Insomnia is a common sleep problem characterized by difficulty in falling asleep, staying asleep, or enjoying a restful night's sleep. Most sleep experts believe you should get seven to eight hours of sleep a night. This figure varies considerably across the age span and from person to person. Still, if you're getting less than six hours of sleep per night regularly, chances are you're building up your "sleep debt," the cumulative effect of not getting the quantity or quality of sleep that one needs. The Institute of Medicine estimates that between 50 million and 70 million Americans have chronic sleep problems. Studies show that about 30 to 40 percent of American adults experience at least occasional insomnia. About 10 to 15 percent may have chronic insomnia. That means they have trouble sleeping at least three nights a week for a month or more. Insomnia is classified into three categories: Transient (short term): lasting from a single night to a few weeks Intermittent (on and off): episodes occur from time to time Chronic (constant): occurs on most nights and lasts a month or more Insomnia may be caused by many factors, including the following: stress, depression, anxiety, physical illness, menopause, caffeine intake, irregular schedules, circadian rhythm disorders, drugs (including alcohol and nicotine), and occasional or chronic pain. Anxiety and stress are thought to be the most common causes of insomnia. If you're having trouble getting the rest you need, try practicing sensible sleep habits, such as getting up about the same time every day, establishing a presleep ritual to unwind (for instance, taking a warm bath or listening to soothing music), avoiding caffeine six hours before bedtime, and exercising regularly—just not before bedtime. Also, stay away from alcohol two hours before bedtime. Folks mistakenly take a drink to help them fall asleep but awaken hours later as the body breaks down that alcohol. If you've done all you can, however, and still aren't getting good, quality sleep, talk with your doctor. Prescription medications for insomnia are available. But they can cause side effects and are best used only for short periods. If you need additional help, ask for a referral to a sleep specialist. People who suffer from insomnia that lasts for more than a few days should consult a doctor so that the underlying cause can be identified, if possible, and then treated. You may be referred to an overnight sleep study to uncover more clues about your insomnia. If you have loud, irregular snoring, jerking legs, or pauses in breathing in addition to other symptoms of insomnia, you may have sleep apnea, a potentially life-threatening condition. Once the precise cause of your sleep disturbance is identified effective treatment strategies can be initiated to help you get the restorative sleep you need.