The association between disease severity and sleep-related problems in patients with Parkinson's disease

Although sleep-related problems are a frequent finding in patients with Parkinson's disease (PD), the aetiology is still unknown. We examined the associations between disease severity, sleep-related problems and social status in 116 PD patients participating in the FAQT Study, a prospective, German cohort study evaluating determinants of quality of life in PD patients. 47.4% of the patients reported sleep onset difficulties, 26.7% sleep interruptions, 14.7% had five or more sleep-related events during the night and 71.6% showed symptoms of increased daytime somnolence. The disease severity was significantly associated with sleep-related events (p = 0.01), the depression score with sleep onset difficulties (p = 0.04), sleep interruptions (p = 0.01) and the levodopa dose (p < 0.01). We conclude that depressive symptoms and increasing levodopa doses in PD patients mainly cause sleep onset difficulties and sleep interruptions, while the severity of motor symptoms contributes to sleep-related events like sleep walking, heavy sweating and nightmares.