Background <p>Insufficient sleep is a common public health issue among students, and it is necessary to investigate this phenomenon and its consequences. Therefore, the present study aimed to examine the psychological consequences (i.e., somatization, depression, anxiety, and hostility) of insufficient sleep in medical students.</p> Methods <p>The sample in this cross-sectional study consisted of 448 college students (with a mean age of 23.47 years; 56.7% female) from Kermanshah University of Medical Sciences at Iran. Symptom Checklist-90-Revised Form (SCL-90-R) and several self-report questionnaires (physical activity, bedtime, sleep duration, and daily nap) were used to collect data, and the results were analyzed using ANOVA and ANCOVA.</p> Results <p>The results showed statistically significant differences in the mean scores of anxiety (F = 10.84, η² = 0.070), depression (F = 7.52, η² = 0.050), somatization (F = 13.07, η² = 0.082), and hostility (F = 5.28, η² = 0.035) among groups based on sleep duration. These differences remained significant even after controlling for the effects of physical activity, bedtime and daytime napping (all <i>p</i> &lt; 0.01).</p> Conclusion <p>According to the results, insufficient sleep and short sleep duration are significantly associated with elevated anxiety, depression, somatization, and hostility. A key limitation is the reliance on a single self-report item for assessing sleep duration, which is subject to recall bias. Future longitudinal studies with objective sleep measures be conducted to explore the causal links between sleep duration and mental health.</p>