The aim of this study was to evaluate the association between chronotype, stress, sleep and social jetlag (SJL) in Bulgarian sports students. In total, 29 male and female university students were surveyed using the Horne-Ostberg morningness-eveningness questionnaire, smart watch for measuring the peripheral skin temperature, perceived stress scale (PSS), Pittsburgh sleep quality index (PSQI) and a self-report questionnaire to determine SJL. It was determined that 2 students were morning type (MT), 7 were evening type (ET) and 20 were intermediate type (IT). Temperature measurements confirmed that. Mann-Whitney U test showed an association between stress scores and gender groups, PSQI scores showed association with PSS groups, chronotype and SJL. Females were more stressed than males. Students with high SJL levels (n = 7) were ET (n = 5). In our sample ET (n = 7) were more than MT (n = 2). Usually athletes tend to be MT. Age has a great influence in chronotype expression. ET perceived more stress and experienced more frequent daytime dysfunction than MT and IT. Collectively, these results suggest that stress levels are higher when imbalance exists between more than one circadian rhythm disruption indicators. Also training schedules should be arranged when taking into account circadian preferences.
Zaharinova et al. (2026) studied this question.