0029 Bimodality in Undergraduate Students Is Associated with Negative Health and Sleep Outcomes

Abstract Introduction The bimodal chronotype is a fourth circadian phenotype proposed by re-scoring the Morningness-Eveningness Questionnaire as first described by Martynhak and colleagues in 2010. Bimodal subjects are classified as “intermediate”, but they answer some of the questions as a morning person and others as an evening person. The present work aimed to describe the prevalence of the bimodal chronotype in a sample of undergraduate students in the city of Sao Paulo and to characterize the bimodal type in terms of their health and sleep-related outcomes. Methods A web-based cross-sectional study conducted between September 2018 and March 2021, using a convenience sampling method. The sample was composed of undergraduate students from two higher education institutions in Sao Paulo, 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). Results Of the 615 students, 108 (18%) had positive bimodality indexes. Bimodal subjects comprised 48 students (79% female, 19% male, 2% other gender), 8% of the total sample. Bimodal subjects had poorer subjective sleep quality (F(3,598)=20.0 p 0.001), more daytime sleepiness (F(3,611)=7.1 p 0.001), lower subjective well-being (F(3,611)=14.0 p 0.001), greater anxiety (F(3,611)=9.6 p 0.001) and depression symptoms (F(3,611)=11.8 p 0.001), and lower self-compassion (F(3,611)=10.1 p 0.001) than morning and/or intermediate types. However, they did not differ from evening types. Conclusion We found a bimodality prevalence of 8% and show that this profile is associated with negative health and sleep outcomes. The description of bimodality prevalence in a sample of college students is interesting because they are often an at-risk population for abnormal sleep and circadian disruption, which may be of interest for the design of academic public policies more consistent with the circadian reality of students. Support (if any) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Associação Fundo de Incentivo à Pesquisa (AFIP).