Daylight Savings Linked to Heart Attack Risk


Watch out for the Monday following Daylight Savings Time in the spring, when clocks historically jump ahead and those ruled by the time change lose an hour of sleep.  Traditionally, heart attacks occur most frequently on Mondays, and the switch to Daylight Savings Time has been linked to heart attack occurrences, according to a study led by Dr. Amneet Sandhu of the University of Colorado in Denver.

Sandhu is a cardiology fellow with the university and led the study.  He presented his findings at the American College of Cardiology conference on Saturday, March 29.  His research showed that the Monday that followed Daylight Savings Time saw the risk of heart attack climb by up to 25 percent.  By contrast, heart attack risk fell by 21 percent in the fall when clocks returned to standard time.  It is believed that the risk goes up in the spring because of the stress involved in beginning a new work week and the change that occurs to our sleep-wake rhythms.

During the study, Sandhu looked at 42,000 hospital admissions and saw that on average, 32 patients experienced heart attacks on any given Monday.  However, when that Monday was also the day after the clocks sprang ahead, there were an additional eight heart attacks.  While previous studies have examined the link between heart attacks and lack of sleep, Sandhu admits that experts still struggle to determine exactly why people are sensitive to the sleep-wake cycle and noted that the study suggests that even small changes to the cycle can have seriously detrimental effects.

Sandhu suggested that in understanding which days could see an increased risk of heart attack, doctors can be better prepared for the increase in heart attack risk that Daylight Savings Time seems to bring.  The study, however, was not without its faults; Michigan was the only state involved in the study, which caused some limitations, and certainly, patients who died prior to arrival at the hospital were not incorporated into the study results. In fact, the only database used in the study was that which incorporated information from non-federal Michigan hospitals.  The records were from a comprehensive time frame, however; four years were covered in Sandhu’s report.

Certainly, the inclusion of only Michigan and the death of patients from heart attack had an influence over the overall study outcomes.  Sandhu also acknowledged that the study incorporated those patients who required artery-opening procedures from their heart attacks.

Symptoms of heart attack include chest discomfort that lasts longer than a few minutes and that may feel like squeezing or fullness; shortness of breath; discomfort in the upper body; and lightheadedness, nausea or breaking into a cold sweat.

All of these are potential signals for a heart attack, and Sandhu notes that the information gleaned from the study about the potential for higher risks for a heart attack can go a long way towards helping medical professionals be ready for possible spikes in the numbers of heart attack patients they see on certain days.  While Daylght Savings Time might be linked to a higher risk of heart attack, there are a variety of other factors at play, such as stress levels at starting a new week and a general lack of sleep, that can also increase risk.

By Christina St-Jean



Baltimore Sun

American Heart Association



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