Objective: Idiopathic REM sleep behavior disorder (RBD) is a powerful marker of prodromal neurodegenerative synucleinopathy, with 80% of patients ultimately phenoconverting to defined disease. Several environmental risk factors for RBD have been suggested, but associations vary between studies. We assessed sociodemographic, socioeconomic and clinical correlates of RBD in a 30,000-subject national cohort. Methods: Subjects aged 45-85 years in Canada were collected as part of the Canadian Longitudinal Study on Aging. Possible RBD (pRBD) was screened with the RBD-1Q, a questionnaire with 94% specificity and 87% sensitivity. To improve diagnostic reliability, subjects screening positive for apnea or non-REM parasomnia (young onset pRBD), and subjects self-reporting dementia or Parkinson’s disease were excluded. A series of sociodemographic, life style and mental health variables were analysed cross-sectionally. Potential correlates were assessed via multivariable logistic regression. Results: Of 30,097 subjects, 958 (3.2%) had pRBD. Male sex (OR=2.14 ,95%CI=[1.84, 2.49]) and lower education (OR=0.95 [0.92, 0.98] were associated with pRBD. pRBD subjects had smoked more (total smoking years OR=1.006 [1.010, 1.011]) and were more likely to be moderate-heavy drinkers (OR=1.25 [1.03, 1.50]). There was a strong association between pRBD and self-reported antidepressant treatment for depression (OR=2.76 [2.22, 3.44]), psychological distress (OR=1.52 [1.37, 1.69]), mental illness (OR=2.08 [1.79, 2.41]), and post-traumatic stress disorder (OR=2.84 [2.55, 3.54]). Conclusions: Our study replicated previous reported associations between pRBD and smoking, low education and male sex, and found previously-unreported links with alcohol use and psychological distress. The risk factors for pRBD differ from those previously defined for neurodegenerative synucleinopathies.