According to results gathered by the Second National Registry of Myocardial Infarction (heart attacks), winter was the top season for heart attacks, followed by fall, then spring, then summer. The December issue of the Harvard Men's Health Watch looks at potential causes for this seasonal trend.

There were 53% more heart attacks in winter than summer. January was the leader with twice as many heart attacks per day than July, the safest month. And winter heart attacks tended to be more serious with a 9% fatality rate. Research suggests that winter heart attacks produce more damage to cardiac muscle than those in any other season.

The Harvard Men's Health Watch suggests a number of factors that contribute to the increased seasonal risk, among them:

-- Cold weather blues

In the cold, blood vessels constrict to help conserve body heat. Narrowed vessels also mean higher blood pressure, which puts additional strain on the heart.

In colder climates, people tend to exercise less when temperatures dip and snow and ice are common. Another weather related problem: snow shoveling. Snow shoveling is heavy exercise that can tax the heart of those who aren't normally active.

Studies show that cholesterol levels peak in the winter months.

-- Holiday happenings

A high-fat holiday meal can interfere with relaxation of the arteries and may also activate the clotting system, which can spell trouble for people with coronary artery disease. Also, excess alcohol intake can increase blood pressure and contribute to heart rhythm abnormalities.

Despite its reputation as joyous time, many people feel depressed or overly stressed during the holiday season. Depression and stress are associated with a higher risk of heart attack.

The Harvard Men's Health Watch reminds men to keep warm and shovel snow with extreme care, or pay someone to do it. Avoid overindulging during the holidays, and reduce stress by seeking comforting social connections during this busy time of year.

The Harvard Men's Health Watch is available from Harvard Health Publications, the publishing division of the Harvard Medical School, for $24 per year. Subscribe at or by calling 1-877-649-9457 toll-free.

Harvard Men\'s Health Watch
Harvard Health Publications
Cambridge, MA 02138
United States
Phone 617-432-4717