Daylight Saving Time (DST) means our body clocks go out of sync twice a year, and it reduces the time we sleep by around 20 minutes for several weeks after the clocks change—and during that time we are more vulnerable to heart attacks, stroke and even fatal accidents, say researchers from the Vanderbilt University Medical Center.
It deprives us of bright morning light that is needed to properly synchronize our biological clocks and, as a result, raises the risk of health problems usually associated with sleep deprivation.
"People think the one-hour transition is no big deal, that they can get over this in a day, but they don't realize their biological clock is out of sync", said Beth Ann Malow, one of the researchers.
In fact, changing the clocks twice a year interferes with our body clock for eight months, she argues, and causes a "profound impact on the biological clock", which affects alertness and energy levels.
It's an argument to end the practice and keep clocks at standard time and GMT, a view that's being considered by some states. Tennessee has already passed legislation that would keep the state's time permanently on DST, but it requires Congress to mandate the decision.