The writer Fran Leibowitz once quipped that life is what you do when you can't get to sleep. Indeed, for many of us, getting a good night's sleep is an important but elusive goal. Up to 30% of the general population suffers from insomnia, and half of this group experiences the problem as serious. Up to 90% of older people report some type of sleep problem. And drowsiness at the wheel may account for 30% of fatal driving accidents.
Kinds of Sleep Disorders
Sleep disorders are divided into several types: difficulty falling asleep and/or staying asleep (insomnia), excessive daytime sleepiness (hypersomnia), abnormal timing of sleep-wake cycles (circadian rhythm disorder), and abnormal stages of sleep (parasomnia). Occasional trouble falling or staying asleep is normal and usually due to transient stress. But when insomnia continues for weeks or months, it's important to consider possible causes.
Anxiety and depression account for as much as half of the chronic insomnia cases. Treatment of the underlying problem usually leads to improvement in the patient's sleep. About one-fifth of chronic insomnia cases are so-called primary insomnia. This disorder is usually caused by a combination of stress, poor sleeping habits, and a form of conditioned anxiety in which simply getting into their own beds makes sufferers anxious. These people actually sleep better in laboratories than in their homes!
Three Conditions That Can Disturb Sleep
Unlike those with chronic insomnia, only a small percentage of people with hypersomnia have an underlying psychiatric problem. However, nearly 85% have one of three conditions: sleep apnea, narcolepsy, or myoclonus. Obstructive sleep apnea (OSA) is a breathing disorder, usually caused by partial blockage in the back of the throat. OSA is common in overweight, middle-aged men with high blood pressure, and its hallmark is very loud snoring -- the kind that sometimes wakes the neighbors.
Narcolepsy is characterized by "sleep attacks" during the daytime, and in 75% of cases, by sudden loss of muscle tone. Some narcoleptics also experience strange hallucinations just before falling asleep and muscle paralysis upon awakening. Myoclonus refers to abnormal twitching of the calf muscles during sleep, and accounts for about 10% of hypersomnia cases. Circadian rhythm disorders include the common "jet lag" syndrome, as well as sleeping too late or awakening too early because of irregular shift work -- a common cause of on-the-job accidents.