Parkinson's disease (PD) is associated with sleep disorders which are attributed mainly to dopamine deficiency, nocturnal akinesia, drug therapy, and cofactors such as age and depression. These disturbances affect the macro- and microstructure of both REM and non-REM sleep and motor, respiratory, and autonomic functions. Excessive daytime sleepiness and the interactions between sleep and daytime motor performance in PD are not yet completely understood. Correct diagnosis and treatment of sleep disorders is essential due to the risk of harm to the patient and others and due to their effect on quality of life for all concerned. As sleep disorders in PD are extremely common (about 70%) and may have severe consequences, a systematic sleep history and specific therapy should be considered integral to treatment in every PD patient.