Why Irregular Sleep Patterns May Harm Your Heart Health

“Sleep tight, get up right.” We’ve heard it since childhood.

While we’ve heard the benefits of a good night’s sleep many times over, new research is showing that regular sleep patterns — not just duration of sleep — may actually help lower the risk of a heart attack.

A new studyTrusted Source shows that adults with irregular sleep patterns have a higher risk of cardiovascular disease (CVD). Irregular sleep pattern was defined as no regular bedtime or wake up schedule.

The study, conducted by the National Heart, Lung, and Blood Institute, found that an irregular sleep pattern in older adults may be an independent risk factor for CVD.

Over the course of 5 years, researchers followed 1,992 men and women, ages 45–84, who didn’t have CVD at the start of the study. These adults lived all across the United States and were of a wide range of ethnicities.

To measure their sleep irregularity, the patients wore actigraph devices on their wrists, which tracked their sleep and wake activity for 7 consecutive days.

A 5-year follow-up period continued, which showed 111 participants developed CVD episodes. This includes heart attack, stroke, and even death from CVD-related issues.

Sleep and inflammation
It’s already widely accepted that poor sleep habits contribute to other health-related issues, like changes in blood sugar and inflammation.

It’s recommended that the average adult get at least 7 hours of sleep per night, according to the Centers for Disease Control and Prevention (CDC)Trusted Source.

Previous studies have also linked lack of sleep to an increased risk of obesity, diabetes, and heart disease. For example, the Sleep Foundation reports that people (of all ages, weights, and lifestyles) who don’t get enough sleep are at higher risk for cardiovascular disease and coronary heart disease.

The CDC reports that most adults need at least 7 hours of sleep each night in order to maintain a healthy heart, and help prevent type 2 diabetes, high blood pressure, and depression.

But what’s different about this study is that researchers adjusted for irregular sleep patterns, rather than just duration of sleep, and discovered that variability is an important factor in heart health, as well.

“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 to those with the most regular sleep patterns,” according to the study report.

What remains to be seen are the biological mechanisms that link sleep irregularity and CVD.

The researchers suspect multiple factors, like metabolic changes associated with obesity, diabetes, and high cholesterol.

“Anything that affects the body’s circadian rhythm, or sleep cycle, can contribute to inflammation. Abnormalities in sleep lead to more inflammation and construction of our arteries, which can upset the cholesterol plaque in our arteries and lead to a heart attack” said Dr. Guy L. Mintz, director of cardiovascular health and lipidology at Northwell Health’s Sandra Atlas Bass Heart Hospital in New York.

“When patients have sleep abnormalities, there is a reduction in a hormone called leptin. This hormone tells us that we are full and not to eat anymore,” he said. “When leptin levels are low we eat more and exercise less, leading to weight gain, obesity, and ultimately insulin resistance, which is a state of inflammation. This sets up a vicious cycle and increases risk for cardiovascular events.”

Biomarkers for healthy living
That said, there’s still more to be learned.

The researchers have said that in future studies they’ll look for blood biomarkers that may help explain the link.

Longer follow ups are also necessary. This will help people learn how to regulate their sleep patterns.

“As noted in the original article, there are some limitations to the study, such as not a very large sample size and relatively short follow up. Also, one limitation is the authors grouped together several different types of endpoints, such as heart attack, stroke, and other events, and a larger study would have been more definitive,” said Dr. Steven Reisman, director of the New York Cardiac Diagnostic Center.

“A proper sleep pattern and duration may be just as important as medical therapy and represents an additive benefit to medication to reduce the chance of heart attack,” said Mintz.

“Looking at specific biomarkers, including markers of inflammation, variability in hormone levels, and blood pressure that can occur throughout the night will be important,” he added.

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