End of Daylight Saving Time Could Be Heart-Wrenching

Oct. 30 -- WEDNESDAY, Oct. 29 (HealthDay News) -- The end of daylight saving time is just about here, and it may pose health problems much more serious than just a lack of rest and increased grumpiness.

Swedish researchers have found a jump in the number of heart attacks following the semi-annual one-hour time changes.

"This was the very first study on this topic and further studies are needed," said Dr. Imre Janszky, of the Karolinska Institute in Stockholm, and co-author of a letter published in the Oct. 30 issue of the New England Journal of Medicine.

"However, we can certainly say that our study adds some further evidence that vulnerable individuals might benefit from avoiding sudden changes in their biological rhythms," Janszky said.

Those vulnerable individuals would include people already sleep deprived, other experts said.

"When somebody has sleep deprivation, obviously that deprivation does affect their health, including the possibility of having heart attack and stroke," said Susan Zafarlotfi, clinical director of the Institute for Sleep-Wake Disorders at Hackensack University Medical Center in New Jersey. "Those patients who do have a higher risk -- such as high cholesterol and, specifically, if they snore -- should be very, very careful with their time to bed and time to rise, not only for the fall back but also across the board."

The end of daylight saving time occurs Sunday, Nov. 2, when clocks are turned back one hour.

"Our circadian rhythm, which is the biological clock within the human body, gets its cues from time and light," Zafarlotfi explained. "This coming Sunday when we go backwards, our bodies are not going to be clocking so quickly, so the clinical consequences would be fatigue, tiredness and a little bit of lack of attention and lack of concentration."

For the new research, the study authors used a registry with information on all heart attacks occurring in Sweden since 1987. Then they compared how many heart attacks happened during each of the first seven days after "spring forward" and "fall back," and the average of how many occurred on the corresponding weekdays two weeks before and two weeks after the day of transition.