Why do people have an increased risk for heart attacks in the morning? Why is asthma more severe at night? Why does meal consumption during the evening hours negatively impact weight loss? Research suggests that these and other tendencies are driven by our circadian rhythms (body clock).
Understanding Circadian Rhythms
Circadian rhythms are biological processes that regulate numerous body functions throughout the day and recur according to roughly a 24-hour cycle. The timing of these processes is controlled by the brain’s central clock, the suprachiasmatic nucleus (located in the hypothalamus), as well as peripheral clocks located in virtually all organs and tissues. Although circadian rhythms are inborn, they adjust according to external cues – especially the presence or absence of light.
Studying Their Impact on Health
Researchers at the Brigham and Women’s Hospital Medical Chronobiology Program study how the circadian system impacts our health. They have shown, for example, that the system signals the body to increase production of a certain protein that promotes blood clotting at about the same time as a person normally wakes up. This may partially account for why we observe more heart attacks, stroke, and sudden cardiac death during the early morning hours.
The research team also has shown that voluntary behaviors that aren’t in sync with our body clock can adversely affect our health and may help explain, for instance, why night shift workers are at increased risk for diabetes, obesity, and cardiovascular disease. This includes its findings that the timing of meals can have a significant impact on weight loss and glucose control.
In the video below, Frank A. J. L. Scheer, PhD, Director of the Medical Chronobiology Program, provides more details about the circadian system’s role in our health.