Do you toss and turn at night, or have problems falling asleep or staying asleep?  Do you have trouble staying awake and alert during the day?  If so, you may be one of the estimated 50-70 million Americans who have a sleep disorder.  Experts estimate that about one-third of adult Americans will experience some sort of sleep disorder in their life time.  And, while many sleep disorders can be treated, most of them go undiagnosed.

Why we sleep remains something of a mystery.  Dr. Michael Twery, director of the National Center on Sleep Disorders Research at NIH’s National Heart, Lung and Blood Institute, says, “Sleep originates with the timing of our biological clock.  The biological clock operates in almost all of our tissues.”  A particular region of the brain called the suprachiasmatic nucleus, he says, operates as the master biological clock.  It orchestrates what Twery calls a “symphony” of hormones and other changes that prepare our body for sleep.

It’s clear that our body needs this sleep, because of what happens when we don’t get enough of it.

“Too little sleep or not enough restorative sleep can seriously affect the way we think, behave, form memories and perform at work and school,” explains Dr. Merrill Mitler, program director for sleep research at NIH’s National Institute of Neurological Disorders and Stroke.  “A continued lack of sleep also puts us at risk for mood disorders such as depression and can lead to poor concentration and poor judgment, social problems, greater risk of car crashes and increased risk of substance abuse.”

There is also what Twery calls the “unseen side” of inadequate sleep.  Because the timing of sleep is linked to a symphony of chemical reactions throughout the body, Twery explains, it’s also linked to our health in more subtle ways.  “When these chemical reactions become misaligned,” he says, “they can contribute to problems with our metabolism and our cardiovascular system, and can eventually lead to increased risk of disease.”

Twery recounts one set of experiments in which otherwise healthy young adults developed resistance to insulin after a few nights of only 4 hours of sleep.  Insulin is a hormone needed to convert sugar, starches and other food into energy.  When the body can’t use insulin properly, diabetes can develop.  After the researchers allowed the young adults to go back to 8-hour sleep periods, the problem reversed within days.

Other studies have found that people who get less sleep tend to have higher rates of obesity, heart disease, high blood pressure and diabetes.  A great deal of research is now focused on understanding the underlying links between sleep and these health factors.

How much sleep do we need?  Adults usually need at least 7-8 hours of sleep a night to feel fully rested when they are awake.  School-aged children and teens need at least 9 hours.  Children in preschool need between 10 and 12 hours a day, and newborns need 16-18 hours.

Many people unfortunately consider sleep a low priority and try to stay awake as much as they can to do more work, watch some TV or fit other things into their busy days.  But others can’t sleep because of an underlying problem.  In fact, there
are more than 70 different types of sleep disorders.

Diagnosing a particular sleep disorder can be difficult, but Mitler says that new tools are giving scientists a better understanding of sleep and sleep-deprived states.  One key tool is functional imaging, which provides real-time images of brain activity during sleep and the sleep-wake stages to learn which areas of the brain may be involved in sleep disorders.

NIH researchers continue to explore the causes and consequences of sleep problems such as insomnia, chronic sleep deprivation and obstructive sleep apnea (which you can read about in the following story).  Even if all these disorders aren’t fully understood, however, many of them can be treated.

If you frequently experience excessive daytime sleepiness or have problems sleeping, talk to your doctor or a sleep specialist.  Mitler recommends that, before you go, you keep a sleep diary of when you usually go to bed, how long it takes you to fall asleep, when and how many times you wake during the night, and when you wake in the morning.  The diary should also include what you ate that day, drinks you had at night containing caffeine or alcohol, use of medicines, smoking and exercise you’ve done.  The records may show a pattern or give the doctor other clues to better diagnose your condition.