Abstract

Altered sleep and vigilance are among the most frequent symptoms, besides parkinsonism, in movement disorders. As many as 60% of patients with Parkinson's disease (PD) experience insomnia, 15-59% show rapid eye movement (REM) sleep behavior disorders (RBDs), and 30% show excessive daytime sleepiness. Insomnia is a distressing difficulty to maintain sleep, which is exacerbated by motor disability, painful dystonia, restless legs, dysuria, anxiety and depressed mood. Improving night-time motor control by overnight treatment with levodopa, transdermal or long-acting dopamine agonists, or bilateral subthalamus stimulation, can improve sleep continuity. RBDs are violent, enacted dreams that expose the patient or their sleeping partner to night-time injuries. A striking improvement of parkinsonism is observed during these behaviors in PD. RBDs are thought to be caused by lesions in the REM sleep atonia system, and can, in association with other early markers of neurodegenerative diseases, such as olfactory, cognitive and autonomic disturbances, precede parkinsonism by several years. Daytime sleepiness, often with a narcolepsy-like phenotype, is a common occurrence in PD, owing to lesions in the arousal systems of the brain. The use of dopamine agonists increases the risk of sleep attacks, especially when driving, suggesting a drug-disease interaction.