Research Laboratories and Divisions

The severity of many diseases varies across the 24-hour period. For example, heart attacks occur most frequently in the morning a few hours after waking up, temporal lobe epileptic seizures of the brain’s temporal lobe usually occur in the late afternoon or early evening, and asthma is generally worst at night. The goal of the Medical Chronobiology Program at Brigham and Women's Hospital is to understand the biological basis behind these time-variant changes in disease severity. We aim to determine whether or not these changes are caused by the body clock (the endogenous circadian pacemaker) or attributable to behaviors that occur on a regular daily basis, including the sleep/wake cycle. Understanding the biological basis of these changes across the day and night may provide an insight into the underlying cause of the disease and could lead to better therapy (e.g. appropriately timed medication to target specific phases of the body clock or to coincide with specific behaviors that cause vulnerability, such as exercise).

To study these effects, we study both healthy and diseased human volunteers while they live in a laboratory in dim light (to prevent the body clock from being reset) and over a period of 5-14 days, during which we adjust their scheduled behaviors including the sleep/wake cycle. During their stay, volunteers have no knowledge of the time. In this way, we can schedule all behaviors to occur at all phases of the body clock, which allows us to analyze the data for the separate influences from circadian and behavioral factors. In addition, we investigate the interaction between the circadian timing system and therapy in the treatment of, e.g., hypertension and nocturnal asthma.

For more information about the Medical Chronobiology Program, please visit their website.

Plamen Ch. Ivanov, PhD
Kun Hu, PhD
Atul Malhotra, MD
Milena Pavlova, MD