Are you not getting enough sleep, or are you getting too much? If your answer to either of these questions is "yes," you may be at risk of heart disease.
Just the right amount of good-quality sleep is key to good heart health, according to researchers at the Center for Cohort Studies at Kangbuk Samsung Hospital and Sungkyunkwan University School of Medicine in Seoul, South Korea. Poor sleep habits may put you at higher risk for early signs of heart disease, even at a relatively young age.
The researchers studied more than 47,000 young and middle-aged men and women, average age around 41, who answered questions about how long and how well they slept.
Then they had tests to measure their cardiovascular health. Early coronary lesions were detected by measuring the amount of calcium in the arteries of the heart. Stiffness of arteries was measured by the speed of blood coursing through the arteries in the upper arm and ankle.
Calcium buildup and arterial stiffness are two important warning signs of oncoming heart disease.
Findings showed that adults who slept fewer than five hours a night had 50 percent more calcium in their coronary arteries than those who slept seven hours. Those who slept nine hours or more a night had even worse outcomes, with 70 percent more coronary calcium compared to those who slept seven hours.
Sleep quality also made a big difference. Adults who reported poor sleep quality also had more calcium buildup in their arteries, 20 percent more than those who said they slept well.
Dr. Yoosoo Chang, co-lead author of the study, says there was a similar pattern when they measured arterial stiffness. The findings suggest that poor sleep quality, too much sleep and too little sleep all play a role in heart health.
The findings of this study are "profound," says Dr. David Meyerson, a Johns Hopkins cardiologist and spokesman for the American Heart Association. "You wouldn't imagine that too little sleep, too much, or not sleeping well is going to influence your blood vessels so quickly or so early in life."
Of course, this study doesn't prove that the sleep problems are causing the heart problems. That's a question that needs a lot more study.
As for why this happens, Meyerson says there are numerous potential factors, including hormones, metabolic factors produced by sleep and chemical changes in the body during sleep that can increase blood pressure. "All of that goes into our overall health," he says, "but we just don't know yet how all the mechanisms really and truly work."
Meyerson says the findings of this study should be a heads-up for health care providers and cardiologists to discuss sleep habits with patients when they evaluate cardiovascular risk and overall health status.
The findings were published in the October issue of the journal Arteriosclerosis, Thrombosis and Vascular Biology.
STEVE INSKEEP, HOST:
Now let's identify a health problem that sensors might someday detect. It's a coronary problem linked to disrupted sleep. NPR's Patti Neighmond reports.
PATTI NEIGHMOND, BYLINE: It boils down to this - seven to eight hours of undisturbed sleep every night is essential for good health.
DAVID MEYERSON: Sleep quality and duration is so important to our physical and emotional well-being.
NEIGHMOND: Cardiologist David Meyerson is spokesperson for the American Heart Association. The study was published in one of its journals.
MEYERSON: You wouldn't imagine that too little sleep, too much sleep or if you're not sleeping well, it's going to influence your blood vessels so quickly and so early in your life.
NEIGHMOND: But it does, according to this new research from Kangbuk Samsung Hospital in South Korea. People who didn't get enough quality sleep or actually got too much sleep increased their risk of clogged blood vessels. Researchers enlisted more than 47,000 young and middle-aged healthy men and women, average age only about 41. They found those who slept less than five hours a night, those who slept more than nine hours a night and those who had restless sleep all showed the beginning stages of blocked arteries.
MEYERSON: They could show calcium beginning to develop in the coronary arteries. They could show that the blood vessels were beginning to get less reactive and stiffer. And both of those issues speak towards development of disease later on.
NEIGHMOND: Why? We really don't know yet, but there are some very likely culprits.
MEYERSON: Hormones, your metabolism, even inflammation is affected by sleep. All of that goes into our overall health, and there are so many factors that we just don't know yet how the mechanisms really and truly work.
NEIGHMOND: People in the study who slept seven to eight hours had no detectable buildup of calcium or stiffness of their arteries. Meyerson says the findings are profound and speak clearly to the need for health care providers and cardiologists to talk with patients about their sleep habits and let them know how very important it is to have an excellent seven to eight hours of sleep every night. Patti Neighmond, NPR News. Transcript provided by NPR, Copyright NPR.