Importance Sleep disturbances are recognized as a common nonmotor complaint in
Parkinson disease but their etiology is poorly understood. Objective To define the sleep and
circadian phenotype of patients with early-stage Parkinson disease. Design, Setting, and
Participants Initial assessment of sleep characteristics in a large population-representative
incident Parkinson disease cohort (N= 239) at the University of Cambridge, England,
followed by further comprehensive case-control sleep assessments in a subgroup of these …