General information on idiopathic hypersomnolence and narcolepsy
Idiopathic hypersomnolence and narcolepsy are disorders of sleep–wake regulation that usually appear between adolescence and the age of 30 years. They are characterised by chronic daytime sleepiness, which may lead to sudden uncontrollable sleep attacks. Idiopathic hypersomnolence is more common than narcolepsy. Narcolepsy is associated with disturbed sleep at night and abnormal manifestations of rapid eye movement sleep–like behaviour during waking. Symptoms include cataplexy (sudden loss of muscle tone, usually associated with strong emotion), muscle paralysis on falling asleep or waking (sleep paralysis) and vivid hallucinations (often visual) on falling asleep (hypnagogic) or waking (hypnopompic).
Idiopathic hypersomnolence and narcolepsy are diagnosed on the basis of:
- clinical history
- absence of other sleep disorders (particularly obstructive sleep apnoea) on overnight sleep study
- objective evidence of excessive daytime sleepiness, using a multiple sleep latency test or maintenance of wakefulness test.
Advise patients with severe sleepiness to avoid dangerous activities at home and at work. They should not operate a motor vehicle until sleepiness is adequately managed and they satisfy the Australian standards of fitness to drive1.