The differential diagnosis of each form of parkinsonism at onset may be difficult for clinicians because the evolution of different features may vary widely and clinical and instrumental markers predictive for a specific syndrome are still lacking. Parkinsonisms may exhibit a variety of non-motor symptoms, such as sleep disturbances, that may be present since the early stage of disease. Objective of this prospective single centre observational study is to describe the possible diagnostic value of sleep disturbances in patients with recent-onset parkinsonism. This study suggests that REM sleep motor control is more frequently impaired at disease onset in patients with atypical parkinsonism than in patients with Parkinson disease. The evaluation of sleep disorders, with an in-depth clinical interview followed by video-polysomnography, may be a useful tool in the differential diagnosis of parkinsonism at onset.