A new study published March 30 in the journal Open Heart confirms that Daylight Savings Time, when people spring forward by setting their clocks ahead by one hour, not only forces people to wake up an hour earlier, but also increases their chance for suffering a heart attack.
Researchers studied data from Michigan hospitals from 2010 to 2013 and found that on any given Monday, an average of 32 heart attack patients were admitted to the hospital, but on the Monday immediately after the beginning of Daylight Savings Time, an average of 8 more heart attack patients were admitted for a 25 percent increase.
Additionally, the research team discovered that when Daylight Savings Time ended in November, and clocks were reset an hour earlier, there was a 21 percent decrease in heart attack patients being admitted to the hospital on the Tuesday immediately after the fall time change.
These results of the study were presented Saturday at the annual meeting for the American College of Cardiology (ACC) in Washington, D.C.
"What's interesting is that the total number of heart attacks didn't change the week after Daylight Saving Time," said lead study author Dr. Amneet Sandhu, a cardiology fellow at the University of Colorado in Denver.
"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," he added.
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. But Dr. Sandhu has a theory.
"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," he said.
"With Daylight Saving Time, all of this is compounded by one less hour of sleep."