Off-hand I do not have a good reference (maybe this? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4078443/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4078443

Off-hand I do not have a good reference (maybe this? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4078443/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4078443/ ) but I've heard quite often that both light and food have an impact on our body clocks, and that the systems operate more or less independently. Perhaps someone out there who knows more can clarify.