Bimodal diurnal preference in undergraduate students is associated with negative health and sleep outcomes.

The bimodal preference is a fourth diurnal preference proposed by re-scoring the Morningness-Eveningness Questionnaire. The present work aimed to describe the prevalence of the bimodal preference in a sample of undergraduate students and to characterize the bimodal type in terms of their health and sleep-related outcomes. A web-based cross-sectional study conducted between September 2018 and March 2021 (convenience sampling method). The sample was composed of undergraduate students who completed an electronic form that included the Morningness and Eveningness Questionnaire, the Pittsburgh Sleep Quality Index, the Self-Compassion Scale, the Epworth Sleepiness Scale, the Hospital Anxiety and Depression Scale, and the World Health Organization Subjective Well-Being Index. The final sample consisted of 615 students (82% female, mean age: 23.4 ± 6.5 years), of whom 108 (18%) had positive bimodality indexes. Bimodal subjects comprised 48 students, 8% of the total sample. Bimodal subjects had poorer subjective sleep quality, more daytime sleepiness, lower subjective well-being, greater anxiety and depression symptoms, and lower self-compassion than morning and/or intermediate types; they did not differ from evening types. The description of bimodal diurnal preference in this population may be of interest for the design of academic policies more in line with the circadian reality of students.

Mediation analysis of circadian preferences and other behavioral and sociodemographic factors associated with subjective well-being in undergraduate students.

Undergraduate students are usually subjected to a routine with constant pressure, stress, circadian misalignment, and sleep irregularity that impairs their subjective well-being. Recent evidence suggests that circadian preference is also a risk factor for impaired mental health and factors related to subjective well-being. This study aimed to identify the sociodemographic factors associated with subjective well-being and describe the mediating behavioral variables. Between September 2018 and March 2021, 615 Brazilian students enrolled in higher educational institutions completed an electronic form containing questionnaires on subjective well-being, sociodemographic, and behavioral-related factors (convenience sample). A statistical mediation model was applied to describe how these variables influence subjective well-being. We observed that Morningness (p < .001), identification with the male gender (p = .010), not working while studying (p = .048), and the practice of Pilates/yoga (p = .028) were associated with greater subjective well-being. Except for employment status, no direct effects were observed, which reinforces the need to consider a multidimensional approach. The relationship between subjective well-being and sociodemographic factors exists only in the presence of behavioral mediators, specifically perceived stress, daytime sleepiness, symptoms of depression, sleep quality, and positive and negative affects. Future work should investigate in more detail the impact of sleep, stress, and circadian preferences on this relationship.