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Turning back clocks good for our hearts?

Turning your clock back on Sunday may be good for your heart.

Swedish researchers looked at 20 years of records and discovered that the number of heart attacks dipped on the Monday after clocks were set back an hour, possibly because people got an extra hour of sleep.

But moving clocks forward in the spring appeared to have the opposite effect. There were more heart attacks during the week after the start of daylight saving time, particularly on the first three days of the week.

“Sleep – through a variety of mechanisms – affects our cardiovascular health,” said Dr. Lori Mosca of preventive New York-Presbyterian Hospital, who was not involved in the research. The findings show that “sleep not only impacts how we feel, but it may also affect whether we develop heart disease or not.”

The study was described in a letter published in today's New England Journal of Medicine by Dr. Imre Janszky of the Karolinska Institute and Dr. Rickard Ljung of Sweden's National Board of Health and Welfare.

In the week after “spring forward,” there was a 5 percent increase in heart attacks, with a 6 percent bump on Monday and Wednesday and a 10 percent increase on Tuesday. In the week after “fall back,” the number was about as usual except on Monday, which had a 5 percent decrease.

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