Sleep disturbances are common in extrapyramidal diseases, including not only insomnia but excessive daytime sleepiness and parasomnias. In particular, complaints related to sleep are extremely common among patients affected by Parkinson's disease (PD). The underlying causes may include: patient age, associated illnesses, cognitive impairment, motor dysfunction caused by disease, neurochemical changes related to the disease, drugs, and secondary psychological responses to the disease. The exact prevalence of sleep disorders in PD is difficult to ascertain, due to the heterogeneity of patients as well as to the different criteria and methods used to diagnose and classify sleep disturbances. In this study, we will attempt to review the epidemiological data and to describe the various sleep disorders, which have been identified in extrapyramidal diseases, with particular reference to PD. There are no data available at present as to the role of gender in sleep disturbances. Finally, the benefit of sleep on extrapyramidal diseases will be addressed, taking into account that the above causes may modify the effects of sleep.