Abstract
Sleep and circadian rhythms are both considered to be important determinants of mental and physical health. Epidemiological studies characterise sleep by self-reported duration and quality whereas circadian aspects are often captured by self-reported chronotype. Several studies established the independent contribution of sleep duration, sleep quality or chronotype to health. A comparison of the relative contributions of sleep and circadian characteristics to health outcomes is currently not available. Mental health and sleep problems are more common in women than in men and men are more likely to be vening types than women. Few studies have explored sex differences in the associations between sleep-circadian characteristics and health. Here, sleep quality, chronotype, sleep duration and health and psychological wellbeing were assessed in 410 men and 261 women aged 18 to 30 by multiple questionnaires including the Morningness-Eveningness Questionnaire, Munich-ChronoType Questionnaire, Pittsburgh Sleep Quality Index, British Sleep Survey, Karolinska Sleep Diary, Insomnia Severity Index, SF-36 Health Survey, General Health Questionnaire, Dutch Eating-Behaviour Questionnaire, Big Five Inventory, Behaviour Inhibition System–Behaviour Activation System, and the Positive Affect-Negative Affect Schedule. Associations were assessed with multiple regression models and relative contributions of predictors were quantified as local effect sizes. Across all questionnaires, sleep quality was a much stronger independent predictor of health and in particular mental health than chronotype and sleep duration. The association between sleep quality and mental health was significant in both genders and significantly stronger in women than in men. A better understanding of subjective sleep quality may aid the understanding of sleep-health interactions.