We sought to estimate the frequency and nature of sleep disturbances in Indian Parkinson's disease (PD) patients. One hundred forty nine consecutive PD patients attending the Movement Disorders Clinic of the All India Institute of Medical Sciences, New Delhi, India and 115 age-matched healthy controls participated. After clinical evaluation, sleep assessment was done using a 23-question, validated sleep questionnaire. Mean age of PD patients and the duration of illness were 58.37 (S.D. 10.45) years and 5.7 (S.D. 3.85) years, respectively. The mean age of the controls was 56.50 (S.D. 11.45) years (P > 0.05). Sleep problems were seen in 63 (42%) PD patients compared to 12% of controls. These were: insomnia in 32%, nightmares in 32%, and excessive day time sleepiness in 15% of PD patients as compared with 5%, 5% and 6%, respectively, in controls (P < 0.025). Presence of nightmares was significantly associated with higher Hoehn and Yahr score (P < 0.002), high unified Parkinson's disease rating scale (UPDRS) Part I score (P < 0.000) and levodopa dose (P < 0.025). Excessive daytime sleepiness correlated with higher Hoehn and Yahr stage (P < 0.004), and levodopa dose (P < 0.040). The sleep latency was longer in PD patients as compared to controls (P < 0.000). Multiple logistic regression analysis showed association of sleep disturbances with UPDRS Part III, Schwab and England score, levodopa dose, rigidity score, and bradykinesia score. Sleep problems are much more common in PD patients compared to controls (P < 0.001), and correlate with increased severity of disease.