The Surprising Truth About Seasonal Depression
That we’re all sad in winter is a common refrain, but some researchers are questioning the season’s psychological effects.
Since Sunday’s daylight saving, many of us are feeling new excitement for spring after months of being beaten down by a frigid winter. Right? Or at least that’s the prevailing narrative across a large part of the country—that we suffer through the doldrums of winter and the payoff is a glorious lead-up to summer’s main event. The idea of winter as a season full of dark, depressing, cold days that people barely survive seems ever-present in American culture, bolstered by articles on how to beat the “winter blues,” a billion-dollar light-therapy industry, and even a countdown in the Pacific Northwest (where I live) to what we call “The Big Dark.” But some researchers have long interrogated that notion, calling winter’s psychological effects into question and wondering whether we hear so much about how terrible winter is for our psyches that we’ve come to believe it unequivocally.
The term seasonal affective disorder, or rather its catchy acronym SAD, is so popular that it’s used in casual conversation. Steve LoBello, a psychologist and researcher at Auburn University at Montgomery, set out to do his own assessment of the nationwide scale of SAD—annual depression that follows a strict seasonal cycle, typically occurring in fall and winter and receding in spring and summer. LoBello and his team analyzed data from the CDC’s behavioral risk-factor survey, which asks hundreds of thousands of Americans each year about their health and well-being, including a separate screening for depression and anxiety, to see whether major depression rates followed a seasonal trend. “We expected cases to increase in the wintertime and then for that to subside starting in early spring and so forth, and there was nothing like that in the data,” LoBello told me of the study they published in 2016. “It was just flat as a pancake all the way through the year.” They also found no correlation between major depression and the respondent’s latitude (or hours of daylight). A couple of years later, in 2018, LoBello published another paper that found no correlation between even mild depression and the seasons. Still, the idea that we are all more likely to be sad and depressed in winter has dominated, and LoBello argues that that view is more steeped in folklore than science.
SAD was introduced to the psychology world in a 1984 paper that presented an American study of 29 patients. Those patients had volunteered for the study by responding to a newspaper ad, and were prescreened to include only those who had already been diagnosed with a major affective disorder. Most of them had bipolar affective disorder and reported having experienced, over at least two previous winters, depression that receded in the spring or summer. A “seasonal pattern” specifier was soon added to the Diagnostic and Statistical Manual of Mental Disorders chapter on affective disorders, and the criteria for SAD diagnosis was set: A person must experience major depression during a specific season, that depression must go away during another season, and that pattern must repeat for at least two years. Today, an estimated 4 to 6 percent of the U.S. population experiences SAD during the winter months—a smaller percentage of SAD cases are summer-induced—which is in no way commensurate with the casual way so many Americans apply the term to themselves.
As with a lot of psychology research, the question of how seasons affect our brains is complicated, and varies widely. Many studies suggest that there is some connection between the seasons, light exposure, and depressive symptoms for some people. Others challenge these findings, such as a 2008 literature review by a team based in northern Norway that reported that, even in their extreme winter environment, they found “no correlation between depressive symptoms and amount of environmental light.” In Sweden and Britain, too, national health systems have reported that the evidence for light therapy in treating depressive disorders is inconclusive. That isn’t to say no one experiences depressive symptoms in the winter because of the weather, just that a population-wide connection explaining that winter = bad mood is hard to pin down.
What’s certain is that no one’s mood and cognition are affected by the seasons the same way. In fact, while longer, warmer days are commonly thought of as a kind of folk remedy for feeling down, some people who live in climates where the sun always shines report feeling a bit out of sorts by the absence of winter. Kate Sedrowski, a 42-year-old rock climber and writer, grew up in Michigan and went to college in Boston before moving to Los Angeles. “The lack of seasons—particularly winter—just did not feel right to me,” she told me by email. “The chill in the air of winter makes me feel more alive and alert, while summer heat makes me lethargic like a sloth. The shortness of the days in the winter forces me to take advantage of the daylight to get things done before I relax and hibernate when it gets dark.” Sedrowski, who now lives in Golden, Colorado, said she feels the highest energy in the cold, snowy, winter months.
Some folks even discover a different kind of productivity in the winter. Living in Atlanta, Muriel Vega doesn’t experience harsh winters by any means, but she grew up in a tropical country where it was always sunny and warm, and she now finds the cooler, southern winter to be her favorite time of year. Vega likes the break from the heat and the constant social obligations. “Winter is a very special time to stay inside,” the 36-year old product manager told me. The summer tends to be filled with friend hangs, beach days, and park visits, but in the winter she’s able to be productive in other ways, such as spending more time with her family, reading, cleaning her house, and cooking time-intensive recipes.
The question of whether winter actually makes us mentally sluggish is also gaining attention from brain researchers. Timothy Brennen, a University of Oslo psychology professor with a focus on memory and cognition, studies whether seasonal differences produce any changes in cognitive tasks such as memory, attention, or reaction speed. He based his research in Tromsø, Norway; it’s located above the Arctic Circle, and for two months of the year the sun doesn’t rise above its horizon at all, making the city a favorite for this kind of study. “Most tests showed no difference in performance between summer and winter, and, of those that did, four out of five actually suggested a winter advantage,” Brennen wrote in his paper. Even so, many of us frequently attribute sleepiness or a lack of brain productivity to seasonal depression. If we were all truly depressed in winter, Brennen told me, “this would have quite huge effects on society, and it just doesn’t.”
The seasons do affect our lives, Brennen clarified, although a growing body of research shows that major psychological effects such as depression and cognitive slowdown are likely not what most of us are experiencing during winter. Waking up on dark winter mornings can be tougher than waking up in the summer, for instance. “But being groggy when you’re woken up from a deep sleep has nothing to do with depression,” he said. What you may be feeling in those instances are the effects of a disruption to your sleep cycle, or the draw of a cozy, warm bed on a cold morning. We may be uncomfortable in lower temperatures, or feel inconvenienced by hazardous weather such as blizzards, and we may even joke about wanting to hibernate for the entire season. Yet our nervous systems and lives don’t just come to a halt. Some of the busiest travel weekends happen over the winter holidays, and throughout January and February, many people flock to the mountains to ski, snowboard, or sled. Sure, winter can be dark, and navigating it can be a pain, but for the majority of us, the season isn’t necessarily to blame for anything more serious than that.