Night Owl Syndrome in Adolescents: Understanding Normal vs. Abnormal Circadian Rhythms

from Caring For Our Future, Fall 2004

By Carole Kline, MS, RN, CPNP

There is a lot of discussion among school and health professionals about establishing later school start times for high-school students. Sleep researchers working with adolescents have found that students learn better when they are allowed to delay school start times to 9 a.m.

The Denver Public Schools system announced that some high schools would start classes as late as 9 a.m. from the traditional start time of 7:30 a.m. for the 2004-2005 school year. Although part of the reason for delaying class start time is related to the termination of school bus service, this decision also was based on current sleep research, specifically in the area of adolescent sleep patterns.

Researchers have identified several changes in sleep patterns, sleep/wake systems and circadian timing systems associated with puberty (Carskadon, 1999). These developmental changes can have a direct impact on daytime functioning, especially in the early morning. Excessive daytime sleepiness can have a negative impact on the daytime functioning of adolescents, placing them at increased risk for injury and decreasing their ability to learn in school. There can be several causes for daytime sleepiness in adolescents, which include insufficient sleep, depression and stress. Other causes can include obstructive sleep apnea and narcolepsy.

The National Institutes of Health has identified adolescents as a population at high risk for problem sleepiness based on “evidence that the prevalence of problem sleepiness is high and increasing with particularly serious consequences.” (NIH, 1997). Drowsiness or fatigue has been identified as a principal cause in at least 100,000 police-reported traffic crashes each year, killing more than 1,500 Americans and injuring another 71,000, according to the National Highway Traffic Administration (NHTSA, 1994). Young drivers under age 25 are responsible for more than half of these accidents.

Circadian Rhythms and Sleep

Sleep/wake cycles are among the biological functions regulated by an internal biological “clock.” This clock is known as the suprachiasmatic nucleus (SCN) located in the hypothalamus, above the crossing of the optic nerves. The SCN is light-sensitive, controlling the secretion of plasma melatonin from the pineal gland when dark and turning off this hormone when exposed to daylight. Melatonin is a hormone that brings on drowsiness and sleep. Other functions controlled by the SCN include the secretion of certain hormones, minor shifts in blood pressure and body temperature along with other metabolic functions. A normal cycle takes 24 to 25 hours to complete. Circadian rhythms are present at birth, but are not fully developed until 4 to 6 months of age.

At puberty, adolescents undergo changes in their sleep/wake cycles that result in a phase delay, or a tendency toward later sleep and waking times. Studies show that a typical high school student’s natural time to fall asleep is 11 p.m. or later. (Wolfson and Carskadon, 1998) With an average sleep requirement of 8.5 to 9.25 hours each night, it is apparent why a delay in school start times would be beneficial.

Behavioral and Psychosocial Factors Influencing Adolescent Sleep

Recent studies by The National Sleep Foundation (2000) show that children in the U.S. get less than the required amount of sleep. The average adolescent gets 7.5 hours of sleep during the school week, with only 15 percent of adolescents reporting that they get 8.5 hours of sleep or more on school nights. In comparison, most European children get approximately one hour a night more than children in the U.S. European children tend to have more structured sleep routines, and rarely have television sets in the bedroom. In addition, few European businesses are open past 6 p.m. There are many factors contributing to the problem of insufficient sleep in the U.S. These include TV, homework, sports, hobbies, dating, computers, malls and a 24/7 society. Studies show that 43 percent of all children in the U.S. have television sets in their bedrooms, which have been associated with poor sleep. Use of drugs, alcohol and caffeine can further interfere with sleep.

Many adolescents have different sleep/wake schedules during the school week vs. the weekend. Weekends may be the time when they try to “catch up” on lost sleep by sleeping as long as 12 hours. Weekend sleep schedules can vary quite a bit from weekday schedules, with 91 percent of all adolescents reporting that they go to bed later than 11 p.m. on weekends.

Delayed Sleep Phase (‘Night Owl’) Syndrome

Although a shift in sleep/wake cycles is normal for most adolescents, for some, the shift becomes dramatic and can interfere with the ability to function during the day.

Case Study

Tim was a 15-year-old who presented to our sleep clinic with a one-year history of daytime sleepiness, fatigue, depression, failing grades and poor attendance at school. His typical bedtime was 3 a.m. and he usually slept until 1 p.m.

His mother was frustrated with his inability to awaken in time to attend school and was concerned that he might not finish high school. The onset of his symptoms seemed to coincide with the divorce of his parents. Tim was under the care of a mental-health professional and was on several medications for depression, anxiety and insomnia in addition to a stimulant to help maintain daytime alertness.

He denied drug and alcohol abuse, and random drug screening was negative. A polysomnogram (sleep study) followed by a multiple sleep latency test ruled out the possibility of obstructive sleep apnea, periodic limb movement disorder and narcolepsy as possible causes for his daytime symptoms.

Tim was prescribed light-box therapy that consists of exposure to bright light in the mornings upon awakening to help readjust the circadian clock to the desired wake-up time. The first two attempts at initiating therapy were not met with success as Tim was not motivated to initiate therapy and his mother was away on frequent business trips. Eventually, Tim decided that he was motivated to discontinue his medications and wanted to be able to spend more time with his friends instead of sleeping. His decision to try light-box therapy succeeded. He was able to shift his wake-up time to 7:30 a.m. and transferred to an alternative high school with a delayed start time of 9:00 a.m. Tim was able to finish high school with high grades and currently attends college. He is off all his medications and uses his light box occasionally when he feels his sleep/wake cycle starting to shift, which is typically in the winter months when exposure to daylight decreases.

Treatment

Treatment of delayed sleep phase syndrome can be accomplished through the use of light-box therapy. Artificial light in the form of a light box is used to emit 10,000 lux for a period of 30 minutes, with the patient sitting directly in front of the light. Dosage and timing of the exposure is determined by a sleep specialist after reviewing a two-week sleep diary of the patient’s usual sleep/wake cycle. Light boxes commonly have been used for the treatment of seasonal affective disorder, common in areas of the world such as Alaska, where exposure to sunlight is minimal during the winter months. For delayed sleep phase syndrome, early-morning direct exposure to bright light will lead to an earlier wake time and advance sleep onset at night.

The key to treating delayed sleep phase syndrome in adolescents is motivation. The adolescents must take control over their sleep routines and find a meaningful reason for changing. Parents cannot force them to comply or they will be met with even more resistance. In Tim’s case, he wanted to spend more time with his friends, but more important to him was stopping all of his medications, which he felt made him worse. His mother wisely decided to place the light box in his room and allow him to decide when he was ready to give it a try.

Melatonin often is discussed as a treatment for sleep problems; however, this “dietary supplement” has not been approved for use by the FDA and has some worrisome side effects. More research needs to be done on melatonin levels and level of sexual maturation. There is some evidence that this hormone could delay puberty and interfere with normal development.

Conclusion

Adolescents are increasingly at risk for the detrimental effects associated with insufficient sleep, which include injuries and death, low grades and poor school performance, difficulty controlling emotions and behavior problems along with an increased likelihood of stimulant use. It is important to recognize that excessive sleepiness during the day and other sleep problems can be a sign of an underlying disorder. For most adolescents, practicing healthy sleep habits will usually lead to an improvement in symptoms

For a complete list of references, please contact the author.