Parkinson's disease (PD) is traditionally characterized by a combination of the cardinal motor symptoms of bradykinesia, rigidity, tremor-at-rest, and loss of postural reflex. However, several recent studies have emphasized frequency and serious impact on quality of life by various non-motor symptoms including cognitive abnormalities, mood disorders, autonomic dysfunctions, impaired olfaction, pain, and sleep disorders. Sleep disorders are being increasingly recognized as main non-motor symptom of PD. Sleep disorders, which include the excessive daytime drowsiness, sleep attack, sleep fragmentation, restless legs syndrome, nightmare, and rapid eye movement sleep behavioral disorder are complained by the many of PD patients. Clinical feature, pathophysiology, evaluation tool, and treatment option of sleep disorders are discussed in this review.