Why do we get tired? One factor is our body’s internal timing feature, or ‘biologic clock’. Our genes produce proteins that tell our bodies what to do and affect how we feel. For example, the changing levels of certain proteins in our cells over the course of a day and night might be what causes feelings of tiredness or alertness. These proteins are part of our ‘biologic clock,’ telling our body when to sleep and when to wake up. A ‘biologic clock’ is also present in other body systems. Many of our cardiovascular functions, including blood pressure and heart rate, are also influenced by internal ‘biologic clocks.’
MESA researchers have previously shown that individuals with irregular sleep patterns, which disrupt the ‘biologic clock’, are more likely to have metabolic abnormalities, potentially leading to higher future cardiovascular risk. In this paper, we studied about 2,000 MESA participants whose sleep patterns were monitored for 7 days using a device worn on the wrist. Researchers wanted to see if participants who showed irregular sleep patterns during that 7-day period would have any health issues later in life, compared to participants with more regular sleep patterns.
After an average follow-up of 4 years, we found that participants with the biggest night-to-night differences in sleep duration or sleep timing had double the risk of cardiovascular disease compared to those with the most consistent sleep patterns across 7 days. This association was not explained by established cardiovascular risk factors or other sleep-related factors such as average sleep duration. Our results suggest that disturbances of the ‘biologic clock’ and sleep may both lead to the development of adverse cardiovascular events. More research is needed to learn how disruptions of our ‘biologic clocks’ over time may impact our health.