["Sleep disturbances are a prominent feature of Huntington's disease (HD) and can substantially impair patients' quality of life. However, sleep complaints and their association with other symptoms and signs of HD have not yet been assessed in large groups of patients or premanifest mutation carriers. Therefore, we aimed to delineate the nature of subjective sleep disturbances and identify important correlates of sleep impairment in HD patients and premanifest mutation carriers.", "Using standardized questionnaires (including Epworth's Sleepiness Scale, Pittsburgh Sleep Quality Index, SCOPA-SLEEP, and Beck's Depression Inventory), daytime sleepiness, night-time sleep, and depressed mood were assessed in 63 HD patients, 21 premanifest mutation carriers and 84 controls.", 'Night-time sleep impairment was significantly more prevalent in HD patients compared with controls (58.1% vs. 34.9%, p = 0.012), but daytime sleepiness was not (12.7% vs. 7.9%, p = 0.560). Depression was the only independent correlate of night-time sleep impairment in HD patients, accounting for 10% of the variance. Compared with controls, both sleep onset latency and wake-up time were significantly delayed in HD patients. Moreover, in HD patients, later wake-up time was significantly associated with cognitive score (r = -0.43), total functional capacity (r = -0.54) and depressive symptoms (r = +0.47). In general, the degree of sleep (phase) changes in premanifest mutation carriers lay in between those of HD patients and controls.'] Do sleep and circadian rhythm alterations correlate with depression and cognitive impairment in Huntington 's disease?