Red light exposure induces cognitive impairment in non-LPS-treated and LPS-treated mice. (A, B) Treatment schedule. Mice were treated with or without LPS (20 mg/kg), and then were exposed to light for seven days. Non-LPS-treated mice and LPS-treated mice were scheduled for open field and Y maze tests on day 8 and a NORT on day 11. (C) Survival curves (n = 20/group). The survival rate did not differ significantly among the red, green and ambient white light-exposed groups seven days after the administration of LPS (10 or 20 mg/kg). (D–I) Red light exposure impaired spatial learning and memory and induced anxiety-like behavior compared with ambient white light and green light exposure in mice, as evidenced by the reduced frequency of entering the novel arm (D) and the reduced time spent in the novel arm (E) in the Y maze test, the reduced time spent in the center (F) and the reduced freezing time (G) in the open field test, and the reduced time exploring the novel object (H, I) in the NORT. Data are shown as the mean ± SEM (n = 6-8/group). *P < 0.05, **P < 0.01, #P < 0.05, ##P < 0.01.