CLOCK and Cognitive impairment: Prior studies also suggest that the down‐regulation of polyunsaturated fatty acids (PUFAs, e.g., docosahexaenoic acid) in the hippocampus may contribute to a cognitive deficit.[24, 45] However, we did not observe any changes in hippocampal PUFAs between Bmal1‐iKO and control mice (Figure S5F, Supporting Information), precluding a possibility that the intestinal clock regulates cognition through PUFAs.