Untapped potential of circadian rhythms in reducing the burden of disease

Daily rhythms in behavior, physiology, and metabolism are integral part of homeostasis. These rhythms emerge from interactions among endogenous circadian clocks, ambient light-dark-, sleep-activity- and eating-fasting cycles. Nearly the entire primate genome shows daily rhythms in expression in a tissue- and locus-specific manner. These molecular rhythms modulate several key aspects of cellular and tissue function with profound implications in public health, disease prevention, and disease management. In modern societies light at night disrupts circadian rhythm and enables further disruption of sleep and eating-fasting cycle. While acute circadian disruption may cause transient discomfort or flareup of chronic diseases, chronic circadian disruption can enhance risks for numerous diseases. Molecular understanding of circadian rhythm is opening new frontiers through behavioral interventions, timing of drug administration and pharmacological targeting of circadian clock components to prevent or treat diseases. Sleep-extension among short sleepers or restricting eating window through time-restricted eating among people with erratic eating patterns is emerging as non-pharmacological interventions to improve health. Optimal timing of drug administration can reduce adverse side effects or improve efficacy. Finally, small molecule agonists or antagonists of circadian clock components are showing efficacy against a range of diseases from metabolic syndrome to cancer in pre-clinical studies.