We are running elevated zero maze behavior and we are deciding between red light or dim light (for reference, our rats have lights on at 0700h so we typically run behavior during the start of light phase). With other behaviors we have used dim light (for open field for instance) or red light (for elevated plus). We ran a quick pilot to see the difference for the elevated zero, and saw (with a small and variable n) that they spent less time in the open areas under dim light than red light. HOWEVER - we also want to collect CORT samples afterward...and given the fact that CORT is easily changed, we are curious whether anyone believes that running under red v. dim light would impact CORT (if they were exposed for max 15min of light change during their lights on part of the day). I am certainly no circadian rhythm expert, but I would like to think that a short exposure to a red light during their light phase wouldn't significantly impact CORT levels (even though circadian CORT has been shown to peak at the start of the dark phase).

Any thoughts on this or suggestions would be greatly appreciated!!

Thank you in advance for your help!