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When you don’t get enough good sleep, the short-term consequences are noticeable – perhaps you’re distracted at work or irritated with loved ones. But in the background, irregular and poor sleep patterns can increase the risk of developing cardiovascular disease, according to a study published this week in the Journal of the American Heart Association.
“This study is one of the first investigations to provide evidence of an association between irregular sleep duration and irregular sleep timing and atherosclerosis,” said lead study author Kelsie Full, an assistant professor of medicine in the department of epidemiology at Vanderbilt University Medical Center in Nashville.
Atherosclerosis is the buildup of plaque in arteries, according to the American Heart Association. This plaque is made up of cholesterol, fats, cellular waste products, calcium and fibrin, a blood clotting agent. As plaque accumulates, blood vessel walls thicken, reducing blood flow and therefore reducing the amount of oxygen and other nutrients reaching the rest of the body. Atherosclerosis can lead to cardiovascular health conditions, including coronary heart disease, angina, heart attack, stroke, and carotid or peripheral artery disease.
Poor sleep — including poor quality, abnormal quantity, and fragmented sleep — has been linked to cardiovascular disease and cardiovascular disease-related death before, but less had been known about the specific associations between sleep regularity and atherosclerosis.
Sleep regularity, defined the new study’s authors, is estimated by variations in sleep duration (how long someone sleeps each night) and sleep timing (the time when someone falls asleep at night) – the fewer variations, the better.
The authors set out to learn more about this relationship by analyzing the sleep of older adults – 69 years old on average – who participated in the Multi-Ethnic Study of Atherosclerosis, a longitudinal cohort study designed to examine the prevalence and progression of and risk factors for heart and vascular diseases. More than 2,000 participants were recruited between 2000 and 2002 from Minnesota, Maryland, Illinois, North Carolina, California, and New York State.
During sleep assessments conducted between 2010 and 2013, participants kept a sleep diary over seven consecutive days and wore a wristwatch that tracked their sleep and wake history. Participants also underwent a home sleep study to measure breathing, sleep stages, night wakings and heart rate.
After the participants’ cardiovascular health was assessed during the same time frame, the researchers found that those with irregular sleep duration – those that ranged from 90 minutes to more than two hours over the course of a week – were about 1.4 times more likely to have high calcium points in the coronary arteries. compared to those with more consistent sleep duration. (This calcium score measures the amount of calcified plaque in arteries; a higher number increases the risk of some cardiovascular conditions.) The former group was also more likely to have carotid plaque and abnormal results from a test that assesses blood vessel stiffness.
“These results suggest that maintaining regular or regular sleep durations, or sleeping close to the same total amount of time each night,” Full said, “may play an important role in preventing cardiovascular disease.”
Since sleep quality and atherosclerosis were measured at the same time, the researchers were unable to assess or prove whether irregular sleep caused the condition – they only found an association between the two.
The findings in the study published on Wednesday may be due to both a direct connection between sleep and the heart, and/or other lifestyle factors.
“People with less sleep or irregular patterns tend to have less healthy patterns in other lifestyles (such as diet and physical activity),” Dr. Donald Lloyd-Jones, chair of the Division of Preventive Medicine at Northwestern University Feinberg School of Medicine in Chicago , said via email. Lloyd-Jones was not involved in the study.
“Sleep is essential for the heart to rest, as this is when heart rate slows and blood pressure normally drops,” he added. “Without the usual rest, the heart and vascular system become stressed over time.”
Whatever interrupts a person’s sleep can lead to changes that affect the heart, said Dr. Andrew Freeman, director of cardiovascular prevention and wellness at National Jewish Health in Denver. Freeman was not involved in the research.
“Interrupted sleep — especially (in) those with sleep apnea — usually releases catecholamines like adrenaline, which can do all kinds of things if it’s a chronic problem,” Freeman said. Sleep disruptions can also be a sign of increased stress or anxiety, he added.
Still, the study’s findings were in participants with no history of cardiovascular disease, so everyone should take heed, Lloyd-Jones said.
“Sleep is important for all of us,” he added. “It’s an important part of Life’s Essential 8 approach to optimizing your cardiovascular health — which can also help prevent cancer, dementia and many other chronic diseases of aging.”
Life’s Essential 8 is the American Heart Association’s checklist for lifelong good health, which also includes eating healthy, being physically active, quitting tobacco, controlling weight, controlling cholesterol, and controlling blood sugar and blood pressure.
The association recommends adults get seven to nine hours of sleep each night, which is more likely if you have good sleep hygiene. It involves going to bed at the same time every night, waking up at the same time every day, avoiding caffeine after late morning, using your bedroom only for sleep and intimacy, avoiding screen use before bed and sleeping in a dark, quiet and cool room .
“I also recommend keeping a notebook next to the bed,” Freeman said. “So when people wake up in the middle of the night, (they should) write down the first thing that comes to mind. It could be that they heard a bird or they had to pee or they had a stressor on their mind. And it can be a focus for when they meditate or do something mindful.”
If you have sleep apnea or persistent sleep problems, seek treatment from a sleep specialist or other clinician.