Figure 1.

Schematic depicting experimental design. A) Experiment 1: Female rats were tested twice under red light in both estrus and diestrus phases, separated into two cycle sequence groups: estrus first or diestrus first. B) Experiment 2: Female rats were tested twice under white light in both estrus and diestrus phases, separated into two cycle sequence groups: estrus first or diestrus first. C) Female rats were tested twice under red light in either estrus or diestrus phases. D) Male rats were tested twice under either red or white light.