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Health effects of daylight-savings time ... Be optimistic
Scripps Howard News Service


October 30, 2007
Tuesday AM

Those extra days of daylight-saving time that Americans are enjoying until the first weekend in November may just be extending a rough time for our bodies' internal daily rhythms, a new study suggests.

German scientists did two studies, one a survey of 55,000 people in central Europe and a second that analyzed the timing of sleep and activity among 50 people as they went through two daylight-saving-time transitions.

The first study confirmed that springing forward represents a significant seasonal disruption to the body clock. Most people in the survey said when they had a free day, they snoozed and woke according to standard time, with some seasonal adjustment for daylight, not DST.

In the smaller study, which followed a group that included both morning people and night owls, the researchers found that the timing of both sleep and peak activity levels quickly snap back when daylight saving time ends, but does not adjust to the start of DST in the spring, particularly among those who like to stay up late and sleep in.

Researcher Till Roenneberger from Ludwig-Maximilian University in Munich headed the studies published online Monday by the journal Current Biology. He said that while people often dismiss the time changes as "only an hour," the research shows that many people never adjust their biological timing for the lost hour of sleep all through the summer and fall.

About 1.6 billion people around the world have to spring forward and fall back each year.

"It's too early to say whether DST has any serious long-term impact on health," Roenneberger said. "But our results indicate that we should consider this seriously."


Another study, this one relying on the brain imaging of a small group of subjects, has identified the brain regions that are activated by optimism. The findings were published online Wednesday by the journal Nature.

It turns out that we use the same part of the brain to look on the sunny side that also shows irregularities in people suffering from depression.

The researchers, led by Elizabeth Phelps at New York University, did functional magnetic resonance imaging of the brains of 15 volunteers, ages 18 to 36, while they thought of possible future life events, such as winning an award or the end of a romantic relationship.

When they imagined positive future events relative to negative ones, the scans detected enhanced activity in areas called the rostral anterior cingulated and the amygdala, the same brain areas that seem to malfunction during depression. All the functions of these regions are uncertain, but lots of earlier research suggests there's some regulation of emotion and decision-making involved.

The NYU researchers noted that, in general, the seven men and eight women in the study were more likely to expect positive events to happen in the near future than negative events, and to imagine them with greater vividness.

Phelps, a professor of psychology and neural science, said the results indicate that while it's difficult to change our outlook on the past, "the future is open to interpretation, allowing people to distance themselves from possible negative events and move closer toward positive ones."

Understanding the basis for optimism is important, because a positive outlook has been related to both physical and mental health, while a pessimistic view matches up with the severity of depression, Phelps explained.


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Stories In The News
Ketchikan, Alaska