Study Casts Doubt on Whether Seasonal Affective Disorder Is Real

Though American psychiatrists now recognize Seasonal Affective Disorder (SAD) as a subset of depression, it’s a fairly recent condition in medical history. The condition was first defined in 1984, and it’s still not accepted by all scientists. A new study in the journal Clinical Psychological Science suggests that while winter may be a literally dark time, it’s not an emotionally dark one.

Researchers from Auburn University at Montgomery asked 34,300 people of various ages to complete a questionnaire about their depression, where they lived, and other factors. Though a lack of sunlight is often cited as one of the reasons behind SAD (and is the reason people use those bright lamps to beat the winter blues, at least in theory), they found that overall depression levels did not fluctuate with the seasons or with changes in sunlight. People who lived at higher latitudes, who would see less sun during the winter, weren’t any more depressed than people who lived in the south.

“Merely being depressed during winter is not evidence that one is depressed because of winter,” the researchers write. “In clinical cases of recurrent depression, stressful life events associated with episodes may coincidentally co-occur with seasonal changes for some people.” It’s also possible that SAD exists, but at such low rates that this population sample didn’t reveal it.

"The idea of seasonal depression may be strongly rooted in folk psychology, but it is not supported by objective data," they conclude. "Consideration should be given to discontinuing seasonal variation as a diagnostic modifier of major depression."

Research on the Arctic town of Tromsø, Norway, where it’s dark for months at a time, indicates that wintertime woes could be about attitude. There, most residents don’t just ride out the winter; they actively enjoy it, emphasizing its coziness rather than its darkness.

However, that’s not to say your brain doesn’t change from season to season. Another new study, this one in PNAS, found that cognitive function varied throughout the year for 28 volunteers who underwent fMRI testing. However, the researchers found that this change in brain responses wasn’t related to the participants' self-reported moods.