Sleep Longer, Help Your Heart

Sleeping an extra hour may do your heart good, a new study
shows.

In the study, every extra hour of sleep was associated with a 33%
drop in participants' odds of developing coronary artery calcification over
five years.

In the long run, that might cut their risk of heart attack or other heart
"events," though longer studies are needed to check on that, the
researchers note in The Journal of the American Medical Association.

About Coronary Artery Calcification

The study is all about tracking new cases of coronary artery calcification
among nearly 500 middle-aged U.S. adults over a five-year period.

The coronary arteries supply oxygen-rich blood to heart muscle. In coronary
artery disease, plaque builds up inside coronary arteries' walls, narrowing the
arteries. Calcium is one of the components of plaque. The more plaque that is
present, the more calcium is present in the walls of heart arteries. So
measuring coronary calcium can be used as a surrogate for measuring plaque.

Sleep Habits

At the beginning of the study, participants got their coronary arteries
scanned using computed tomography (CT) at the beginning and end of the
study.

Participants also wore devices on their wrists for six days at the study's
start to measure their activity, and they provided information on their sleep
habits.

The group averaged about six hours of nightly sleep. Few people slept for
more than eight hours per night, report the University of Chicago's Christopher
Ryan King, and colleagues.

Longer Sleep, Less Calcification

Participants got another coronary artery CT scan at the end of the five-year
study. About 12% had developed coronary artery calcification.

People who slept longer -- as confirmed by their wrist monitors -- were less
likely to have developed coronary artery calcification.

"One hour more of sleep decreased the estimated odds of calcification by
33%," King's team writes.

Those findings take into consideration participants' age, sex, race,
education level, smoking, and sleep apnea risk.

King and colleagues call for further studies to confirm the results, to
learn how sleep duration is linked to coronary artery calcification, and to
figure out exactly how much sleep is best for reducing coronary artery
calcification risk.

By Miranda Hitti
Reviewed by Louise Chang
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