New research suggests that getting
depressed1 when it's cold and
dreary2(沉闷的) outside may not be as common as is often believed. In a study recently published online in the Journal of Affective
Disorders4, researchers found that neither time of year nor weather conditions influenced depressive symptoms. However, lead author David Kerr of Oregon State University said this study does not
negate5 the existence of clinically diagnosed
seasonal6 affective
disorder3, also known as SAD, but instead shows that people may be
overestimating7 the impact that seasons have on depression in the general population.
"It is clear from prior research that SAD exists," Kerr said. "But our research suggests that what we often think of as the winter
blues8 does not affect people nearly as much as we may think."
Kerr, who is an assistant professor in the School of Psychological Science at OSU, said the majority of studies of seasonal depression ask people to look back on their feelings over time.
"People are really good at remembering certain events and information," he said. "But, unfortunately, we probably can't
accurately9 recall the
timing10 of day-to-day emotions and symptoms across decades of our lives. These research methods are a problem."
So Kerr and his colleagues tried a different approach. They
analyzed11 data from a sample of 556 community participants in Iowa and 206 people in western Oregon. Participants completed self-report measures of depressive symptoms multiple times over a period of years. These data were then compared with local weather conditions, including sunlight
intensity12, during the time participants filled out the reports.
In one study, some 92 percent of Americans reported seasonal changes in mood and behavior, and 27% reported such changes were a problem. Yet the study suggests that people may be overestimating the impact of wintery skies.
"We found a very small effect during the winter months, but it was much more modest than would be expected if seasonal depression were as common as many people think it is," said Columbia University researcher Jeff Shaman, a study co-author and a former OSU
faculty13 member. "We were surprised. With a sample of nearly 800 people and very precise measures of the weather, we expected to see a larger effect."
Kerr believes the public may have
overestimated14 the power of the winter blues for a few reasons. These may include
awareness15 of SAD, the high prevalence of depression in general, and a
legitimate16 dislike of winter weather.
"We may not have as much fun, we can feel cooped up and we may be less active in the winter," Kerr said. "But that's not the same as long-lasting sadness, hopelessness, and problems with appetite and sleep -- real signs of a clinical depression."
According to Kerr, people who believe they have SAD should get help. He said clinical trials show
cognitive17 behavior therapy, antidepressant medication, and light box therapy all can help relieve both depression and SAD.
"Fortunately, there are many effective treatments for depression, whether or not it is seasonal," he said. "Cognitive behavior therapy stands out because it has been shown to keep SAD from returning the next year."