In animals without a functional circadian clock, metabolism becomes abnormal, leading to obesity, diabetes, and cardiovascular diseases.

“So what we have seen is when we, in experimental animals, if they don't have a clock, then their metabolism goes really weird. So just like I said, a metabolism works like this traffic signal in downtown, and if they're not timed properly, then there'll be disease. Similarly, for very long time we knew in the field that mice that don't have circadian clock because they lack a gene or have a mutation, they have various metabolic defect. They have obesity, diabetes, cardiovascular diseases, etc.”