Effects of Sleep and Social Jetlag on the Quality of Diet of Evening Graduate Students

Background and Objective Chronotype, sleep, and diet are interconnected. Social demands, such as work or school, often hinder alignment with biological rhythms, potentially harming dietary habits and health. This study investigated the association between chronotype and social jetlag in undergraduate students and their impact on diet.Methods Sixty-three young adults (40 females), who studied at night and worked during the week, participated. Chronotype, social jetlag, sleep quality, and daytime sleepiness were assessed through validated questionnaires. A 1-week sleep and food diary evaluated sleep and dietary intake.Results Most students were classified as good sleepers, despite excessive daytime sleepiness. The majority had an intermediate chronotype and social jetlag exceeding 1 hour (median: 1.57 h; range: 0.05–4.02 h). On free days, participants woke later, slept longer, and had later sleep midpoints compared to workdays (p<0.001). Social jetlag was negatively correlated with chronotype (p=0.009), but not with sleep quality, efficiency, or daytime sleepiness. Negative correlations were observed between protein, lipid, and energy intake and sleep latency on day 1. On day 4, higher carbohydrate, lipid, and energy intake were associated with later bedtimes, and lipid and energy intake were negatively correlated with sleep latency. Social jetlag was also negatively correlated with weekly average intake of carbohydrates (p=0.05), protein (p=0.03), and energy (p=0.03).Conclusions Social demands affected biological rhythms, leading to social jetlag exceeding one hour in most participants, especially in evening chronotypes. While no clear links were found with sleep quality, observed diet–sleep correlations suggest dietary intake may influence sleep timing and latency.