The effect of bullying victimization on sleep quality among Chinese medical students: Timing, duration, and patterns

Background: Bullying victimization (BV) is a potential factor to sleep quality, but the role of BV characteristics in this association remains unclear. This study aimed to investigate correlation between the timing, duration, and patterns of BV and sleep quality among Chinese medical students. Methods: 4035 participants (mean age of 19.2 +/- 1.0) were recruited. BV patterns from pre-school to college were estimated using latent class analysis. Multinomial logistic regression was conducted to evaluate the odds ratio (OR) and 95 % confidence interval (CI) between sleep quality and BV. E values were used to assess unmeasured confounding. Results: Three patterns of BV were identified as follows: persistent BV (6.2 %), moderate BV (10.5 %), and low BV (83.3 %). BV during pre-school, elementary school, junior high school, senior high school, and college were all positively associated with poor sleep quality. The ORs were 2.30 (1.43-3.70), 3.00 (2.28-3.95), 2.71 (2.14-3.43), 3.34 (2.57-4.33) and 4.13 (3.19-5.36), respectively. The E value were 4.03 (2.21-NA), 5.45 (3.99NA), 4.86 (3.70-NA), 6.14 (4.58-NA), 7.73 (5.83-NA), respectively. Those who experienced more periods of BV were more strongly associated with poor sleep quality, presenting a dose-response relationship [OR = 1.78, 95 % CI: 1.63-1.95, E value: 2.96 (2.64-NA)]. Those who experienced moderate BV [OR = 2.58, 95 % CI: 1.99-3.35; E value: 4.60 (3.39-NA)] and persistent BV [OR = 4.01, 95 % CI: 2.95-5.46; E value: 7.48(5.35-NA)] had higher odds of poor sleep quality. Limitations: Retrospective design may introduce recall bias. Conclusion: BV was positively related to poor sleep quality and chronic exposure to BV had a cumulative effect on poor sleep quality.