CLOCK and obesity due to melanocortin 4 receptor deficiency: Disruption in the circadian rhythm can cause several health problems, such as hyperphagia, obesity, alterations in the glucose metabolism by mutations in Clock [31], an imbalance in the use of glucose and lipids, predisposing mice to diabetes, by the deletion of Nr1d1 [32], and metabolic syndrome and cardiovascular problems in humans by polymorphisms in the CLOCK gene [33].