Chronotype reflects the morningness–eveningness preference over a 24 h period. Significant data indicate meaningful differences between evening types (ETs) and morning types (MTs) in behavior, personality traits, health, and well-being. This study explores the interactions between chronotype, sleep, personality, and life satisfaction among 254 undergraduate college students (mean age 23.79 ± 1.85). Using online questionnaires, the participants provided demographic information and completed assessments, including the Morningness–Eveningness Questionnaire (MEQ), the Pittsburg Sleep Quality Index (PSQI), a shortened version of the Big Five Inventory (BFI-10), and a life satisfaction uniscale measure. The results revealed a significant association between chronotype and both life satisfaction and sleep quality, where ETs exhibited poorer outcomes compared to MTs. Additionally, the chronotype correlated with agreeableness and conscientiousness, with later chronotypes linked to reduced scores in these personality traits. A key finding in this study was revealed in a mediation analysis in which sleep quality was found to mediate the relationship between chronotype and life satisfaction. The mediation analysis highlighted sleep quality as a crucial process connecting chronotype to life satisfaction. The findings emphasize the importance of addressing sleep quality in interventions aimed at enhancing life satisfaction and overall well-being among ETs. Overall, our results provide valuable insights into the intricate relationships between chronotype, personality, sleep quality, and subjective well-being.

Background: Evening chronotypes are increasingly recognized as being at elevated risk of psychological vulnerabilities, including sleep disturbances, mood disorders, and disordered eating. Body image, a central self-related construct, has been identified as a key factor influencing eating disorder (ED) risk. This study aimed to explore whether body image moderates the relationship between chronotype and the risk of developing an ED. Methods: A total of 165 adults (139 women; mean age = 35.45) completed validated self-report questionnaires assessing chronotype (Morningness–Eveningness Questionnaire), body image (Body Shape Questionnaire), and ED risk (EAT-26). Pearson correlations and moderation analyses (PROCESS macro and Model 1) were conducted with body image as a moderator of the association between chronotype and ED risk. Results: Eveningness was significantly associated with greater ED risk (r = −0.53, p < 0.001) and a more negative body image (r = −0.48, p < 0.001). Body image was a strong predictor of ED risk (r = 0.85, p < 0.001). Moderation analysis revealed a significant interaction between chronotype and body image (b = −0.006, SE = 0.0009, p < 0.001), indicating that the relationship between chronotype and ED risk was stronger among individuals with a more negative body image. Conclusions: These findings highlight the role of body image as a moderating factor in the link between chronotype and eating disorder vulnerability. Interventions aimed at improving body image, especially among evening chronotypes, may help mitigate ED risk. These results underscore the importance of integrating circadian and psychosocial factors in ED prevention and early intervention strategies.

Introduction: This study aimed to examine the associations among binge eating behaviors (BEBs), emotion regulation (ER), and chronotypes, and whether ER mediates the relationship between chronotypes and BEBs in Greek female university students, a population in which these associations have not previously been investigated. Methods: This study was approved by the Research and Ethics Committee of the Medical School of Aristotle University of Thessaloniki (No. 91/23, dated 17/02/2023). A total of 269 female students [mean age (±SD) = 21.06 (±4.35)] from Aristotle University of Thessaloniki participated in this cross-sectional study. Participants completed a sociodemographic questionnaire and four validated instruments: the Eating Disorder Examination Questionnaire, the Binge Eating Scale, the Difficulties in Emotion Regulation Scale, and the Morningness-Eveningness Questionnaire. Results: BEBs were significantly correlated with eating psychopathology (rs = 0.723, p < 0.001) and with difficulties in emotion regulation (ER) (rs = 0.429, p < 0.001). ER difficulties were also associated with eating psychopathology (rs = 0.434, p < 0.001). An evening chronotype was significantly associated with greater ER difficulties (rs = –0.150, 0.014). Mediation analysis indicated that ER difficulties fully mediated the relationship between eveningness and BEBs (Indirect Effect = –0.06, 95% CI: –0.11 to –0.01). Discussion: ER difficulties are associated with both BEBs and eveningness. While eveningness is not directly associated with BEBs, it is indirectly related through ER difficulties, suggesting a potential psychological mechanism underlying this relationship. Conclusion: ER difficulties may be a key mechanism linking evening chronotype to BEBs. Future studies could explore whether interventions targeting ER and circadian alignment are beneficial for managing BEBs among individuals with an evening chronotype.

Chronotype determines morningness-eveningness preference over a 24-h period. Significant data indicates meaningful differences between evening types (ET) and morning types (MT) in behavior, personality traits, health and well-being. The aim of this study was to investigate cortisol response and subjective perceived stress of MT and ET individuals in response to an acute natural stressor. Twenty six definite MT and twenty six definite ET college students were recruited for this study. Participants were instructed to evaluate their perceived subjective stress and to provide saliva samples for cortisol levels at four different time points: Morning of regular school day, morning immediately before a final exam, afternoon of a regular school day and afternoon immediately before a final exam. For general mood assessment, the participants were also asked to fill out the Positive and Negative Affect Schedule (PANAS) questionnaire. The most outstanding finding of this study was the blunting of cortisol increase in response to acute stress in the morning in the ET group: Salivary cortisol was higher before a final exam only in MT but not in ET. However, no differences between the groups were found in the subjective stress measure. In the PANAS scale, ET showed lower positive affect, and a trend towards a higher negative affect. Overall, our results suggest dysregulation of the HPA axis in ET individuals, possibly due to their daily struggle to function in a morning-oriented society. These results further highlight the challenges faced by ET individuals and raise the question of possible interventions to assist them.