Although similar cardiac phenotypes have been shown in previous reports using whole-body Bmal1 knockout mice [3], our findings strengthen the molecular evidence that Bmal1 in the heart is indeed required to regulate cardiac function because whole-body Bmal1 knockout animals exhibited various phenotypic disorders that may affect cardiac function, such as dampened diurnal rhythm in blood pressure and metabolic disorders [11], [12], [39]. Here, BMAL1 is linked to metabolic disease.