Despite decades-old knowledge that disease severity and biological responses to environmental, behavioral, and interventional exposures vary greatly across the day and night, the underlying mechanisms, consequences, and opportunities of circadian rhythms and circadian alignment for health have only recently become apparent.

Our Medical Chronobiology Program, in the Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, led by myself and Dr. Jingyi Qian includes studies of questions such as: Why are shift workers at increased risk for diabetes, obesity, cardiovascular disease, and depression? Why are heart attacks more frequent in the morning and is asthma worse at night? What explains individual differences in the detrimental effects of disruption of our circadian system, or body clock? How are neurodegenerative disease and mental disorders linked to circadian and sleep disturbances? How does the timing of food intake and exercise influence our cardiometabolic function and disease risk? And can we use the fundamental understanding gained from such research to develop novel and personalized behavioral, environmental, or pharmacological interventions to improve health? We study these questions using a combination of highly-controlled human experimental study protocols and epidemiologic, genetic, animal and ex vivo models to investigate mechanisms, significance, and treatments.