This Is the Day or Month You’re Most Likely to Have a Heart Attack

Syda Productions/shutterstockMonday is traditionally the most miserable day of the week—so much so that we’ve had to round up inspirational quotes to get through those cranky mornings. It should come as no surprise then that Monday is the day of the week we’re most likely to have a heart attack, according to a Swedish registry study of 156,000 people.

Researchers from Uppsala University and Umeå University analyzed high-quality data from Swedish hospitals on over 156,000 myocardial infarctions (heart attacks) registered in the national quality registry SWEDEHEART over a period of eight years (2006–2013).

According to the study, published in the American Heart Journal, certain time periods on the calendar that are classically linked to stress in society are associated with the incidence rate of heart attack. Compared to control days, the daily incidence rate of myocardial infarction (MI) was higher during the winter holidays and on Mondays, with lower rates on weekends and during summer vacation in July. Which makes sense: Most of us would agree that we’re less stressed during those chilled out sunny weekends. (Have you tried this habit to reduce your risk of stress?)

There are likely a number of reasons for the variations in MI rates, according to John Wallert, PhD student and first author of the article, but stress is clearly one of the more leading culprits. “It is now more probable that stress explains a substantial portion of the fluctuation over time in population MI rates than it was before our study,” Wallert told Eurekalert. Other factors, such as temperature, also appear to influence MI rate changes. These are the silent signs stress is making you sick.

“Our study seems to suggest that psychosocial demands on behavior influence basal biological systems, even to such an extent that they may be potential triggers for MI,” Wallert explains. “When controlling for national data on temperature, air pollution, and abroad traveling by air, the associations of calendar periods with MI rates are surprisingly robust.” Wallert cautions that because this is an observational study, the conclusions are not definitive and that more research is needed.

These findings build on previous studies suggesting that highly stressful events, such as earthquakes and World Cup soccer games, may trigger myocardial infarction. But you don’t have to get caught in a natural disaster or watch an exciting game to trigger heart trouble—those start-of-the-working-week blues many of us experience on Monday morning could be just as impactful.

Don’t quit your job just yet, though. “To scrap the work-week routine would probably be way too drastic,” says Wallert. “How we in society have agreed on periods of work and rest is actually quite well aligned with our predisposed, internal biological clock, the circadian rhythm. However, the alignment is not perfect. For instance, our internal clock is highly unlikely to be aware if today is a Monday or a Sunday.”

Follow these tips to reduce the risk of heart disease—any day of the week.