus, when the "biologic clock" is "on", the tendency is for humans to be awake. Conversely, when the cells of the "biologic clock" are "off", the tendency is for humans to sleep.

It is very difficult to obtain restful, consolidated sleep when the "biologic clock" is turned "on". Sleep when the "biologic clock" is turned "on" is characterized by difficulty falling asleep and frequent awakenings if sleep occurs. Everyone has experienced difficulty sleeping during the day after having been awake all night. Conversely, it is difficult to maintain optimal alertness when one tries to stay awake when the "biologic clock" is turned "off". Wake when the "biologic clock" is "off" is characterized by difficulty concentrating, difficulty staying on task, and difficulty remaining awake unless stimulated. Everyone has experienced difficulty staying awake all night, for instance.

Most sleep specialists feel that it is the biology of the brain that requires sleep. Thus, as a person is awake all day, that person develops a need for sleep. The "biologic clock" stimulates the brain to stay awake in the face of the sleep debt that accumulates during the daytime. The activity of the "biologic clock" allows humans to remain awake for 16 hours at a time and thereby postponing sleep until night-time. When the "biologic clock" turns off the stimulus to stay awake is lost and the sleep debt built up during the day gets paid off during sleep. Humans then obtain consolidated sleep until the biologic clock turns on the next day when the process starts over.

The actions of the "biologic clock" are independent of the need for sleep. In humans, bright light (such as sunlight) is the best zeitgeber (time-giver, clock setter). Appropriately timed bright light (10,000 lux for 45 minutes) can reset the biologic clock by as much as two hours. Ten-thousand lux of light is about the amount of light in Walla Walla one hour after sunrise in the middle of the summer. Light acts to activate the biologic clock, and thus one should get light during desired wake hours and avoid light during desired sleep time. To get up earlier, watch the sun rise. To go to bed later, watch the sun set. However, the timing of the biologic clock (and thus one's sleep/wake cycle) can be changed no more that two to three hours per day.

Often teenagers have difficulty falling asleep in the evening and difficulty awakening in the morning. There are at least two major reasons for this sleep pattern. It is commonly assumed that teenagers require less sleep than do their younger siblings when in fact teenagers require more sleep. Because of this, teenagers are frequently sleep deprived. To make matters even worse, teenagers typically don’t get appropriately timed bright light as the following example illustrates.

When Michael was 10 years old, he went to bed at 9 pm and awakened promptly at 6:30 am to get ready for school. Michael did well in school and was a very responsible young man. Thus when he entered high school, his parents, thinking that he was now nearly an adult, allowed him to stay up until 10 pm on school nights and midnight on weekends. On Saturdays and Sundays he was allowed to sleep in and he usually awakened between 10 am and noon when he went outside (in the bright sunlight) to do his chores. By Sunday night, he was unable to get to sleep at 10 pm and although he went to bed then he typically didn’t fall asleep until midnight. It was very hard for him to get out of bed at 6 am for school and he was often late. In the winter time he went to school in the dark. While in school, the rooms had only 200 to 400 lux of light. He went home after school at 1:30 pm in the bright mid-day light.

This is a typical pattern for teenagers. During the weekdays, they are sleep deprived (bedtime 10 pm, wake time 6 am; 8 hours sleep but they need 9 or 10). On weekends, they typically are allowed to stay up until 11 pm or midnight and they are typically allowed to "sleep in" on Saturdays and sometimes on Sundays. They sleep longer in an attempt to pay off the accumulated sleep debt. The first bright light occurs often at around noontime, telling the "biologic clock" that noon is when the day starts. If the "biologic clock" is set to start the day at noon, it will end the day 9 to 10 hours earlier (often between 1 and 3 am). Thus on Sunday night, when the teenager tries to go to sleep at 10 pm, he is unsuccessful because his "biologic clock" is still "on." He also finds it nearly impossible to awaken at 6 am because his "biologic clock" is still "off."

How does one prevent this from happening and how does one treat this when it does happen? It is very important to remember that to function optimally, teenagers typically require 9 to 10 hours of sleep every 24 hours. It is also important to remember that the biologic clock needs to be reset daily by bright light because it typically runs a 24.5 to 25 hour day. Thus, teenagers (and adults with this problem) should try to awaken at approximately the same time (give or take an hour or so) every day, including weekends. The importance of awakening at about the same time every day cannot be overstated! Immediately after awakening, 30 to 40 minutes of bright light will appropriately reset the "biologic clock". During winter time, some people have to use commercially available light boxes for this purpose. If a teenager awakens at approximately the same time every day (weekends included) and gets bright light upon awakening, bedtime will not be a problem. The "biologic clock" will turn "off" approximately 9-10 hours (8 hours in adults) before it turns on. Thus going to bed at a "reasonable" time will be easy if one consistently awakens and gets bright light at the same time every day.

By following the simple practices of awakening at about the same time (give or take 1 to 2 hours) daily and getting bright light and by remembering that the need for sleep increases during the teenage years, teenagers can sleep well. If teenagers sleep well at night, they are very likely to function well in the daytime.