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Daylight Savings Time linked to increase in heart attacks

Teresa Tanoos's picture
Risk for heart attack highest on Monday following spring time change.

Earlier this month, most of the country switched to Daylight Savings Time by springing forward and setting their clocks one hour earlier – and, now, a new study suggests that this time change not only forces people to wake up earlier, but it may also boost their risk of having a heart attack.

For the study, researchers analyzed data from Michigan hospitals between 2010 and 2013. As a result, they discovered that on any given Monday, an average of 32 patients were admitted to the hospital for heart attacks.

However, they also found that 25 percent more heart attack patients were admitted on the Monday immediately following the start of Daylight Saving Time, for an average of 8 more patients on that particular Monday compared to the average of 32 on any other given Monday.

Interestingly, when it was time to “fall back” and reset clocks an hour later in November when Daylight Savings Time ends, the study showed a 21 percent decrease in the admission of heart attack patients on the Tuesday following the fall time change.

These findings were published March 30 in the journal Open Heart and presented Saturday at the annual meeting for the American College of Cardiology (ACC) in Washington, D.C.

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According to an ACC news release, lead study author Dr. Amneet Sandhu, a cardiology fellow at the University of Colorado, found it interesting that the total number of heart attacks tapered off during the week following the start of Daylight Savings Time, although that number spiked at the beginning of the week on the Monday immediately after the spring time change.

Dr. Sandhu explained that this may be due to some people already being “vulnerable to heart disease”, which could put them at greater risk for a heart attack immediately after a sudden time change.

Although the study found a link between the start of Daylight Savings Time and an increase in the number of heart attack patients admitted to hospitals immediately thereafter, the research team was unable to prove a cause-and-effect.

While the researchers pointed out that heart attacks are most common on Monday’s, what remains uncertain is why, but they have a theory that Dr. Sandhu explained has to do with a combination of factors that includes the stress of beginning a new work week and how our bodies are affected by changes to our sleep-wake cycle.

Just getting an hour less of sleep can throw off the body such that it may be time to plan for these adjustments. At least that’s what Dr. Sandhu suggested when he said that regardless of the reasons, the findings of this new study may indicate a need to better staff hospitals on the Monday following the start of Daylight Savings Time.

He added that if we can identify days when surges in heart attacks are more likely, “we can be ready to better care for our patients."

SOURCE: Open Heart, Daylight savings time and myocardial infarction, Amneet Sandhu, et al. Published March 30, 2014 (doi:10.1136/openhrt-2013-000019)