Intense light enhanced the metabolism and maintained the barrier function of the endothelium via increased HIF1A (hypoxia-inducible factor 1-alpha) transcription.36 These protective effects of Per2 on infarction and ECs have also been demonstrated in hindlimb ischemia models.128,129 Here, Per2 mutation or deficiency promoted EC senescence128 and suppressed neovascularization by inhibiting endothelial progenitor cell mobilization.128,129 Together, these data suggest that light modulates heart function and may provide possible therapeutic avenues in the future. Here, PER2 is linked to infarction.