season of SAD: What we do (and don't) know about winter

As the winter of 1981 neared, most of the subjects in Dr. Norman Rosenthal’s study began feeling physically weighed down and emotionally sluggish, the way he predicted they would.

They craved sweets and chocolates and starch-rich foods, though eating “would not be expressed as pleasurable,” but more of a compulsion. Most had a history of seasonal cycles of depression. Their moods would frequently start plummeting between October and December. They would go to sleep earlier, sleep longer and wake later, their energy crashing in late afternoon. Unmotivated, lethargic and depressed, they would hunger for light like moths drawn to porch lamps.

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“One woman had been nicknamed ‘Lights’ by her husband because of her habit of turning on all the lights in the house on entering it,” Rosenthal and colleagues wrote. People dreamed of sunbathing on beaches. Those who could travel south to Florida or the Caribbean reported improvements in their moods within days of arriving, “and a deterioration in mood a few days after returning North again.”

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.

“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.”

Rosenthal was working at the National Institute of Mental Health In Bethesda at the time. Not all of his colleagues were convinced of the legitimacy of this newly described phenomenon. A lot thought it would prove to be trivial, or worse than trivial — just wrong. “Some made a joke out of it,” Rosenthal said. He remembers a female colleague of his at a conference saying, “Come on, come stand in front of the lights with me. I’m feeling depressed.”

We don’t know what the trigger is, and it may be different for different people

Nearly four decades out, the skepticism hasn’t been entirely eliminated. But when clocks fall back by one hour at 2 a.m. on Nov. 7, ending daylight saving time and forcing a mass societal jet lag, it will also correlate with the onset of seasonal depression, according to those who study the phenomenon. Throw in a second winter of COVID and it could mean darker days than usual. “If you’ve got SAD and COVID anxiety,” Rosenthal said, “it’s just a double whammy.”

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Today, SAD is formally recognized in psychiatry’s official catalogue of mental illness as major depressive disorder with a “seasonal pattern,” a subtype of major depression. 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.

“Certain hormone levels, certain basic building blocks of proteins — these all shift with the seasons,” said Levitt, chief of the Hurvitz Brain Sciences Program at Sunnybrook Health Sciences Centre in Toronto.

But what shifts those critical biological molecules? Is it length of day? Is it amount of light? Temperature, wind velocity or barometric pressure?

“We don’t know what the trigger is, and it may be different for different people,” Levitt said. But SAD is likely the result of some external trigger, combined with a predisposition for depression itself, because of genetics or family history, say, and a person’s “unique psychological response to the seasons,” he said.

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Levitt once had a trainee who refused to put on his winter jacket until well into January. He refused to accept it was winter. More than half the population reports a seasonal change in mood or energy, he said, making it a statistically normal human behaviour. It doesn’t, however, mean the person is necessarily dysfunctional. A lot of people aren’t that great with how dark it gets.

SAD runs the spectrum, Levitt and others said, from the winter blahs (formally known as “subsyndromal SAD”) to full-blown depression that interferes with day-to-day functioning. While 10 per cent of the population, based on questionnaire studies, report SAD or subsyndromal SAD, less than one per cent meets criteria for a “seasonal pattern of major depressive episodes,” said Lam, associate head of the department of psychiatry at the University of British Columbia. The lifetime rate for major depressive episodes in Canada is 12 per cent.

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.

Dr. Norman Rosenthal: “If people aren’t operating at their best, they should be treated or they should be helped.” PHOTO BY COURTESY GEORGETOWN UNIVERSITY

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.

“What makes this unique is that there are very few subtypes of depression that we know when they’re going to come on” — most frequently between November and December, though some in Rosenthal’s study experienced “anticipatory anxiety” as early as July — “and when they’re going to get better,” Levitt said (symptoms typically subside in March).

There are several hypotheses, including that shortened winter days monkey with the body’s internal clock, causing “chrono-biological” disturbances, and that decreased exposure to daylight hours — shorter “photoperiods” — impairs the regulation of serotonin, dopamine and noradrenaline, the three main neurotransmitters scientists think are disturbed in depression. Reduced light exposure also seems to up the night-time secretion of melatonin, the body’s natural sleep hormone. Instead of waking refreshed and rested, people feel limp, exhausted and drained.

Overeating, oversleeping, weight gain and loss of libido are among the symptoms. 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.

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But some have problems with the whole notion of seasonal depression. 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.”

“I don’t think I changed many minds, to be honest with you,” LoBello, a professor of psychology at Auburn University at Montgomery in Alabama said this week. Much of the early literature, he said, didn’t measure true depression. “They were asking people if their mood changed in the winter, and what season of the year you felt worse. That’s a pretty loose sort of way of evaluating mood changes, I thought.” Were people responding in a way that was more culturally conditioned, he wondered? Aren’t we supposed to feel worse in the winter?

LoBello lives in Alabama, but he’s been to places where winters are harsh, like Canada. “It seems to me life gets more difficult for people — getting around, taking on and pulling off bulky clothes,” he said. “But you have to ask yourself, what is SAD, exactly?”

Rosenthal maintains that the data accumulated over the past 30-plus years have built a strong case for the validity of SAD and that it deserves a stand-alone category of its own in psychiatry’s official catalogue of mental disorders. He feels deeply uncomfortable with associating neuroticism with a higher risk of SAD. “It’s an unfortunate term, because it’s got a kind of Freudian feel about it — ‘Oh these people are neurotic, they’re just complaining about nothing.’” People who are already suffering for biological reasons shouldn’t be further stigmatized.

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.”

Other things that help: regular morning walks, looking up at the sky even if it’s cloudy; brief psychotherapy like cognitive behavioural therapy; stress reduction and trying to keep up social activities; and anti-depressants for more severe cases, more melancholic symptoms. What doesn’t work: tanning beds. Light therapy works through the eyes, not the skin. Most light devices have the UV screened out.

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The Canadian guidelines recommended a starting dose of light therapy of 30 minutes per day, preferably in early morning, with a 10,000-lux fluorescent light box. “From a biological clock perspective we know the dawn signal is more important than the dusk,” Lam said. People should sit close enough to the box but avoid staring into the light.

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.

After a splash of publicity, “it just kind of fizzled out. It faded away, because the phenomenon is real.” He’s seen SAD with his own eyes, he said. To Rosenthal, it’s as clear as the light of day.

NOTE – This article was originally published in Nationalpost and can be viewed here