Real‐world sleep in Parkinson’s disease predicts cognitive dysfunction.

Sleep dysfunction is signature of Alzheimer’s disease and Parkinson’s disease (PD), and can signify incipient disease, disease risk, and worsen symptoms over time. How real‐world sleep dysfunction relates to patient self‐report of sleep and clinical cognitive dysfunction is poorly understood, partly because self ‐report is impaired in patients with cognitive decline. We monitored real‐world sleep with wearable actigraphy devices in patients with PD to test the hypothesis that objective patterns of sleep dysfunction are associated with worse cognitive performance.