Daylight saving time impacts timing of heart attacks

Heart attacks rise the Monday after setting clocks ahead one hour


Heart attacks occur most often on Monday mornings, but research shows a 25 percent jump in the number of heart attacks occurring the Monday after we spring forward for daylight saving time, compared to other Mondays during the year.

It seems the hour of lost sleep during daylight saving time may play a bigger, perhaps more dangerous role in our body’s natural rhythm than we think, according to a study led by the University of Michigan Frankel Cardiovascular Center.

Although researchers cannot say what might be driving the shift in heart attack timing after the start of daylight saving time, they have a theory.

Perhaps the reason more heart attacks occur 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. Previous studies have linked lack of sleep with heart disease. With daylight saving time, all of this is compounded by one less hour of sleep.

The hospitals included in the study admitted an average of 32 patients having a heart attack on any given Monday. But on the Monday immediately after springing ahead there were, on average, an additional eight heart attacks. Cardiac events tapered off over the other days of the week.

The findings may indicate a need to better staff hospitals the Monday after setting our clocks forward. It may also mean people who are already vulnerable to heart disease may be at greater risk right after sudden time changes.

Turning back your heart risk

“Most heart attacks happen in those who smoke or have risk factors that are not controlled,” says University of Michigan cardiologist Hitinder Gurm, M.D.Quitting smoking would be the most effective strategy for heart attack prevention. Controlling high blood pressure and high cholesterol, following a heart healthy diet and getting regular exercise are other ways to reduce your risk of a heart attack.”

There are limitations to the study. For example, it was restricted to one state and heart attacks requiring treatment such as angioplasty, therefore excluding patients who died before they got to the hospital or received help.

Researchers found a 21 percent drop in the number of heart attacks on the Tuesday after returning to standard time in the fall when we gain an hour back.

The debate continues about whether daylight saving time is actually needed anymore. Widely implemented during World War I, it was primarily adopted to save energy. But some experts question whether it really saves energy and if it has negative health effects beyond just leaving us feeling groggy and out of sorts.

Take the next steps:

Frankel-informal-vertical-sigThe University of Michigan Samuel and Jean Frankel Cardiovascular Center is a top-ranked heart and heart surgery program among Michigan hospitals. To learn more, visit our website at umcvc.org.