Krentz is not alone. Scientists estimate that 10 million Americans suffer from seasonal depression and 25 million more develop milder versions. But theres never been definitive proof that treatment with very bright lights makes a difference. After all, its hard to do a double-blind test when the subjects can see for themselves whether or not the light is on. Thats why nobody has ever separated the real effects of light therapy from placebo effects.
Until now. In three separate studies published last month, researchers report not only that light therapy works better than a placebo but that treatment is usually more effective in the early morning than in the evening. In two of the groups, the placebo problem was resolved by telling patients they were comparing light boxes to a new anti-depressant device that emits negatively charged ions . The third used the timing of light therapy as the control.
Why does light therapy work? No one really knows. Our research suggests it has something to do with shifting the bodys internal clock, says psychiatrist Dr. Lewey. The body is programmed to start the day with sunrise, he explains, and this gets later as the days get shorter. But why such subtle shifts make some people depressed and not others is a mystery.
That hasnt stopped thousands of winter depressives from trying to heal themselves. Light boxes for that purpose are available without a doctors prescription. That bothers psychologist Michael Terman of Columbia University. He is worried that the boxes may be tried by patients who suffer from mental illness that cant be treated with light. Terman has developed a questionnaire to help determine whether expert care is needed.
【2009年12月英语六级阅读理解的全真模拟题七】相关文章:
最新
2016-10-18
2016-10-11
2016-10-11
2016-10-08
2016-09-30
2016-09-30