Effect of chronotype on diet and sleep quality in healthy female students: night lark versus early bird

Abstract

Purpose The purpose of this study is to investigate the effects of chronotype on diet and sleep quality in healthy female students. Design/methodology/approach This study was conducted in 197 healthy female students and were grouped in morning, intermediate and evening types according to the Horne and Ostberg Morningness-Eveningness Questionnaire (MEQ). Assessment included sleep quality using the Pittsburgh Sleep Quality Index (PSQI); physical activity level using the International Physical Activity Questionnaire-Short Form (IPAQ-SF); dietary intake using the 24-h dietary recall; and diet quality using the Healthy Eating Index-2015 (HEI-2015). Findings In this study, no significant difference was found between chronotypes in terms of general nutritional habits, age, smoking status, anthropometric measurements and physical activity levels. However, evening-type individuals had poor sleep quality (p = 0.040) and having issues about sleep latency (p = 0.049) and daytime dysfunction (p = 0.044), and they had had lower intake of whole fruit (p = 0.002), total fruit (p = 0.024) and higher consumption of refined grains (p < 0.001). Although, among chronotypes, there is no difference in the intake of protein, saturated fat, monounsaturated fatty acids, polyunsaturated fatty acids and dietary fiber, evening-type individuals’ daily energy (p = 0.013), fat (p = 0.021) and carbohydrate intake (p = 0.033) were higher. Originality/value In conclusion, further research is required to understand the relationship between chronotype, diet and sleep quality. This study is one of the limited studies that examines sleep quality, daily energy and macronutrient intake and diet quality together for healthy women.