Objective: To investigate the cross sectional association between bedroom nocturnal light exposure and objectively measured sleep parameters in college students, so as to provide evidence for promoting sleep health. Methods: From September to October 2019, a convenience sampling method was used to recruit 365 healthy college students from two universities in Hefei, establishing a cohort. Bedroom nocturnal light exposure was measured at the individual level for two consecutive days using a portable illuminometer (TES-1339R; Taishi Corp, Taiwan, China). Sleep parameters were objectively measured over seven consecutive days using wrist worn accelerometers (ActiGraph GT3X-BT, Pensacola, FL). Multiple linear regression models were employed to examine the association between nocturnal light exposure and sleep parameters. Results: Compared to the low nocturnal light exposure (<3 lx) group, the high exposure (≥3 lx) group exhibited significantly lower sleep efficiency[(93.5± 2.7 )%,(92.2±2.9)%, t =3.93], longer wake after sleep onset (WASO)[(24.7±90.3)(29.2±11.2)min, t =-3.66], higher movement index(11.0±3.6, 12.2± 3.8, t =-2.80), and higher sleep fragmentation index(20.5±6.5,23.0±7.0, t =-3.24) (all P <0.01). After adjusting for covariates,multiple linear regression showed that,compared to the low nocturnal light exposure group, the high exposure group had reduced sleep efficiency ( β =-1.15, 95% CI =-1.78 to -0.52), increased WASO [ β (95% CI )=3.94(1.55- 6.33 )], higher movement index[ β (95% CI )=1.05(0.20-1.89)], and elevated sleep fragmentation index[ β (95% CI )=2.35(0.81-3.88)](all P <0.05). Conclusions Light exposure at night negatively impacts college students sleep. Optimizing bedroom lighting management may improve sleep quality in adolescents.