Irregular Sleep Patterns Double the Risk of Cardiovascular Disease in Older Adults

March 4, 2020
Older adults with irregular sleep patterns -- meaning they have no regular bedtime or wake-up schedule -- are nearly twice as likely to develop cardiovascular disease (CVD) as those with more regular sleep patterns, according to a study published in the Journal of the American College of Cardiology. The 5-year study suggests that an irregular sleep pattern may be a novel and independent risk factor for CVD, and that maintaining regular sleep patterns could help prevent heart disease just as physical activity, a healthy diet, and other lifestyle measures do. “We hope that our study will help raise awareness about the potential importance of a regular sleep pattern in improving heart health,” said Tianyi Huang, Brigham and Women’s Hospital, Boston, Massachusetts. “It is a new frontier in sleep medicine.” “Research has linked irregular sleep schedules to a constellation of disease-causing abnormalities in body function, including changes in blood sugar and inflammation,” added Michael Twery, PhD, National Heart, Lung, and Blood Institute, part of the National Institutes of Health, Bethesda, Maryland. “This study is Important because it is among the largest of its kind, and it specifically associates these irregular sleep patterns with an increased risk for cardiovascular disease.” For the current study, researchers followed 1,992 men and women aged 45 to 84 years who did not have CVD at the start of the study. The participants, who were part of the Multi-Ethnic Study of Atherosclerosis (MESA), lived in communities across the United States. Participants wore actigraph devices on their wrists to closely track sleep and wake activity for 7 consecutive days, including weekends. They also underwent a 1-night at-home polysomnography at the beginning of the study and took a questionnaire-based sleep assessment. Of the participants, about 38% were white, 28% African American, 22% Latino, and 12% Chinese American. During the 5-year follow-up period, 111 participants developed CVD events, including myocardial infarction (MI) and stroke, or died from CVD-related causes. The researchers found that participants with the most irregular sleep duration or timing had more than double the risk of developing a CVD event over the follow-up period compared with those with the most regular sleep patterns. The associations remained strong even after adjusting for known cardiovascular risk factors and other sleep variables such as obstructive sleep apnoea and average sleep duration. The association between irregular sleep and CVD appeared stronger among racial/ethnic minority populations, particularly African Americans, than among whites, the researchers said. This finding is consistent with recent studies that show racial minorities tend to have a higher risk of sleep disorders than whites. Although past studies suggest that women are more likely than men to be affected by unhealthy sleep, the current study did not find significant gender differences. The researchers said they are still unclear about the exact biological mechanisms behind the sleep irregularity and CVD link, but they suspect that multiple factors, including harmful disturbances in the body’s circadian rhythm. In future studies, the researchers said they will look for blood biomarkers that may help explain the apparent link. Larger studies with longer follow-up will also be important to confirm these findings. Reference: SOURCE: National Institutes of Health