An Immature Defense Style Is Related to Poor Sleep Quality in Medical Students

Objective: Poor sleep quality is highly prevalent among medical students. Certain personality features, such as defense styles and mechanisms, may be related to poor sleep quality among medical students. Methods: In total, 146 medical students (45 female, 30.8%) participated in this study. The students completed the Korean version of the Defense Style Questionnaire in their first year and Insomnia Severity Index (ISI), Beck Depression Inventory-II, Beck Anxiety Inventory, and the Composite Scale of Morningness in their third year. Results: Multiple linear regression analysis revealed that immature defense style (β=0.210, t=2.931, p=0.004) was related to poor sleep quality (i.e., higher ISI score) among the students after controlling for age, sex, depression, anxiety, and chronotype. Regarding defense mechanisms, multiple linear regression analysis revealed that lower sublimation (β=-0.153, t=-2.211, p=0.029), greater humor (β=0.180, t=2.561, p=0.012), and higher withdrawal (β=0.173, t=2.511, p=0.013) were related to poorer sleep quality after controlling for age, sex, depression, anxiety, and chronotype. Conclusion: An immature defense style could be a risk factor for developing insomnia in medical students. Sublimation may protect against insomnia, whereas humor and withdrawal could be risk factors for insomnia.