Objective: To explore the prospective association between indoor multi period light at night (LAN) and new onset depressive symptoms among college students, so as to provide a new environmental intervention target for the prevention of depressive symptoms among college students. Methods: In September 2019, 347 college students were recruited from two universities in Hefei, Anhui Province. Indoor LAN exposure was objectively measured by using a portable illuminometer for two consecutive nights. Depressive symptoms were assessed by the Mood and Feelings Questionnaire (MFQ) at baseline and during the 2-year follow-up. Generalized estimating equations and Cox proportional hazards regression models were applied to analyze the associations of LAN exposure with depressive symptom scores and new-onset depressive symptoms. Results: The 2-year cumulative incidence of depressive symptoms was 14.70%. Average light exposure at night increased the risk of new depressive symptoms among college students ( HR =1.08, 95% CI =1.01-1.16, P <0.05). Additionally, compared to the dim LAN group (LANavg <5 lx ), the high LAN group (LANavg ≥ 5 lx) had a higher risk of new-onset depressive symptoms ( HR =2.24, 95% CI =1.12-4.45, P <0.05). One hour and 4 hours of post-bedtime light exposure were significantly positively associated with the risk of new-onset depressive symptoms [ HR (95% CI )=1.02(1.01-1.03), 1.05(1.02-1.08), both P <0.05], while 1 hour and 2 hours of pre-awake light exposure showed no statistically significant association with new-onset depressive symptoms [ HR (95% CI )=1.00(0.97-1.02), 1.00 (0.95-1.04), both P >0.05]. Conclusions Indoor LAN exposure, especially exposure during the post-bedtime period, is significantly associated with an increased risk of new depressive symptoms among college students. Improving the bedroom nighttime light environment may be a simple and economical potential intervention strategy for preventing depressive symptoms in college students.