Disruption of sleep-wake continuum in myotonic dystrophy type 1: Beyond conventional sleep staging.

•Sleep disruption and daytime sleepiness are prominent in myotonic dystrophy type 1.•We confirm increased REM sleep duration and SOREMs in DM1 patients.•NREM sleep instability is increased with slower delta power decline.•REM sleep alterations and daytime sleepiness confirm a narcoleptic-like phenotype.•Primary dysfunction of NREM sleep is suggested by peculiar microstructural pattern.