KEGG analysis further revealed that melatonin might upregulate pathways pertinent to butanoate metabolism, synthesis and degradation of ketone bodies and alanine, and aspartate and glutamate metabolism (Fig. 7e and Additional file 1: Fig. S4e), and simultaneously downregulate pathways pertinent to malaria, inflammatory bowel disease, hypertrophic cardiomyopathy, and dilated cardiomyopathy, as well as the TGF-β signaling pathway (Fig. 7f, Additional file 1: Fig. S4f). The gene discussed is TGFB1; the disease is inflammatory bowel disease.