the pilot study involved just 29 people, whittled down from more than 2,000 who had responded to a washington post article published that summer about people whose moods changed with the seasons. eleven of those 29 were treated with “bright white lights.” they sat perched by fluorescent light boxes three hours before dawn and three hours after dusk, and all experienced some anti-depressant effects, rosenthal and his team reported in a 1984 paper that would define a syndrome they named seasonal affective disorder, or sad.
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“when we admitted the first cohort, it was in the summertime, and they were really quite well,” rosenthal, a professor of psychiatry at georgetown university school of medicine said in an interview with the national post this week. “some skeptical people said, ‘well, what will happen if they don’t get depressed? you’ll look pretty stupid. and i thought, well, that’s ok, i’ll take that chance. it’s not such a bad thing to look stupid.” but then, on schedule, the majority became depressed, he said. people went “down” at different times, depending on the degree of their sensitivity to light. “we exposed them to light and it was really quite one of the most exciting things…. it was, in some cases, very transformational.”
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the dominant narrative for decades was that seasonal depression was caused by a lack of environmental light, and if you just gave people light, they got better — “the more light, the better,” rosenthal has said . but multiple attempts are underway to tease out the psychological and biological underpinnings and triggers that may be at play in “this annual, recurrent illness,” said toronto psychiatrist dr. anthony levitt, who, together with dr. raymond lam, co-wrote the first canadian guidelines on the treatment of sad, published in 1999.
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still, sad has become saturated in culture: people can buy light boxes at costco. online retailers sell sad lamps and green and blue glow glasses. a finnish tech company is selling a device that blasts bright light — into the ears.
scientists still don’t fully understand sad, and some have argued that the theory behind it, the idea that major depression can be influenced by the seasons, is more rooted in “folk psychology” than objective data.
still, a canadian study using data from statistics canada surveys collected between 1996 and 2013 , that together included more than half a million canadians, found the proportion of people reporting a major depressive episode in january was 70 per cent higher than in august.
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one study found that, “reminiscent of humans with sad,” male nile grass rats express less sexual interest when interacting with females in dim, winter-like daylight. women appear affected more than men, and rosenthal thinks there’s a distinct biological effect, something to do with the female sex hormone that interacts with the effects of light. for both sexes, motivation can feel clipped off. “if people aren’t operating at their best, they should be treated or they should be helped,” said rosenthal, who argues that lesser degrees of sad should be recognized.
one dutch internet-based, crowdsourcing project involving 5,282 people found that while people generally feel better in spring compared to other seasons, the effect sizes were “small, or very small” and, as far as the seasons did influence moods, it only applied to people who scored high on neuroticism, they said.
in 2016, psychologist steven lobello and megan traffanstedt published a paper in clinical psychological science using data from 34,000 american adults surveyed by phone in 2006. the duo reported that depression was unrelated to latitude or season of the year and concluded that their findings “cast doubt on major depression with seasonal variation as a legitimate psychiatric disorder.”
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many benefit from light therapy, he said. light delivered via daily morning exposure to bright light emitted by a freestanding light box has become the “gold standard” treatment of sad, psychiatrist dr. matthew rudorfer of the u.s. national institute of mental health, said this week during a livestreamed talk on sad . how does light help? rosenthal said the thinking is that it’s happening through the retina. “the retina is being impacted by the extra light, and signals are going back through neural connections to the hypothalamus and various nuclei that are connected to emotional centres in the brain.”
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while “a great deal of fuss” was made over the paper suggesting seasonal affective disorder basically doesn’t exist, “nobody said that everybody gets more depressed in the winter,” rosenthal said.