3.12.2011

5 ways the time change may impact your health

"It's not really understood why some of these health problems that are published coincide with the time change," said Russell Rosenberg, vice chairman of the National Sleep Foundation. "We don't have studies that show the time change actually causes these problems."

With that in mind, here are five health issues that studies have connected with the loss of an hour that day.

Traffic accidents
An increase in traffic accidents is perhaps the best studied health consequence of the time shift -— even if those studies have yielded conflicting results.

"Sleep loss puts people at much higher risk for motor vehicle accidents," Rosenberg said.

A 1996 study published in the New England Journal of Medicine showed an 8 percent increase in motor vehicle accidents on the Monday following the time change. A 2001 study from Johns Hopkins and Stanford universities also showed an increase on the Monday following the change.

While the time shift may present a problem, it also may provide a benefit: The extra hour of evening daylight in the spring may help prevent pedestrian fatalities. Last November, as the clock shifted back to daylight standard time, the National Highway Traffic Safety Administration warned drivers that, with nightfall occurring earlier in the evening, "adjusting to the new, low-light environment can take time, and that driving while distracted puts everyone -— and especially pedestrians -— at greater risk of death or injury."

Workplace accidents
Workplace accidents may be another side effect of the sleep loss from the one-hour time change. They increase in frequency that Monday.

"Instead of bruising a hand, maybe you crush a hand."

A study Barnes led in 2009 looked at the severity of workplace accidents in miners on the Monday following the time change. The researchers found a 5.7 percent increase in injuries and a 67.6 percent increase in work days lost to injuries. Sleep loss determines the difference between the relatively common near-miss that happens in mining, and a true accident, said Barnes.

Sleep loss
In a culture where we are constantly being told we need more sleep, the start of daylight saving time piles another hour per person onto the national sleep debt.

"We're already a highly sleep-deprived society, " Rosenberg said. Additionally, the shift in the period of daylight can present a challenge in catching up on sleep.

"It does take a little extra time to adjust to this time change, because you don't have the morning light telling your brain it's time to wake up," he said.

Heart attacks
The connection between sleep and heart attacks gained attention following a 2008 Swedish study that showed an increase of about 5 percent in heart attacks on the three weekdays following the spring time shift.

"Sleep and disruption of chronobiological rhythms might be behind the observation."

Heart attacks have been found to be highest on Mondays, so a shift in sleeping patterns may explain that as well, Janszky told MyHealthNewsDaily.
However, there have not been follow-up studies to solidify a connection between heart attacks and the change to daylight saving time.

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