Heart attacks are believed to be more common in times of heightened emotions, brought on by things such as sporting events, hurricanes and stock market crashes. Now, add Christmas Eve to that list.

The risk for having a heart attack is 37 percent higher on Christmas Eve, peaking at 10 p.m., according to an analysis of when heart attacks occur. The findings, based on a database of 283,014 heart attacks in Sweden over a 16-year period, are published in BMJ. The researchers tracked the occurrence of heart attacks during holiday periods throughout the year, during major sporting events such as the Olympic Games and soccer's World Cup, as well as on random days of the week.

Risk increased for some holidays - up 12 percent on holiday days during the summer and up 15 percent on Christmas Day. Christmas Eve had the highest increase in risk, whereas New Year's Eve had no increased risk. Neither did sporting events.

Beyond that, heart attacks happened most often in the early morning hours and on Mondays. (For what it's worth, this year, Christmas Eve falls on a Monday.) In the United States, about a million people a year have a heart attack, which occurs when blood flow to the heart becomes blocked, preventing the heart from getting needed oxygen. If blood flow is not restored quickly, the heart muscle begins to die. People who get treatment quickly, usually because someone called 911 right away, are more likely to survive.