TO SLEEP, PERCHANCE TO . . .STAY AWAKE?
SLEEP, CIRCADIAN RHYTHMS, AND SLEEP DISORDERS

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Nearly three-fourths of Americans reportedly have at least one symptom of a sleep disorder several times a week, according to the "2002 Sleep in America" poll, conducted by the National Sleep Foundation. Symptoms might include difficulty falling asleep, wakefulness during the night, waking up early and not being able to get back to sleep, waking up unrefreshed, snoring, painful tingling in the legs, or pauses in breathing. That's an estimated 30-40 million Americans who are not getting restful sleep.

Why do we sleep anyway? Though there are many mysteries still surrounding sleep, one thing is clear: Sleep isn't a waste of time. The body repairs and restores nerve cells in the brain while we're sleeping. As we age, we lose our ability to sleep effectively. The reasons aren't entirely known. The phenomenon could be a normal part of aging or it could be related to medical problems common in the elderly.

A century ago, most people lived their lives according to the natural rhythms of the rising and setting sun. Though our bodies are still regulated by these circadian (Latin for "about a day") rhythms, today's technologies and lifestyle can keep us out of phase, disrupting our sleep.

The human body reacts naturally to "zeitgebers" (German for timegiver), environmental cues, most often light, that tells us when it's time to sleep or wake. Shift workers, especially those who work several different shifts in any given period, may have a hard time adjusting to different schedules. Frequent fliers may also have disrupted sleep schedules since the circadian rhythm is slow to adjust to change. By the time the body has caught up with the time zone change, the traveler may be back home. Some people-night owls-naturally get sleepy later, while others, often called larks, are earlier risers. Most people fall somewhere in between.

Generally, there are five phases in a sleep cycle: 1, 2, 3, 4, and REM (rapid eye movement) sleep. Each cycle lasts about 90 to 110 minutes and the cycle is repeated throughout the night, with the most time spent in stages 1, 2, and REM. Disrupted sleep can happen at any point during the cycle or even during non-sleeping hours.
In the Sleep in America poll, up to 93% of respondents agreed that not enough sleep can impair a person's performance at work, 91% agreed that lack of sleep can put a person at risk for injuries, and 90% said that sleep deprivation can lead to health problems. At the same time, in the past century, we have reduced our average time asleep by 20 percent and, in the past 25 years, added a month to our average annual work/commute time. We know we have problems sleeping; we just don't know to solve them.

Sleep disorders fall into several broad categories. Dyssomnias are characterized by insomnia (an inability to stay asleep) or excessive daytime sleepiness. These disorders include apnea (breathing stops or slows during sleeping), narcolepsy (an inability to control when you fall asleep), restless leg syndrome or periodic limb movement, and more typical insomnias. Parasomnias describe abnormal behaviors during sleep, like sleep walking or night terrors. Secondary sleep disorders result from other dysfunctions like psychiatric disorders, neurologic diseases, or reactions to medications. Circadian rhythm disorders, disruptions in the natural sleep cycle, include jet lag, shift work, or out-of-sync sleeping schedules.

If you think you're one of the many Americans who suffers from a sleep disorder, pay attention. You're in for eye-opening evening.

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Mini-Med Faculty

Timothy H. Monk, Ph.D., D.Sc.

Professor of Psychiatry, School of Medicine and Director, Human Chronobiology Program, , Western Psychiatric Institute and Clinic

Daniel J. Buysse, M.D

Associate Professor of Psychiatry, School of Medicine and Medical Director, Sleep Evaluation Center, UPMC Health System

Dr. Buysse earned his B.A. with high distinction in English and biomedical science from the University of Michigan, Ann Arbor, in 1981. He earned his M.D. from Michigan in 1983 and then completed an internship in psychiatry at the University of Pittsburgh, Western Psychiatric Institute and Clinic in 1984. Dr. Buysse has held progressively responsible positions at WPIC since then, completing a residency in 1987, becoming a research fellow in 1987, and earning the title of assistant professor in 1988.

In 1989, Dr. Buysse was named to his current position of medical director of the sleep evaluation clinic. He is also director of the Clinical Neuroscience Research Center at UPMC and co-director of the American Academy of Sleep Medicine's Accredited Sleep Medicine Fellowship at UPMC Health System. His research is focused on insomnia, and is based on three related themes: 1) sleep and circadian rhythms in aging; 2) sleep in depression; and 3) the evaluation, biology, and treatment of primary insomnia.

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