Quality sleep is essential for health and quality of life, and can impact academic performance. Prior research has shown a reduced sleep time in college students. A relationship has been shown between sleep quality and physical activity (PA), but has not been examined extensively in a college cohort, nor has sedentary behavior been factored in. PURPOSE: To examine the effect of sleep quality on sedentary and PA behavior in college students. METHODS: Eighty-one female (n = 53) and male (n = 28) college students (age = 20.2 ± 1.5 yr; BMI = 25.1 ± 4.7; % body fat = 31.8 ± 10.2) underwent 7-day objective PA and sleep assessment via ActiGraph accelerometer. Poor sleep quality was defined as total sleep time (TST) < 6 hours or sleep efficiency (SE; TST / Total time in bed) <85%. One-way ANOVA was utilized to assess mean differences in PA and sedentary behavior between poor sleep (PS) and normal sleep (NS). RESULTS: Based on weekly averages, 22 subjects had poor sleep quality by TST criteria, and 43 subjects had poor sleep quality by SE criteria. Based on TST, PS resulted in greater number of sedentary bouts per day (20.6 ± 2.8) vs. NS (18.5 ± 3.8, P = 0.02), fewer minutes per sedentary break per day (45.2 ± 9.1 and 53.5 ± 14.5, for PS and NS, respectively, P = 0.02), and greater average sedentary minutes per day (701.4 ± 79.4 and 645.1 ± 106.6 for PS and NS, respectively, P = 0.03). Average moderate-to-vigorous PA minutes (MVPA) did not differ between PS (65.0 ± 30.0) and NS (57.6 ± 23.9, P =0.25), nor did any other PA variable. Based on SE, the PS (65.3 ± 27.2) had greater MVPA minutes compared to NS (53.2 ± 22.7, P = 0.04). No other PA variable differed. There was no difference in body composition between groups when analyzing by TST or SE criteria. CONCLUSION: Poor sleep quality, defined as less than 6 hours of TST, appears to have a greater impact on sedentary behavior than PA behavior in a college student population. When sleep quality is poor, college students experience a greater amount of sedentary behavior, while PA variables did not change. This may be a result of the college lifestyle, where walking on campus to classes and other PA is needed regardless of daytime sleepiness as a result of poor sleep. This is one of the first studies to show a relationship between sleep quality and sedentary time in a college-age population.