Changes in sleep characteristics in Parkinson’s disease: a prospective 5-year follow-up study

PURPOSE: Sleep disturbances are common and disabling symptoms in Parkinson's disease (PD). Evolution of sleep disturbances in PD remains incompletely characterized. We aimed to describe changes in sleep parameters and sleep disorders over 5 years in a prospective PD cohort. METHODS: A structured sleep questionnaire was administered to members of the Finnish Parkinson's Association at baseline and at 5-year follow-up. Longitudinal changes were analyzed in 183 participants with complete data at both time. RESULTS: Daytime sleepiness increased significantly, with the proportion of participants with Epworth Sleepiness Scale (ESS) > 10 rising from 30.6% to 38.8% (P = 0.026) and daily napping from 21.4% to 31.7% (P = 0.004). Sleep talking (≥ 1/week) increased from 17.4% to 30.4% (P < 0.001), nightmares from 14.8% to 24.6% (P = 0.003), and mean, REM Sleep Behavior Disorder Screening Questionnaire score (RBDSQ) from 4.4 to 5.3 points (P < 0.001). Restless legs syndrome (RLS) prevalence increased from 21.0% to 31.2% (P = 0.038). In contrast, insomnia symptoms, circadian timing and total sleep time remained stable. In multivariate logistic regression, excessive daytime sleepiness was independently associated with depressive symptoms, use of dopamine agonists, and risk of sleep apnea. CONCLUSION: Sleep disturbances in PD show a selective pattern of progression over 5 years. Daytime sleepiness, napping, RLS symptoms, sleep talking, nightmares and RBDSQ score increase while insomnia symptoms remain stable. These findings highlight the need for longitudinal, multi-domain sleep assessment in PD clinical care. The longitudinal increase in RBD-related symptoms and sleep talking strengthens their utility as markers of disease progression and clinical prognostic relevance. CURRENT KNOWLEDGE/STUDY RATIONALE: Sleep disturbances are among the most frequent and disabling non-motor symptoms of Parkinson's disease. These include insomnia, excessive daytime sleepiness, REM sleep behavior disorder, and restless legs syndrome. Long-term prospective data on how multiple sleep disorders and sleep characteristics evolve over time in PD is lacking. STUDY IMPACT: In this 5-year prospective cohort study sleep disturbances in PD progress selectively. Daytime sleepiness, napping, restless legs syndrome, sleep talking, nightmares and RBD-related features worsen significantly while insomnia symptoms remain stable. This provides evidence that sleep characteristics and disorders evolve in time. Sleep disturbances in PD should be assessed routinely in clinical practice.