Rest–activity disturbances correlate with core features in dementia with Lewy bodies

Background: Sleep–wake disturbances are a clinically important and poorly studied feature of dementia with Lewy bodies (DLB) due to the challenges of in-laboratory polysomnography in this population. Objectives: To compare rest–activity rhythms in DLB, Parkinson's disease (PD), and age-matched controls using home-based wrist actigraphy and examine their relationship with core clinical DLB features. Methods: Eleven DLB patients, 12 PD patients, and 11 age-matched controls underwent clinical assessment. Actigraphy data were obtained over 14 days and analyzed using nonparametric methods. Results: DLB patients demonstrated higher rest–activity rhythm fragmentation (P = 0.002) than controls and lower circadian amplitude (P = 0.011) than both PD and controls. Instability of rest–activity rhythm was positively correlated with hallucinations (P = 0.009) and cognitive fluctuations (P = 0.016) in DLB, and reduced daytime activity correlated with severity of motor parkinsonism (P = 0.013). No such correlations were observed in PD. Conclusions: Actigraphy detects distinct rest–activity rhythm disruptions in DLB, differentiating it from PD and controls. These measures are associated with the severity of core clinical features in DLB.