Sleep disorders are chronic disturbances in the quantity or quality of sleep that interfere with a person's ability to function normally.
An estimated 15% of Americans have chronic sleep problems, while about 10% have occasional trouble sleeping. Sleep disorders are listed among the clinical syndromes in Axis I of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders , also known as the DSM . They may be either primary (unrelated to any other disorder—medical or psychological) or secondary (the result of physical illness, psychological disorders, or drug or alcohol use).
In the revised fourth edition of the DSM ( DSM-IV-TR ), the primary sleep disorders are categorized as either dyssomnias or parasomnias. Dyssomnias pertain to the amount, quality, or timing of sleep, whereas parasomnias pertain to abnormal behavioral or physiological events that occur while sleeping. Dyssomnias include:
- Primary insomnia—difficulty getting to sleep or staying asleep. Sleep loss is so severe that it interferes with daytime functioning and well-being. Three types of insomnia have been identified (although a single person can have more than one): sleep-onset insomnia (difficulty falling asleep); sleep-maintenance insomnia (difficulty staying asleep); and terminal insomnia (waking early and not being able to go back to sleep). While insomnia can occur at any stage of life, it becomes increasingly common as people get older.
- Primary hypersomnia —excessive sleepiness either at night or during the day.
- Narcolepsy —sudden attacks of REM sleep during waking hours. Many narcoleptics experience additional symptoms including cataplexy (a sudden loss of muscle tone while in a conscious state), hallucinations and other unusual perceptual phenomena, and sleep paralysis, an inability to move for several minutes upon awakening. The disorder is caused by a physiological brain dysfunction that can be inherited or develop after trauma to the brain from disease or injury.
- Breathing-related sleep disorder —abnormalities in breathing cause sleep disruptions. Sleep apnea consists of disrupted breathing which wakens a person repeatedly during the night. Though unaware of the problem while it is occurring, people with sleep apnea are unable to get a good night's sleep and feel tired and sleepy during the day. The condition is generally caused either by a physical obstruction of the upper airway or an impairment of the brain's respiration control centers.
- Circadian rhythm sleep disorder —environmental disruptions to an individual's internal 24-hour-clock affect his or her sleep patterns. This disorder has four subtypes: delayed sleep phase type, jet lag type, shift work type, and unspecified type.
- Nightmare disorder —nightmares repeatedly awaken the affected individual.
- Sleep terror disorder —affected individual is repeatedly awakened from sleep and remains awake and frightened for a short period of time (about 10 minutes or so, usually less), and during that time, the individual is difficult to awaken or comfort. No dream is recalled, and the person often does not remember the event the following day.
- Sleepwalking disorder —repeated episodes of motor activity during sleep, including getting out of bed and walking around.
Other features of parasomnias not listed in the DSM-IV-TR include bruxism (teeth grinding) and enuresis (bed-wetting). Both are often stress-related, although enuresis may also be caused by genitourinary disorders, neurological disturbances, or toilet training problems. A parasomnia only identified in the late twenieth century is REM sleep behavior disorder. Those affected by this condition—usually middle-aged or older men—engage in vigorous and bizarre physical activities during REM sleep in response to dreams, which are generally of a violent, intense nature. As their actions may injure themselves or their sleeping partners, this disorder, thought to be neurological in nature, has been treated with hypnosis and medications, including clonazepam and carbamazepine .
American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. Fourth edition, text revised. Washington DC: American Psychiatric Association, 2000.
Buchman, Dian Duncin. The Complete Guide to Natural Sleep. Collingdale: DIANE Publishing Company, 1999.
Mottolova, Jamin K. Sleep-deficiency, Deprivations, Disturbances and Disorders: Index of New Information and Guide-Book for Consumers, Reference and Research. Washington DC: Annandale, 2002.
Reite, Martin, John Ruddy, and Kim Nagel. Concise Guide to Evaluation and Management of Sleep Disorders. Washington DC: American Psychiatric Publishing Group, Inc., 2002.
The American Academy of Sleep Medicine (formerly the American Sleep Disorders Association), and the Sleep Medicine Education and Research Foundation. 6301 Bandel Road, Suite 101, Rochester, MN 55901. Telephone: (507) 287-6006. Web site: <http://www.aasmnet.org> .