Background/Aims Health-impairing lifestyle during adolescence is an important marker for poor health. An unhealthy lifestyle may lead to physical and psychological problems in adulthood. Most of the prior researches were done among the adult population. Therefore, we assessed the chronotype pattern and correlation of health-impairing lifestyles with sleep quality according to circadian typology in medical students. Material and Methods In this cross-sectional research, a total of 203 subjects were enrolled. All subjects were divided into definite evening chronotype (n = 73), intermediate chronotype (n = 87), and definite morning chronotype (n = 43). Electronic media use at bedtime and duration of media use, the timing of dinner, smoking, tobacco chewing, and alcohol consumption were assessed with the help of a preformed proforma. Physical activity, sleep quality, daytime sleepiness, and chronotype were assessed by International Physical Activity Questionnaire (IPAQ), Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Score (ESS), and Morningness-Eveningness Questionnaire Self-assessment version (MEQ-SA), respectively. Results Subjects of the evening chronotype were suffering more with poor sleep quality. Evening chronotype had a significant (p < 0.05) positive correlation between poor sleep quality and sex, tobacco smoking, alcohol drinking, type of diet, and timing of dinner. Conclusion Circadian typology demonstrated the significant correlation of health-impairing lifestyles with sleep quality. From this observation, it might be a better way to plan their daily activities, in accordance with their chronotypes, benefiting not only their academic performance but also their quality of life.
