Investigating the relationship between sleep habits and the frequency and expression of hallucinatory-like...

Sleep habits have emerged as robust correlates of hallucinatory phenomena. Hallucinations, while commonly studied in clinical populations, also occur in the general population as Hallucinatory-Like Experiences (HLEs), which vary in frequency and expression. Although poor sleep quality has been linked to increased occurrence of HLEs, the specific role of habitual sleep patterns in shaping both the occurrence and subjective qualities of HLEs remains unclear. In a large non-clinical French sample (N = 1650), participants reported typical weekday and weekend sleep habits and completed measures of auditory and visual HLEs frequency and characteristics (i.e., vividness, emotional valence, control, source location, agency, distress, confidence). Using multivariable regression models in which multiple sleep parameters were entered simultaneously, analyses showed that sleep fragmentation and later bedtimes were associated with HLEs frequency. Moreover, bedtime, sleep efficiency, the feeling of being woken up at night and weekend-to-weekday sleep duration variation were associated with specific features, such as negative emotional valence, increased distress, and external spatial location of the experience, even when controlling for HLEs frequency. These findings underscore the relationship between sleep quality, delayed bedtimes, and HLEs. From a sleep medicine perspective, they highlight sleep continuity and timing as key dimensions associated with both the frequency and subjective impact of HLEs. Moreover, they suggest that habitual sleep habits may serve as clinically informative indicators of vulnerability to HLEs in the general population.