In a national survey conducted among 220 patients with Parkinson's disease (PD), 215 reported experiencing disabilities at night or on waking. The most common problems were inability to turn over or get out of bed and a frequent need to pass urine during the night. For the majority of patients, sleep was disrupted. Despite these difficulties, two-thirds of patients rated sleep quality as acceptable or good. The average duration of sleep was 6.5-7 h but approximately 8% of patients reported less than 5 h sleep per night. Hypnotic or sedative drugs were used by 29% of patients to help them sleep but only 6% took any antiparkinsonian medication during the night. Just over half the patients had told their doctor of nocturnal problems; prescription of hypnotic drugs or changes to antiparkinsonian therapy were the remedies most frequently tried. Problems at night are common in PD and, because of their debilitating effect on performance during the daytime, merit special attention.