Precious shuteye isn't all that's affected when clocks jump forward one hour each spring and backward one hour each fall. Changes in daylight savings time can also significantly impact your risk of suffering a heart attack, researchers have found.
Adults are more likely to experience a myocardial infarction, or heart attack, during the first three weekdays after the spring shift to daylight savings time, according to a Swedish study published in the New England Journal of Medicine on Wednesday.
The risk of heart attack is nearly 2 per cent higher on the Monday, Tuesday and Wednesday immediately following the spring changeover, which typically sees adults lose an hour or so of beauty rest.
On the Monday after the clocks are pushed back each fall, however, the relative risk of heart attack goes down by as much as 0.985 per cent.
That extra hour of sleep in the fall could have a protective effect on the heart, suggest researchers from the Karolinska Institute and Rickard Ljung of the National Board of Health and Welfare in Stockholm.
"The earlier wake-up times on the first workday of the week and the consequent minor sleep deprivation can be hypothesized to have an adverse cardiovascular effect on some people. This effect would be less pronounced with the transition out of daylight saving time, since it allows for additional sleep," they wrote in a letter to the New England Journal of Medicine.
The study also found the risk of heart attack was more severe in women than in men during the spring transition to daylight saving time. Furthermore, men tend to benefit more than their female counterparts from the additional hour of sleep in the fall.
The increase in risk observed in spring and decrease in risk observed in fall were more pronounced in people under the age of 65. This may be because younger adults have a more taxing daily routine than the average retired senior citizen, the scientists hypothesized.
More than 1.5 billion men and women around the world are exposed to twice annual transitions of daylight saving time.
People with a history of heart disease might benefit from avoiding sudden changes in their sleeping patterns, the researchers suggested.
The average number of hours a Westerners sleeps each night went down from 9 hours to just 7.5 hours over the course of the 20th and 21st centuries, according to sources cited by the study.
The study looked at data collected from the Swedish registry of acute myocardial infarction, with records dating back to 1987. To calculate the risks associated with daylight savings time, scientists compared incidences of heart attack during the first seven days after the spring and autumn transition and the average number of heart attacks on the corresponding weekdays two weeks before and two weeks after.
