Entries in Body Clock (2)


Daylight Saving Time Ends This Weekend: Good for You!

Medioimages/Photodisc/Thinkstock(NEW YORK) -- Daylight saving time finally ends this Sunday at 2 a.m. -- remember to set your clocks back one hour when you go to bed Saturday night -- and for many of Americans, that could be a downer.  The day seems to fly by, and it's gets dark outside before most can start thinking about dinner.

But many doctors say the return to standard time -- and the extra hour of sleep you get in the morning -- can be healthy.

"Generally, it is always easier to stay up an hour later than to go to sleep an hour earlier, so most people have relatively little problem setting the clocks back in the fall," said Dr. Steven Feinsilver, director of the Center for Sleep Medicine at Mount Sinai School of Medicine in New York, in an email.  "This is because our basic circadian rhythm (the 'body clock') actually seems to be programmed for a longer than 24 hour day.  It runs a little slow."

"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, the 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 stating 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.

Copyright 2011 ABC News Radio


Daylight Saving Time: How to Cope With the Loss of an Hour

Jupiterimages/Thinkstock(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.

Copyright 2011 ABC News Radio

ABC News Radio