Setting the clock ahead for daylight savings time may set the scene for a small increase in heart attacks the next day, according to a US study - which suggests that sleep deprivation may be to blame.
Researchers at two hospitals in the US state of Michigan, whose findings appeared in the American Journal of Cardiology, reviewed six years of records and found that they treated an average of 23 heart attacks on the Sunday when the United States switched to daylight savings time. That compared to 13 on a typical Sunday.
"Nowadays, people are looking for how they can reduce their risk of heart disease and other ailments," said Monica Jiddou, the study's lead author and a cardiologist at William Beaumont Hospital in Royal Oak.
"Sleep is something we can potentially control. There are plenty of studies that show sleep can affect a person's health."
A 2008 Swedish report, for instance, found that the chance of a heart attack increased in the first three weekdays after the switch to daylight savings time, and decreased the Monday after the clocks returned to standard time in the autumn.
Jiddou told Reuters Health that her team wanted to see if their respective hospitals experienced the same increase and decrease in heart attacks seen in the Swedish study.