There is a broad spectrum of sleep disturbances observed in Parkinson's disease (PD). The prevalence of symptoms of insomnia and chronic inability to sleep and their association with other sleep disorders were studied. Altogether 1447 randomly selected Parkinson patients, aged 43-89 years, participated in a questionnaire study. A structured questionnaire with 207 items was based on the Basic Nordic Sleep questionnaire. Questions on demographics, PD, REM Sleep Behavior Disorder, and other issues were included. The response rate was 59 % (N = 854), and of these 81 % returned fully answered questionnaire (N = 689). Prevalence of chronic inability to sleep was 36.9 % (95 % CI 33.3-40.5). Difficulty of initiating sleep was 18.0 % (95 % CI 15.1-20.9), disrupted sleep 81.54 % (78.5-84.4), awakenings during night 31.3 % (27.8-34.8), early morning awakenings 40.4 % (36.8-44.1) and non-restorative sleep 38.5 % (34.8-42.1). In the logistic regression models, poor quality of life and restless legs syndrome correlated significantly with chronic insomnia disorder. Disrupted sleep and early morning awakenings were the most common insomnia symptoms. PD patients do not seem to have difficulties in sleep initiation. Insomnia symptoms including disruptive sleep and non-restorative sleep are common in patients with Parkinson's disease. Inability to sleep is more common as comorbidity than a single sleep problem.
Keywords: Chronic insomnia; Parkinson’s disease; Quality of life; Restless legs syndrome; Sleep disorders.