In the U.S., the three days in which a person is most likely to have a heart attack are Christmas day, the day after Christmas, and New Year's Day.
For one, the holidays often mean winter's first blast of cold and snow.
Extreme cold constricts blood vessels, forcing the heart to work harder, and snow can mean the added physical strain of shoveling which can cause heart attacks.
But experts say the holiday itself can be bad for your health. People feeling sick around the holidays often put off getting medical attention, and the stress of holiday entertaining or travel can cause people to forget to take medications.