Caffeine, Sleep, and Academic Performance: A Cross-Sectional Study Among University Students

Aim: Caffeine is a psychoactive substance frequently consumed by students to increase alertness and support academic performance. However, the effects of caffeine consumption on sleep quality, circadian rhythm, social jetlag, and academic achievement have not yet been clearly established. This study aimed to determine university students' caffeine intake levels and evaluate the relationships between these levels and sleep quality, circadian rhythm, social jetlag, and academic achievement. Material and Method: This cross-sectional and descriptive study was conducted in Ankara between 2024–2025, and 457 university students were included in the study. Data were collected using a sociodemographic form, a quantitative caffeine intake frequency questionnaire, the Pittsburg Sleep Quality Index (PSQI), the Morningness-Eveningness Questionnaire (MEQ), and the Social Jetlag Form. Academic achievement was assessed using the general grade point average (GPA). Data were analyzed using SPSS 26. Results: Positive significant relationships were found between caffeine intake and PSQI and social jetlag, and negative significant relationships were found with MEQ scores (p<0.05). No significant relationship was found between caffeine intake and academic success. The regression analysis determined that only the MEQ score had a positive significant effect on academic success (β=0.173, p<0.001). Conclusion: Caffeine intake affects students' sleep and circadian parameters; however, these effects are not directly reflected in academic success. The contribution of morningness to academic success is emphasized, and biological rhythms should be considered in the future education system.