Background and Objectives: Despite the growing importance of postural research in adolescents, the impact of sleep quality on head posture during classroom sitting remains a research gap. The present study aimed to investigate the relationship between sleep quality and head posture during classroom sitting in female high school students.

Subjects and Methods: This descriptive-analytical cross-sectional study was conducted on 442 female students aged 15 to 18 years in Tehran high schools. Head posture was assessed using lateral photography and craniovertebral angle measurement. Sleep quality was evaluated using the Pittsburgh Sleep Quality Index. Data were analyzed using independent t-tests, ANOVA, and Pearson's correlation coefficient.

Results: The findings showed that 54.3% of participants had poor sleep quality. The mean craniovertebral angle was significantly lower in the poor sleep quality group compared to the good sleep quality group (40.32 ± 5.03 vs. 45.62 ± 5.33; P<0.001). Additionally, a significant inverse correlation was found between the total Pittsburgh Sleep Quality Index score and craniovertebral angle (r = -0.47, P<0.001). Comparison of the Pittsburgh Sleep Quality Index components revealed that students with poor sleep quality had significantly higher scores across all components, particularly sleep disturbances, subjective sleep quality, and daytime dysfunction, and these components demonstrated the strongest correlations with the craniovertebral angle.

Conclusion: The significant inverse association between sleep quality and craniovertebral angle highlights the role of sleep in postural control. Therefore, interventions aimed at improving sleep quality and correcting postural alignment in schools appear to be essential.