Sleep and the risk of cardiovascular disease
According to a 2020 study, adults who do not follow a regulat sleep schedule are nearly twice as likely to develop cardiovascular diseases as people with more regular sleep patterns. This study is important, because it is among the largest of its kind in recent years and specifically associates these patterns of irregular sleep with an increased risk for cardiovascular disease.
The study was commissioned by the National Heart, Lung and Blood Institute (NHLBI), which is a global leader in conducting and supporting research on heart disease, lung, blood and sleep disorders and has, as its main objective, improvement the health of the general public. The results of this first prospective study – linking sleep irregularity to BCV development, were published online on March 2 in the Journal of the American College of Cardiology.
A 5-year research suggests that an irregular sleep pattern may be a new and independent risk factor for cardiovascular disease (CVD) and that maintaining regular sleep patterns may help prevent heart disease, as does physical activity, a healthy diet and other lifestyle adjustments.
“Irregular sleep programs appear to be related to some abnormalities in the functioning of the body, including changes in blood sugar and inflammation,” said Michael Twery, a doctor at the National Center for Sleep Disorders Research at the NHLBI.
Previous studies have linked insufficient sleep to a higher risk of obesity, diabetes and heart disease, which is one of the reasons why physicians stress the importance of sleeping for 7-8 hours per night. Although the researchers suspected that the high daily variability of sleep duration and moment may also have negative effects on heart health, its effect remained unclear.
In this study, the researchers followed 1,992 men and women, aged 45-84, who did not have CVD at the beginning of the study. The participants, who were part of the Multi-Ethnic Atherosclerosis Study (MESA), funded by the NHLBI, live in communities across the United States. Of the participants, approximately 38% were white, 28% African-American, 22% Hispanic and 12% Chinese-American. They were followed for about 6 years (2010-2016), with the help of several sleep exams.
To measure sleep regularity, participants wore actigraphic devices on their wrists, which closely monitored sleep and waking for seven consecutive days, including on weekends. The actigraphs look like smart watches and are designed to measure whether a person is active or at rest, that is, whether they are awake or asleep. Also, participants underwent a one-night polysomnography at home at the beginning of the study and a sleep assessment based on a questionnaire.
During 5 years, 111 participants developed CVD, including heart attack and stroke, or even died. The researchers found that participants with the most irregular sleep or synchronization duration were at risk of developing a CVD event in the follow-up period, compared to those with slightly more regular sleep patterns. The correlations remained strong even after adjusting for risk factors, such as obstructive apnea or average sleep duration.
Researchers claim that the biological mechanisms behind sleep irregularity and its link with BCV are still unclear, but they suspect that several factors, including changes in the body’s circadian rhythm (the 24-hour internal clock that controls the sleep-wake cycle) may be involved. Recent studies by the same researchers have correlated irregular sleep patterns with the harmful metabolic changes associated with obesity, diabetes and high cholesterol, and they suspect that similar processes could influence and risk CVD. The purpose of future studies will be to look for blood biomarkers that could help explain this link.
“We hope that our study will help raise awareness about the importance of a regular sleep pattern in improving heart health. It is a new frontier in sleep medicine”, said the study’s lead author, Tianyi Huang, Sc.D,.