Heart attacks increase after Daylight Saving Time starts, study says


Well, we weren't expecting this. Though daylight savings has a nasty habit of inconveniencing us by throwing schedules off and cutting into sleeping time (except when it does the reverse, which we'll always welcome), the relationship between heart attacks and squeezing the most of the day isn't one that seems immediately obvious. However, new research indicates that it's not just a mild inconvenience - daylight savings could very well contribute to increased cardiac risk. 

The study, published online in Open Heart, found that Michigan hospitals attended to an average of 32 heart attack patients every Monday in a three year window - from 2010-2013. A curious pattern emerged: on the Mondays immediately following the start of Daylight Saving Time (when an hour is lost), the average number of heart attack patients went up by around eight. This pattern did not continue throughout the rest of the week, suggesting that the transitional period could create undue stress on already delicate hearts. However, no confirmed causal link emerged. 

"What's interesting is that the total number of heart attacks didn't change the week after Daylight Saving Time," said the study's lead author Dr. Amneet Sandhu, a cardiology fellow at the University of Colorado in Denver, in a press release. "But these events were much more frequent the Monday after the spring time change and then tapered off over the other days of the week. It may mean that people who are already vulnerable to heart disease may be at greater risk right after sudden time changes."

Interestingly, the reverse was found when daylight savings came to an end for any given year, with heart attacks decreasing on the following Monday by 21 percent. Perhaps more intriguing is the relationship of Mondays to heart attacks - daylight savings or not, heart attacks are most prolific on Mondays. 

"Perhaps the reason we see more heart attacks on Monday mornings is a combination of factors, including the stress of starting a new work week and inherent changes in our sleep-wake cycle," said Sandhu. "With Daylight Saving Time, all of this is compounded by one less hour of sleep. If we can identify days when there may be surges in heart attacks, we can be ready to better care for our patients." 

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