Irregular Sleep Patterns in Middle Age May Double Heart Risk

Irregular sleep schedules are linked to a significantly increased risk of developing cardiovascular disease, including heart attack and stroke. Research indicates that varying the timing and amount of sleep can impact heart health independently of the total number of hours slept per night.

A study published on March 2, 2020, in the Journal of the American College of Cardiology found that older adults with an irregular sleep schedule had nearly double the risk of developing cardiovascular disease when compared with those who maintained a regular sleep schedule.

Study Methodology and Participant Data

The research was led by Dr. Tianyi Huang at the Brigham and Women’s Hospital. The study received support from the National Center for Advancing Translational Studies (NCATS) and the National Heart, Lung, and Blood Institute (NHLBI), both part of the NIH.

Researchers analyzed data from nearly 2,000 men and women between the ages of 45 and 84. These participants were enrolled in the Multi-Ethnic Study of Atherosclerosis. At the beginning of the study, none of the participants had existing cardiovascular disease.

To establish sleep patterns, participants underwent a comprehensive sleep examination. This process included a questionnaire and an at-home overnight sleep test. Participants wore a wrist-based device called an actigraph for seven days to track their sleep-wake patterns.

The actigraph measured periods of activity and rest to provide an estimate of when participants woke up and went to sleep, as well as the total amount of sleep they received.

Cardiovascular Outcomes and Risk Factors

Over a five-year follow-up period, the study found that participants with the most irregular sleep patterns had more than twice the rate of stroke, heart attack, or death from cardiovascular disease compared to those with the most regular sleep patterns.

The increased risk for irregular sleepers persisted even after the authors of the study adjusted for several variables, including:

• Average sleep duration
• Known cardiovascular risk factors
• Other sleep-related problems, such as obstructive sleep apnea

These findings suggest that the consistency of sleep timing is a distinct risk factor for heart health, separate from the total amount of sleep a person gets.

The Role of Sleep in General Health

Health experts generally recommend that most adults obtain seven to nine hours of quality sleep per night. Quality sleep is necessary to support healthy brain function and critical metabolic processes, such as the control of blood sugar and appetite.

While insufficient sleep has been previously linked to health conditions including diabetes and obesity, the research led by Dr. Huang highlights the specific danger of inconsistent sleep timing.

Further data published on April 6, 2026, indicates that irregular bedtimes double the heart risk specifically for individuals who get fewer than eight hours of sleep.

This suggests that the combination of insufficient sleep duration and irregular timing may further exacerbate the risk of major cardiovascular events.

Future Research Directions

While the correlation between irregular sleep and heart disease is established, the exact biological mechanisms remain under investigation.

Future research will aim to identify the specific biological changes that occur within the body due to irregular sleep schedules to better explain why these patterns increase the risk of cardiac events.