Sleep−wake cycle dysregulation in idiopathic REM sleep behaviour disorder

Alteration of the circadian sleep−wake rhythm has been suggested in patients affected by idiopathic rapid eye movement sleep behaviour disorder. Because actigraphy is the validated instrument to monitor the sleep−wake cycle, the aim of the present study was to investigate the circadian sleep−wake rhythm in patients with idiopathic rapid eye movement sleep behaviour disorder compared with healthy aged controls. Fourteen-day actigraphic recording, a comprehensive sleep interview, and cognitive and behavioural domains were investigated in patients affected by idiopathic rapid eye movement sleep behaviour disorder, and compared with controls similar for age, sex and cognitive performances. Patients with idiopathic rapid eye movement sleep behaviour disorder showed reduced relative amplitude and alteration of both sleep and wake compared with controls. Patients with idiopathic rapid eye movement sleep behaviour disorder also showed subjective sleep and wake complaints, and higher scores at the Beck Depression Inventory, compared with controls. Beck Depression Inventory scores correlated with sleep actigraphic parameters, such as sleep latency, sleep efficiency, time in bed, and relative amplitude. Therefore, the present study showed the dysregulation of the sleep−wake cycle in patients with idiopathic rapid eye movement behaviour disorder. Moreover, depressive symptoms documented in patients with idiopathic rapid eye movement sleep behaviour disorder correlated with the sleep−wake rhythm dysregulation.