Objective: To assess the prevalence and comorbid conditions of nocturnal wandering with abnormal state of consciousness (NW) in the American general population. Methods: Cross-sectional study conducted with a representative sample of 19,136 noninstitutionalized individuals of the US general population 18 years old. The Sleep-EVAL expert system administered questions on life and sleeping habits; health; and sleep, mental, and organic disorders (DSM-IV-TR; International Classification of Sleep Disorders, version 2; International Classification of Diseases-10). Results: Lifetime prevalence of NW was 29.2% (95% confidence interval [CI] 28.5%-29.9%). In the previous year, NW was reported by 3.6% (3.3%-3.9%) of the sample: 1% had 2 or more episodes per month and 2.6% had between 1 and 12 episodes in the previous year. Family history of NW was reported by 30.5% of NW participants. Individuals with obstructive sleep apnea syndrome (odds ratio [OR] 3.9), circadian rhythm sleep disorder (OR 3.4), insomnia disorder (OR 2.1), alcohol abuse/dependence (OR 3.5), major depressive disorder (MDD) (OR 3.5), obsessivecompulsive disorder (OCD) (OR 3.9), or using over-The-counter sleeping pills (OR 2.5) or selective serotonin reuptake inhibitor (SSRI) antidepressants (OR 3.0) were at higher risk of frequent NW episodes (2 times/month). Conclusions: With a rate of 29.2%, lifetime prevalence ofNWis high. SSRIs were associated with an increased risk of NW. However, these medications appear to precipitate events in individuals with a prior history of NW. Furthermore, MDD and OCD were associated with significantly greater risk of NW, and this was not due to the use of psychotropic medication. These psychiatric associations imply an increased risk due to sleep disturbance.