Patients with Parkinson's disease frequently report sleep disturbances which include difficulty initiating or maintaining sleep, parasomnias or excessive daytime sleepiness. The underlying causes include: normal aging, motor symptoms of the disease, antiparkinson drugs, comorbid psychiatric conditions, and concurrent illnesses. An accurate history from the patient and care-giver regarding previous sleep patterns and how they have changed, and the degree of impact these sleep disturbances have on patient's daily life is crucial for successful management. Apart from drug therapy, appropriate counselling and nonpharmacologic treatments have major roles in the overall management. This review summarizes the current concepts of (i) the pattern and function of normal sleep, and (ii) the nature, pathogenesis and management of sleep disturbances in Parkinson's disease.