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Sleep disorders 

Sleep disorders

Sleep disorders

Paul J. Reading


July 30, 2015: This chapter has been re-evaluated and remains up-to-date. No changes have been necessary.


Narcolepsy—expanded discussion of possible autoimmune pathogenesis that may result in the destruction of a small subset of hypothalamic neurons containing the neuropeptide hypocretin.

Rapid eye movement sleep behaviour disorder—association with the development of complex forms of Parkinson’s disease.

Updated on 28 Nov 2012. The previous version of this content can be found here.
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date: 29 April 2017

Dysfunctional sleep is an important cause of morbidity. Sleep problems can loosely be divided into insomnias, disorders causing excessive daytime sleepiness, and parasomnias, with some conditions having elements of all three categories.


Chronic insomnia usually has a behavioural or psychological basis and responds best to cognitive or relaxation therapies, although secondary causes of insomnia such as restless legs syndrome may have specific therapies. Circadian rhythm disorders may also present as insomnia, and a number of neurological syndromes such as Parkinson’s disease are also associated with poor quality and fragmented sleep.

Excessive daytime sleepiness

This usually has a specific identifiable cause, with sleep fragmentation or disruption due to sleep disordered breathing being the commonest reason for severe cases (see Chapter 18.5.2). However, at least 2% of excessively sleepy subjects will have a primary sleep disorder such as narcolepsy.

Narcolepsy—a primary disorder of sleep–wake regulation: inability to stay awake for more than a few hours is the most obvious symptom, which may be associated with cataplexy, sleep paralysis and hallucinations (see Chapter 24.5.3)


Non-REM parasomnias—these are very common in children and rarely require investigation or treatment. Sleepwalking, confusional arousals, and night terrors occurring within 90 min of sleep form a spectrum of conditions reflecting abnormal arousals from the deepest stages of sleep. In a few cases the phenomenon persists into adulthood and may require short courses of hypnotic agents or sedative antidepressant therapy to suppress the nocturnal disturbances.

Parasomnias arising from REM sleep—these are most common in middle-aged men and may be a harbinger of a neurodegenerative syndrome such as Parkinson’s disease. REM sleep behaviour disorder occurs when the mechanism to paralyse voluntary muscles during dreams in REM sleep fails, with the subsequent dream enactment sometimes causing significant physical injury. Most patients respond to clonazepam.

Circadian rhythm disorders

Circadian rhythm disorders—these are increasingly recognized. Most arise from jet lag or shift work; a few reflect abnormalities of the intrinsic clock mechanisms, of which delayed sleep phase syndrome is commonest, especially in adolescents, usually presenting with severe difficulties arising from bed for morning activities. Treatments are partially effective and include melatonin taken mid-evening and phototherapy given in the early morning.

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