Figure 1.

Time-of-day-dependent patterns of circulating hormone levels variation. Circadian rhythms are driven by oscillations of endocrine factor levels during the day. These variations are important to perform physiological processes at the optimal time of the day. Melatonin induces the resting phase whereas cortisol prepares the body for the activity phase. The other hormones drive modifications of glucose and lipid metabolism, promoting either catabolism with fatty acid oxidation and glycolysis (FGF21, adiponectin, leptin) or anabolism with lipogenesis and glycogenesis (insulin).