The effects of chronotype and social jetlag on medical students

Abstract

The aim of our study is (1) to identify chronotypes and social jetlag of Korean medical students and (2) to investigate the effect of chronotypes and social jetlag on sleep, quality of life (QoL), and academic performance of medical students. The final sample consisted of 424 students of a single medical school, assessed by 8 questionnaires: demographic questionnaire, Morningness–Eveningness Questionnaire (MEQ), Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Insomnia Severity Index (ISI), Short Form (SF)-8 health survey, Warwick–Edinburgh Mental Well-Being Scale (WEMWBS), and Beck Depression Index (BDI)-2. Eight (1.9%) were “morning type (MT)”, 247 (58.3%) were “intermediate type (IT)”, and 169 (39.9%) were “evening-type (ET)”. The social jetlag of the ET group was longest (1.75\xa0h) compared to the other groups. In the ET group, social jetlag of medical course (MC, 4\xa0years) was significantly longer than in pre-med course (PM, 2\xa0years). Curriculum changes from PM to MC and chronotypes show interactions in bedtime during weekend and subjective sleep quality/sleep latency subscore of PSQI. In the MT\u2009+\u2009IT group, compared with pre-med students, the top 25% of academic performance in medical school students significantly increased (19.7% vs. 30.2%), while the ET group did not show such a difference. The chronotype was related to social jetlag, sleep quality, daytime sleepiness, and academic performance of medical students. ET students are more vulnerable to lower sleep quality to curriculum change from PM to MC.