In this proposed study, the investigators aim to build up a large cohort of Rapid eye movement sleep behavior disorder (RBD) to study the etiology and risk factors of neurodegeneration.

REM sleep behavior disorder (RBD) is a parasomnia characterized by abnormal behavioral manifestations during REM sleep. Accumulating evidence suggests that RBD is implicated as an integral part of disease progress of α-synucleinopathy neurodegeneration, such as Parkinson's disease (PD) and dementia with Lewy bodies.Previous studies have identified a series of neurocognitive, autonomic, clinical and neurobiological markers for neurodegeneration in iRBD, such as olfactory dysfunction, color vision deficit, autonomic dysfunction, tonic EMG activity during REM sleep, and psychiatric disorder. However, the prevalence rate of RBD was relatively low and most of the RBD studies only have 100 or below cases. and there might be ethic differences in RBD which indicates that the findings from western countries might not be applicable to Chinese. In these regards, the investigators aimed to build up a large cohort of Rapid eye movement sleep behavior disorder (RBD) to study the etiology and risk factors of neurodegeneration.

Inclusion Criteria:

Case: According to the ICSD-3 for the diagnosis of RBD

1. Sleep talking or complex movement during sleep;
2. Such movement was recorded by video PSG (AV-PSG) during REM sleep or according to history the movements were occurred during REM;
3. REM sleep without atonia (RWA) during PSG monitoring;
4. This abnormal phenomenon cannot be explained by other sleep disorder, psychiatric disease, drug or substance abuse.

Control: Age and gender matched with consent

1. No RBD symptoms and PSG characteristics;
2. No neurological symptoms or diseases, MRI scan will be employed to exclude brain pathology;
3. No narcolepsy or hypersomnia, ruled out by multiple sleep latency test;
4. No history of mental illnesses or use of antidepressants.

Exclusion Criteria:

1. Subjects who refused to join the cohort.

Subjects will be recruited from psychiatry outpatient clinics, Prince of Wales Hospital and 11 collaborated sites in mainland China.

Researcher in other sleep centers are also conducting similar study, there may be a plan for further collaboration on sharing the database