The eveningness chronotype is associated with nightmare distress and dream recall: a cross-sectional study.

Dreaming may be affected by sleep behavior; however, evidence of the effect of chronotypes on dreaming is limited. We investigated sleep patterns, dream recall, and nightmare distress according to chronotypes. This cross-sectional study retrospectively enrolled adult participants (age > 18 years) who visited a sleep laboratory between 2016 and 2021 and underwent standard polysomnography (PSG) and completed a self-reported questionnaire. Patients with major sleep disorders were excluded. Chronotypes and dreaming components were assessed using the Korean version of the morningness-eveningness questionnaire and a nine-item dreaming questionnaire (nightmare distress and dream recall), respectively. Among healthy participants without major sleep disorders, the eveningness chronotype correlated with better dream recall than the morningness and intermediate chronotypes. Participants with the eveningness chronotype were younger and more likely to be unmarried than those with the other chronotypes. No significant chronotype-based difference was observed in the subjective measurements of sleep quality, insomnia, daytime sleepiness, depression, and anxiety or in respiration and movement events on PSG. In multivariate linear regression analysis, the chronotypes were independently related to nightmare distress (b = - 0.296; p = 0.002) and dream recall (b = - 0.334; p = 0.002). The apnea-hypopnea index was associated with nightmare distress (b = - 0.209; p = 0.029) and dream recall (b = - 0.189; p = 0.044). Depression was positively correlated with nightmare distress (b = 0.450; p = 0.002). Dream recall was best in the eveningness group among healthy adults. Greater eveningness was associated with higher nightmare distress and better dream recall. Further research is needed to understand the role of chronotypes in dreaming.