Irregular sleep is linked to an increased risk of heart disease
Feb. 24, 2023 — Irregular sleep, such as getting an uneven number of nights or falling asleep at different times, may increase the risk of atherosclerosis, or hardening of the arteries, in adults over 45. according to a new study.
Specifically, fluctuations in sleep duration of more than 2 hours during the same week were linked to the development of hardened arteries.
“Poor sleep is associated with a number of cardiovascular conditions, including heart disease, high blood pressure and type 2 diabetes,” says study author Kelsie Full, PhD, assistant professor of medicine at Vanderbilt University Medical Center.
“Overall, we found that participants who slept a variable number of hours during the week (meaning they slept less one night and more one night) were more likely to have atherosclerosis than those who slept about the same amount each night. ” he says.
The findings they appeared inJournal of the American Heart Association.
Atherosclerosis is the accumulation of fatty deposits, called plaques, on the walls of the arteries. This can lead to narrowing of the arteries and reduced blood flow and oxygen supply to the body. The plaque can burst and form a blood clot that blocks the artery, leading to a heart attack or stroke.
To investigate associations with sleep, Full and colleagues examined observational data from more than 2,000 participants in the Multi-Ethnic Study of Atherosclerosis (MESA) sleep supplement study. Adults between the ages of 45 and 84 in six US countries participated in the study Communities: St. Paul, MN; Baltimore City and Baltimore County, MD; Chicago; Forsyth County, NC; Los Angeles County, CA; and Northern Manhattan and Bronx, NY.
Between 2010 and 2013, people in the study wore a wrist device that tracked when they were awake and asleep for 7 consecutive days and kept a 7-day sleep log. An overnight sleep study was also performed to measure sleep disorders related to breathing, sleep stages, and heart rate.
The research team looked at sleep duration, or the total time spent in bed in one night, and sleep time, defined as the time it takes a person to fall asleep each night. The presence of plaque in the arteries was measured by coronary calcium (or calcified plaque build-up in the arteries), carotid plaque (or fatty plaque build-up in the carotid arteries), carotid intima-media thickness (or the thickness of the two inner layers). the carotid arteries), and the ankle-brachial index (or narrow peripheral arteries), all of which indicate the presence of atherosclerosis.
Overall, the average age in the study was 69 years, and 54% were women. About 38% identified as white, 28% as black or African American, 23% as Hispanic American, and 11% as Chinese American.
During the 7-day period, approximately 38% of participants slept more than 90 minutes, and 18% slept more than 120 minutes. Those who slept irregularly were more likely to be nonwhite, current smokers, have lower average annual incomes, shift work or not work, and have a higher average body mass index.
Participants with greater sleep duration irregularity, varying by more than 2 hours per week, were 1.4 times more likely to have a high coronary artery calcium score than those with more regular sleep duration varying by 60 minutes or less. Cervical plaque and abnormal ankle-arm index were also more likely.
Those with irregular sleep timing (that varied by more than 90 minutes in a week) were 1.43 times more likely to have high coronary calcium burden than those with more regular sleep (that varied by 30 minutes or less).
“The biggest surprise to me was that 30% of the study participants’ total sleep time varied by more than 90 minutes during the week,” says Full. “This is consistent with previous studies suggesting that a large proportion of the population has irregular sleep patterns, not just shift workers.”
Further studies are needed to understand the mechanisms, write the authors of the study. Night-to-night variation in sleep duration and sleep timing can cause sleep-wake timing desynchronization and circadian disruption.
“Sleep is a naturally recurring phenomenon, and maintaining regularity helps provide stability and predictability to the body,” says Michael Grandner, PhD, associate professor of psychiatry and director of the Sleep and Health Research Program at the University of Arizona Medical Center.
“When people have very irregular sleep schedules, it can make it difficult for the body to use sleep optimally because it’s a moving target.”
Grandner, who was not involved in this study, has researched sleep disorders and their links to cardiovascular disease, diabetes, obesity and many other adverse outcomes.
“Sleep health is more than getting enough sleep,” she says. “This also means getting quality sleep, at the right time, regularly.”