Associations between fluctuations in daytime sleepiness and motor and non-motor symptoms in Parkinson's disease

Background: Non-motor fluctuations are a major concern in Parkinson's disease (PD), and they have been categorized into neuropsychiatric, autonomic and sensory fluctuations. However, this categorization does not include sleep and sleep-related features, and the association between daytime sleepiness and other motor and/or non-motor fluctuations in PD remains to be elucidated. Objective: To investigate the relationship between daytime sleepiness and other non-motor and motor fluctuations in people with PD. Methods: A three-day home diary recording daytime sleepiness, mood, anxiety, and motor symptoms was used along with the Karolinska Sleepiness Scale (KSS) and 6 days of accelerometer (Parkinson's KinetiGraph™; PKG™) registration to detect motor fluctuations among people with a DaTSCAN verified clinical PD diagnosis (32 men; mean PD duration, 8.2 years). Participants were categorized as motor fluctuators or non-fluctuators according to the UPDRS part IV and/or the presence of motor and non-motor fluctuations. Results: Fifty-two people with PD participated. Daytime sleepiness correlated significantly with motor symptoms, mood and anxiety among those classified as motor fluctuators (n = 28). Motor fluctuators showed stronger correlations between the individual mean level of all diary variables (daytime sleepiness, anxiety, mood and motor symptoms) when compared to the non-fluctuators (n = 24). Stronger positive within-individual correlations were found among fluctuators in comparison to non-fluctuators. In general, PKG data did not correlate with diary data. Conclusion: Episodes of daytime sleepiness, as reported by home diaries, were associated with other self-reported non-motor and motor fluctuations, but were not supported by PKG data.