Sleep is an essential part of good health. A good night's sleep can help you feel good, look healthy, work effectively and think clearly. But sleep is not always so easy to come by. If you sometimes have trouble falling asleep or staying asleep, you're not alone. A 1991 Gallup study found that more than one-third of all Americans suffer occasional or chronic insomnia. People often are surprised to learn that daytime drowsiness is not an inevitable, harmless byproduct of modern life, but rather a key sign of a sleep problem that could be disastrous if not treated. Recent figures show that nearly a quarter of the population regularly cannot go to, or remain asleep, and every year doctors write out more than 14 million prescriptions for sleeping tablets. The causes of sleeplessness are many and varied. 'It can be due to a medical condition, such as chronic pain from rheumatism or arthritis,' says Professor Jim Horne, who runs the Sleep Research Laboratory at Loughborough University. 'Or it can be chemical, as a result of drinking tea, coffee or alcohol. Chronic or long-term insomnia is often associated with depression or anxiety, and environmental factors certainly contribute.' And sleepless nights, staring wild-eyed into the darkness, are worse than bad dreams, For too many people--an estimated 9percent of the American population--a good night's sleep is an elusive goal. The consequences of fatigue from chronic sleeplessness include accidents in the car and at work, a dramatically increased risk of major depression, and worsening physical illness. Immediate relief is available, in the form of hypnotic agents, for persons who have difficulty in falling or remaining asleep or who cannot obtain restful, restorative slumber. However, long-term improvement usually involves behavioral therapy. These therapeutic approaches must be integrated if the patient's short- and long-term needs are to be addressed.