Background: Depressive symptoms typically exhibit sex differences among medical students and are associated with bedtime procrastination (BP) and self-control. However, it remains unclear whether sex differences exist in the relationship between these variables.
Methods: A cross-sectional observational study was conducted among 402 medical students from a public university in China. Students' depressive symptoms, BP, and trait self-control were assessed using the Chinese version of the Beck Depression Inventory (BDI)-II, the Bedtime Procrastination Scale, and the Self-control Scale, respectively. Applying a BDI cutoff value of 14, 364 valid participants were divided into non-depressed (<14) and depressed (≥14) groups.
Results: Binary logistic regression revealed that BP was an independent predictor of the prevalence of depressive symptoms in women only. Hierarchical regression showed that high BP levels were independently positively correlated to more depressive symptoms only in non-depressed women. In contrast, low self-control levels were independently negatively correlated to more depressive symptoms in non-depressed and depressed female students. Furthermore, structural equation modeling reflected the mediating role of BP between self-control and depressive symptoms in the non-depressed female group only.
Conclusions: Sex differences exist in the effect of BP on depressive symptoms as well as the relationship between self-control and depressive symptoms among Chinese medical students. As a moderator, sex regulates the mediating effect of BP on the relationship between self-control and depressive symptoms in the non-depressed group. These findings provide a sex-specific perspective for targeted prevention and intervention of depressive symptoms among high-risk medical students, especially during the non-depressed period.
Keywords: Bedtime procrastination; Depressive symptoms; Mediation; Moderator; Self-control; Sex difference.
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