Sleep and neurodegenerative diseases.

Sleep disturbances are common in neurodegenerative diseases. Disturbed sleep can result in fatigue, irritability, morning headaches, impaired motor and cognitive skills, depression, and daytime somnolence. The major sleep complaints include: insomnia, hypersomnia, parasomnia, excessive nocturnal motor activity, circadian sleep-wake rhythm disturbance, and respiratory dysrhythmia. The pathogenetic mechanisms of sleep disturbances may be secondary to direct structural alteration of the sleep-wake generating neurons or from several other indirect mechanisms. At the biochemical level, neurodegenerative diseases may be largely classified as tauopathies, alpha-synucleinopathies, and other diseases. Overnight polysomnography (PSG) and multiple sleep latency test are the two most important diagnostic laboratory tests in the evaluation of sleep disturbances. Management of sleep disturbances is complex and is based primarily on the nature of the sleep disturbance. The clinical profiles, pathogenetic mechanisms, PSG findings, and management issues are discussed here with reference to some common neurodegenerative diseases.