Sleep disorders occur in 74-98% of patients with idiopathic Parkinson's disease (PD), adversely affecting their quality of life. Sleep disruption takes the form of sleep fragmentation with frequent and prolonged awakenings and daytime sleepiness. Nocturia, difficulty in turning over in bed, painful leg cramps, vivid dreams/nightmares, back pain, limb/facial dystonia and leg jerks are the main causes of nocturnal awakening in PD patients. Sleep disturbance gradually worsens with disease progression, suggesting that it is related to the severity of the disease. Sleep disturbances may be generally considered as part of the normal aging process, being more common in the elderly. However, no significant associations between sleep disturbances and either age or disease duration was found in a survey of 100 PD patients. Disturbed sleep maintenance in PD patients was more severe than in age-matched controls, and nocturnal awakening was frequently caused by nocturia, pain, stiffness and difficulty in turning over in bed. Sleep disturbance is also a complication of chronic levodopa therapy. Recent data suggest that controlled-release levodopa is less likely to cause nocturnal symptoms than standard levodopa, particularly in mild-to-moderate disease. Depression, which is common in PD patients, contributes to sleep disturbance but has a lesser influence than the disease process itself. Hypnotic and sedative agents, as well as anti-depressants if required, are useful in ameliorating sleep disturbances in PD patients; intranasal desmopressin appears to be effective in reducing nocturia.