Insomnia, which is Latin for "no sleep," is the inability to fall asleep or remain asleep. Insomnia is also used to describe the condition of waking up not feeling restored or refreshed. Insomnia is the most common sleep complaint among Americans. It can be either acute, lasting one to several nights, or chronic, even lasting months to years.

When insomnia persists for longer than a month, it is considered chronic. According to the National Center for Sleep Disorders Research at the National Institutes of Health, about 30-40% of adults say they have some symptoms of insomnia within a given year, and about 10-15 percent of adults say they have chronic insomnia. Sleep specialist Dr. William Dement, Director of the Sleep Disorders Clinic and Laboratory at the Stanford University School of Medicine, explains that people who have trouble sleeping every night without exception for months or years are fairly rare. More often, people experience chronic-intermittent insomnia, which means difficulty sleeping for a few nights, followed by a few nights of adequate sleep before the problem returns.

Insomnia can be a disorder in its own right, but often it is a symptom of some other disease or condition. Half of all those who have experienced insomnia blame the problem on stress and worry. In the case of stress-induced insomnia, the degree to which sleep is disturbed depends on the severity and duration of the stressful situation. Sometimes this may be a disturbing occurrence like loss of a loved one, loss of a job, marital or relationship discord or a tragic occurrence. Anticipation of such things as weddings, vacations, or holidays can also disturb sleep and make it difficult to fall asleep or remain asleep. Insomnia can also occur with jet lag, shift work and other major schedule changes.

If you have difficulty sleeping, it is essential to determine whether an underlying disease or condition is causing the problem. Sometimes insomnia is caused by pain, digestive problems or a sleep disorder. Insomnia may also signal depression or anxiety. Often times, insomnia exacerbates the underlying condition by leaving the patient fatigued and less able to cope and think clearly. For insomnia related to a medical condition or pain, ask your doctor about nighttime pain aids.