Larks or owls? That is the question – Chronotype, sleep, and mental health of international students

Introduction: The aim of this study was to investigate the role of "morningness" and "eveningness" chronotype preferences in the associated risk of sleep disorders and stress in international students. Methodology: The study was conducted at the University of Jaen, Spain (September-November 2023), with the participation of 185 international students, mean age (23.19±5.47), of whom 70 (37.8%) were female. The Morningness/Eveningness Questionnaire (MEQ), the Epworth Sleepiness Scale (ESS), the Pre-Sleep Arousal Scale (PSAS), and the Student-Life Stress Inventory (SLSI) were used in the study. Results: 50 (27%) of the sample were classified as moderate evening types, 5 (2.7%) as moderately morning types, and 130 (70.3%) as intermediate chronotypes. The later chronotype subjects presented significantly higher indicators in all the study variables. Although the ESS scores in both groups were below the cutoff (>11), the moderately evening type samples reported higher levels of excessive daytime sleepiness than morning type samples (7.66±2.98 and 6.8±4.08, respectively). Moderately evening type subjects reported both Somatic (16.82±5.22 vs. 13.4±3.5) and Cognitive (23.42±7.65 vs. 19.8±3.03) PSAS, as well as Total PSAS (40.24±12.01 vs. 33.2±6.34). All evening type subjects reported a high level of Total SLSI score (129.04±22.69 vs. 119.4±20.97), as well as scores across all stress categories. Almost all study variables were significantly higher in males. Conclusion: International students with a late chronotype face more stress and sleep issues than those with an early one. Further research is needed to explore chronotype's impact on students' health.