A disruption of normal CRs (e.g., due to constant shift work or genetic disruption of clock mechanism) has been shown to negatively affect an individual's wellbeing, metabolism, physical and cognitive performance and may lead to disease including sleep disorders, obesity, depression, neurodegeneration and cancer as it facilitates tumorigenesis and the establishment of cancer hallmarks (47, 48). Here, CLOCK is linked to obesity due to melanocortin 4 receptor deficiency.