Figure 2. Circadian rhythm of cardiac metabolism in rodents.

During the light phase, mice are resting, and the predominant processes in the heart are lipolysis, protein synthesis, and autophagy, representing a “remodeling and repair” phase. During the dark phase, mice are active, and the main processes in the heart are glucose uptake, glycolysis and oxidation, glycogenolysis, amino acid catabolism, ROS clearance, etc., representing a “catabolic” phase. The core clock factor BMAL1 reaches peak at ZT0 and nadir at ZT12.