Often overcast and prone to a dour haze of drizzling weather, the unrelenting winters of Seattle, Washington have long been a way to gauge a person’s affinity for the sun. As the days grow shorter, complexions lighten and moods sometimes darken. For Steven—who asked that his last name not be used—relocating there at the age of 22 manifested a 13-year struggle with seasonal depression that ended only when he moved to Mexico.
“I didn’t bother looking for [a diagnosis] until maybe eight years in,” he says. “I just figured this is life. My depression cleared up during the sunny months and returned with the clouds.”
Some 30 years after it was first identified by psychiatrist Norman Rosenthal, Seasonal Affective Disorder (SAD), or the diagnosis of depression related to a change in seasons, continues to be an often-misunderstood condition. While there’s obviously correlation between the darker days of the winter months and the onset of depression—one that resolves as spring and summer arrive—researchers are still batting around hypotheses as to what exactly is happening to sufferers.
Jeff Janata, Ph.D., a psychologist and Division Chief of Psychology at UH Cleveland Medical Center, says that SAD is often perceived as dynamic brain activity in response to light. “A common theory is that melatonin, which is a brain chemical that helps us feel sleepy, is triggered by darkness,” he says. “With SAD, the increased exposure to that darkness with the shorter days of winter means we’re producing more melatonin and therefore getting sleepier and more lethargic.”
It’s a reasonable enough explanation—a lack of sunlight may be naturally drugging some of us into sleepiness by throwing our circadian rhythms out of alignment—but melatonin’s influence in the brain doesn’t stop there. “Melatonin is also related to serotonin activity,” Janata says. “And that’s related to mood regulation. So SAD is really a multi-module model in terms of what’s going on.”
Newer research involving birds and small mammals and their responses to changes in daylight has shown that melatonin may also corral the hypothalamus portion of the brain by suppressing the active thyroid hormone that helps balance mood and behavior.
With the brain influenced by light hitting the eyes, SAD can range in severity from mild to severe, can strike people both prone to general depression and those who are not, and may impact up to 10 percent of people in specific regions who report some degree of altered moods based on the season. In some ways, Janata says, it’s a manifestation of hibernation. “It makes some sense with evolutionary theory,” he says. “It used to help with survival if we slowed down in the winter, conserved our resources, gained some weight, and slept a lot.”
The line between lethargy, depression, and the overhanging pall of increasing darkness is often blurry. For Steven, Seattle’s winters brought on a case of confirmed SAD that covered his life in a weighted blanket. “It trapped ‘me’ away for eight months per year, and something else was in control of my life,” he says. “I remember being in the back of my own mind, screaming the words I wanted to speak, struggling to make my body move, and it wouldn’t respond.
“I felt completely isolated from everyone because of this, and I was completely incapable of reaching out. After a few years, I just gave up. I knew that nothing I could do would work, and I just waited until the sun came out and I could feel a little normal again.”
Despite having an external and obvious stimulus in the sun, SAD remains one of the least-understood diagnoses in mental health. “Part of the reason for that is lack of research,” says Richard Catanzaro, M.D., a chairman of psychiatry at Northern Westchester Hospital in New York City. “There’s just not a ton of money being spent on it. It’s not commonly seen on the acute end of psychiatry. Few people are being admitted for it.”
Catanzaro says science isn’t still quite sure whether SAD is genetic, or whether someone moving from a sunnier climate might be predisposed to suffering from it more than someone who has lived their entire life under a gloomy weather regime. “The thing we can say with some degree of accuracy is that it occurs more in northern latitudes as opposed to southern latitudes,” he says. In Florida, SAD might account for one percent of mood disorders. In Alaska, Toronto, or Maine, it’s closer to 10 percent.
Because of the sun exposure factor, popular treatments have often included Vitamin D supplementation—the idea being that decreased sunlight means decreased levels of the vitamin, which can influence mood and well-being. “There’s not what I could call robust research showing it’s curative,” Catanzaro says. “It is related to low mood and can’t hurt, but treatment with light therapy or antidepressants is most effective.”
Light therapy is what most presume it to be: Exposure to artificial light to make up for what the sun isn’t producing. Those suspected of having SAD are typically told to sit in front of a light box for 30 minutes in the morning to prevent melatonin from running wild. Though it’s essentially without side effects, some people opt for medication instead. “People don’t have the quote-unquote time for it,” Catanzaro says. “Me, I’d take the lightbox. But some people need both.”
And some people don’t need either. SAD can sometimes be a label too readily applied, a catch-all for anyone feeling blue as inclement weather arrives. “There are other things that happen in the winter besides lack of sunlight,” Catanzaro says. “People aren’t necessarily as social because it’s cold out. Some people have seasonal work and aren’t as busy. They don’t exercise as much. Some people focus on getting depressed during winter and don’t remember there were two weeks in July when they didn’t get out of bed.”
According to Janata, anyone can benefit from rejecting some of winter’s natural quarantine. “Some people would benefit from taking up winter sports, or just spending more time outdoors. Even curling up under a blanket in front of a fire is a coping strategy.” Activity and light—whether natural or artificial—can stave off or help mitigate the effects of a blighted mood.
Janata also believes the growing field of neuroscience may bring us new and compelling insight into how SAD develops. “Our view of depression will broaden significantly,” he says, and SAD is one of many disorders that will benefit.
In the meantime, those hit hardest by SAD may find themselves taking whatever measures are necessary. For Steven, who had tried light therapy, medication, and even hypnosis with only mixed results, it meant leaving Seattle and not looking back. “I took my savings and moved to Mexico. I’ve been here a few years now and no trace of SAD. Life is normal again. I’m me 100 percent of the time.”