What goes bump in the night? In many U.S. households: people. About 3.6 percent of US adults — or upward of 8.4 million — are prone to sleepwalking, new research shows. The work also showed an association between nocturnal wanderings and certain psychiatric disorders, such as depression and anxiety. A large number of people reported sleepwalking in childhood or adolescence making the lifetime prevalence of sleepwalking 29.2 percent.