logo Sleep disorders

Sleep disorders can be either primary or secondary. Primary sleep disorders are not caused by another disorder (psychological or medical) or by use of a substance (such as medication or some other drug). Secondary sleep disorders occur in association with another medical or psychological disorder, or use of a substance, which is considered to be the cause of the sleep problem. Sleep disorders are divided into four categories and each category covers a number of specific disorders.

In order to be considered a disorder the problem must occur repeatedly and either cause distress or decrease the normal level of functioning.

A summary of the more common or severe disorders is presented in the table below. For detailed information, please refer to the ICSD-2001, or a sleep specialist. The References list on this site provides contact details for some other sources of information or assistance.

Primary sleep disorders


Dyssomnias Disorders that are experienced as difficulty initiating or maintaining sleep, or excessive daytime sleepiness.
Insomnia Difficulty initiating or maintaining sleep, or non-refreshing sleep, persisting for a period of at least one month. Effects on mood and performance are often noted. The difficulties are not related to another disorder, substance or medication.
Breathing-related sleep disorder Disruption of normal sleep caused by abnormal breathing during sleep, leading to excessive daytime sleepiness. The disorder is usually marked by loud snoring, or pauses in breathing followed by choking or fighting for breath (termed apnoea).
Narcolepsy Extreme sleepiness associated with repeated, irresistible and involuntary sleep attacks occurring daily over at least three months. Symptoms sometimes include episodes of sudden muscle weakness in response to strong emotion (cataplexy), or disturbances of the transition between sleep and wakefulness.
Restless legs syndrome Uncomfortable sensations in the limbs producing a strong impulse to move them in order to gain temporary relief. May interfere with sleep initiation or maintenance, causing daytime fatigue or sleepiness.
Periodic limb movements disorder Brief, repetitive jerking of the limbs (particularly legs) beginning at sleep onset, occurring at 20-60 second intervals through the night, but decreasing during slow-wave and REM sleep. Lead to complaints of insomnia or excessive daytime sleepiness.
Circadian rhythm sleep disorders A persistent or recurrent pattern of sleep which is not aligned with lifestyle demands and social expectations. Can be related to stage of life, inter-time-zone travel (jet-lag) or shift work.
Parasomnias Behavioural or experiential events which occur during sleep. Complaints are usually of the experience of these events, rather than of insomnia or excessive daytime sleepiness.
Nightmares Regular occurrence of distressing dreams, which cause awakening and remain in memory at the time of waking.
Sleep terrors Repeated incidents of arousal from sleep with behaviour suggesting intense fear or distress. The individual is difficult to awaken and usually has no memory of dreaming if awoken. The following morning, the individual has minimal or no recollection of the event.
Sleepwalking Arousal during sleep, ranging from sitting up in bed to walking about and performing activities. Usually difficult to awaken and little or no recall the following morning.


^ Top of page ^


Secondary sleep disorders


Sleep disorders associated with mental, neurologic, or other medical disorders Disorders which occur in association with another medical, neurological or psychological disorder which is considered to cause the sleep problem.
Prominent sleep-related symptoms for at least one month The symptoms of these disorders may be identical to those experienced in insomnia (including hypersomnia: excessively long but unrefreshing sleep periods), any of the parasomnias, or a mixture of symptoms, occurring in association with another disorder.
Substance-induced sleep disorders This category is for disorders that are caused by concurrent use, or recent discontinuation of use of a substance, including medication.
Prominent sleep-related symptoms The symptoms of these disorders may be identical to those experienced in insomnia (including hypersomnia: excessively long but unrefreshing sleep periods), any of the parasomnias, or a mixture of symptoms, directly caused by exposure to a drug of abuse, a toxin or medication.

^ Top of page ^


logo Prevalence of Sleep Disorders

Population survey data indicate a prevalence of insomnia in the adult population of 30% to 45% in any one year (DSM-IV-TR). Chronic or long-term insomnia is believed to affect 9% to 12% of adults ( Morin, Hauri, Espie, Spielman, Buysse & Bootzin, 1999).

Breathing-related sleep disorder is another disorder which is relatively common, with a prevalence estimated to be between 1% and 10% of the adult population. Circadian rhythm disorder has an estimated prevalence of up to 4% in adults and 7% in adolescents. Up to 60% of shift workers may exhibit the “shift-work type” of circadian rhythm disorder. Prevalence has not been well established for most sleep disorders and prevalence of other disorders is generally estimated to be lower than those already mentioned. Whilst nightmares and sleep walking are quite common experiences, they do not usually occur with sufficient regularity or severity to be considered to be a disorder. (DSM-IV-TR).

^ Top of page ^


logo Treatment of Sleep Disorders

Generally, sleep disorders are treated with medication, education and/ or a mechanical device for breathing-related disorders (e.g. continuous positive airway pressure [CPAP] pump for obstructive apnoea). Other forms of treatment are available, including alternative remedies, hypnotherapy, traditional Chinese medicine and acupuncture.

^ Top of page ^


Copyright © 2024 Sleep Therapy Australia
Permission is granted for reproduction of this page for personal use.

Site by Don O'Connor