Objectives: To determine whether sleep quality mediates the relationship between traumatic life events and psychological wellbeing in college students. Methods: 40,646 undergraduate responses from the Spring 2017 National College Health Assessment II were evaluated for relationships between two predictor variables--"satisfactory sleep" and "traumatic life events," and two outcome variables--"psychological distress" (a composite of anxiety, exhaustion, feeling overwhelmed, depression, sadness, loneliness, hopelessness, and anger) and "suicidality" (composite of self-harm behaviors, suicidal ideation, suicide attempts). Linear mediation regression analysis via structural equation modeling was used to test these relationships. Results: Each additional "traumatic life event" students reported experiencing was associated with a 27.6% - 58.9% increase in the odds of reporting indicators of psychological distress or suicidality. "Satisfactory sleep" significantly mediated this negative relationship (proportional effects between 10.6 and 12.5%). Conclusions: Healthy sleep mediates the impact of traumatic life events on psychological distress and suicidality.