"The circadian clock does not change to the social change," said chronobiology researcher Till Roenneberg of Ludwig Maximilans University in Munich, Germany. "During the winter, there is a beautiful tracking of dawn in human sleep behavior, which is completely and immediately interrupted when Daylight Saving Time is introduced in March."
Roenneberg, lead researcher for a study of the effects of time shifts, said that humans' biological clocks are stronger than the clocks set by Congress.
"When you change clocks to Daylight Saving Time, you don't change anything related to sun time," Roenneberg said. "This is one of those human arrogances -- that we can do whatever we want as long as we are disciplined. We forget that there is a biological clock that is as old as living organisms, a clock that cannot be fooled. The pure social change of time cannot fool the clock."
Though individuals may see their biological clocks reset, and will get an "extra hour" of sleep or rest over the weekend, researchers say that the stress caused by time changes can be bad for the body.
Researchers in Sweden published a report in 2008 in the New England Journal of Medicine reporting that the number of heart attacks jumps during the period immediately following time changes, and that those vulnerable to sleep deprivation should be extra careful.
"More than 1.5 billion men and women are exposed to the transitions involved in Daylight Saving Time: turning clocks forward by an hour in the spring and backward by an hour in the autumn," wrote Imre Janszky and Rickard Ljung, health and welfare researchers in Sweden. "These transitions can disrupt chronobiologic rhythms and influence the duration and quality of sleep, and the effect lasts for several days after the shifts."
Janszky and Ljung said that sleep deprivation can affect the cardiovascular system, leading the vulnerable to have heart problems in the days following Daylight Saving Time changes. Jeanette Torres. abcnewsradioonline.com
Daylight Saving time: How to Cope with the Loss of an Hour Jeanette Torres. March 11, 2011. abcnewsradioonline.
PHILADELPHIA) -- This weekend, the
clocks spring forward into daylight saving time -- the bittersweet adjustment
that brightens the evenings while wreaking havoc on sleep schedules.
For most
people, the shift is a nuisance. But for some, it provokes weeks of sleep
deprivation that take a heavy toll on mood and productivity, according to Dr.
Phil Gehrman, clinical director of the University of Pennsylvania's Behavioral
Sleep Medicine program.
Since researchers began studying the effects of daylight
saving time in the 1970s, the missing hour has been blamed for spikes in car
accidents and workplace injuries, as well as dips in stock market returns.
"People
think, 'It's only an hour.' But considering that most people aren't
getting enough sleep to begin with, they often underestimate what an hour can
do," Gehrman said.
The results are similar to jet lag. But no one
gets jet lag when they lose an hour traveling one time zone east.
"That's
because there's more light in the morning, and that helps you adjust your body
clock," said Dr. Alfred Lewy, chairman of psychiatry and director of the
Sleep and Mood Disorders Laboratory at Oregon Health and Science University in
Portland, Oregon. "But with daylight saving time, the new light-dark
cycle works against your body clock. The extra light at the end of the day
shifts it the wrong way."
The body clock is a cluster of neurons deep
inside the brain in an area called the hypothalamus. It generates the
circadian rhythm, or sleep-wake cycle, that spans roughly 24 hours. But
it's not precise.
"It needs a signal every day to reset it," Lewy
said.
The reset signal is light, which comes in through the eyes and transmits
signals -- separate from those involved in vision -- that update the
clock. But when the sleep-wake and light-dark cycles don't line up,
people feel out-of-sync, tired and even depressed.
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