In humans, genetic variation in BMAL1 is robustly associated with neuropsychiatric disorders such as MDD, bipolar disorder (BD), seasonal affective disorder and schizophrenia11 12 as well as cardiometabolic phenotypes including hyperlipidaemia and coronary heart disease.13 14 However, it is unclear whether the same or separate BMAL1 variants predispose mental and physical illnesses, as differences in populations used as well as methods and models applied mean that comparing effects between these studies is not straightforward. This evidence concerns the gene BMAL1 and major depressive disorder.