Idiopathic rapid eye movement sleep behavior disorder (iRBD) is characterized by nocturnal violence, increased muscle tone during REM sleep and the lack of any other neurological disease. However, iRBD can precede parkinsonism and dementia by several years. The causes of the loss of muscle atonia during REM sleep in these patients are unclear. Using 3 T MRI and neuromelanin- sensitive sequences, the signal intensity was previously found to be reduce in the locus coeruleus/subcoeruleus area of patients with Parkinson's disease and RBD. Here, the investigators aimed at studying the integrity of the locus coeruleus/ subcoeruleus complex with neuromelanin-sensitive imaging in 21 patients with iRBD and compared the results with those from 21 age- and gender-matched healthy volunteers. All subjects will undergo a clinical examination, motor, cognitive, autonomous, psychological, olfactory and color vision tests, and rapid eye movement sleep characterization using video-polysomnography and 3 T magnetic resonance imaging.

Inclusion Criteria:

- idiopathic RBD (criteria of the international classification of sleep disorders-3)

For healthy controls : no neurologic or psychiatric disorder

Exclusion Criteria:

• Contraindication to MRI
• Do not speak French