Too little sleep, or poor-quality sleep, may be linked to early markers of heart disease in asymptomatic healthy adults, a new study from South Korea suggests.
More than 47,000 men and women completed a sleep questionnaire and underwent assessments of coronary artery calcium and plaque as well as brachial-ankle pulse wave velocity (PWV).
Participants' average sleep duration was 6.4 hours per night, and about 84 percent said their sleep quality was "good," according to Dr. Chan-Won Kim of Kangbuk Samsung Hospital of Sungkyunkwan University School of Medicine in Seoul, South Korea and colleagues.
The researchers considered those who got five hours or less per night to be "short" sleepers, and those who got nine or more hours to be "long" sleepers.
Short sleepers had 50% more coronary artery calcium than those who slept for seven hours per night, according to the results in Arteriosclerosis, Thrombosis and Vascular Biology. Long sleepers had 70% more calcium than those who slept seven hours.
Those who reported poor sleep quality also tended to have more coronary calcium and more arterial stiffness.
In a 2013 study, people who tended to get less than six hours of sleep nightly were more likely to have high blood pressure, high cholesterol, diabetes and to be obese.
"Adults with poor sleep quality have stiffer arteries than those who sleep seven hours a day or had good sleep quality," co-lead author Dr. Yoosoo Chang of the Center for Cohort Studies at Kangbuk Samsung Hospital said in a statement accompanying the study. "Overall, we saw the lowest levels of vascular disease in adults sleeping seven hours a day and reporting good sleep quality."
Short sleepers were more likely than others to be older, have depression, type 2 diabetes or to be smokers.
"The associations of too short or too long sleep duration and of poor sleep quality with early indicators of heart disease, such as coronary calcium and arterial stiffness, provides strong support to the increasing body of evidence that links inadequate sleep with an increased risk of heart attacks," Kim said by email.
"It is still not clear if inadequate sleep is the cause or the consequence of ill health," but good sleep hygiene, including avoiding electronic media at bedtime, should be part of a healthy lifestyle, Kim said.
"For doctors, it can be helpful to evaluate sleep duration and sleep quality when assessing the health status of their patients," Kim said.
