Seasonal affective disorder, or SAD, is usually something that wrecks your mood during the dark, cold months of winter. But for some people, summer is the time they feel the worst. It's called reverse SAD, and neuroscientists are just beginning to understand how it works.
By now you've probably heard of SAD, or seasonal affective disorder. Each winter, some people become a little bit melancholy, perhaps owing to the decrease in daylight hours. But there's a second group of people who become sad in the summer. How does that work?
When I tell my friends that I prefer dark, cold, overcast, and cloudy to the brightly-lit summertime, some of them look at me like I'm crazy. But it turns out that there's a group of people for whom the long winters of Westeros would be a welcome respite from the heat. They might have reverse seasonal affective disorder, which is also referred to as summer-SAD.
The first thing you should know about summer-SAD is that it's woefully understudied as its own unique disorder. Many studies of seasonal changes in mood combine those who have summer and winter blues, making it hard to understand the distinctions between the two. Other scientific efforts to understand mood disorders probably capture some information about patients with summer-SAD, but because it's far less famous than its wintry cousin, fail to classify those patients properly, instead diagnosing them with major depression or anxiety, or perhaps the less severe dysthymia.
But just because summer-SAD is the forgotten child in the family of mood disorders doesn't mean it doesn't have a long history. The first recorded description of it may have been in 1854, when French neurologist Jules Baillarger described a young man who "at the approach of winter, for three years, is seized with great excitation…is very active…spends a lot of money, [but] as spring makes its influence felt…as the temperature rises, his physical and intellectual forces seem to leave him…he ends up totally depressed…and finally makes suicide attempts."
Different Seasons or Different Disorders?
It wasn't until 1987 that psychiatrist Thomas A. Wehr and colleagues formally described the disorder first at an APA convention and then in the American Journal of Psychiatry, as "Seasonal Affective Disorder with Summer Depression and Winter Hypomania." In his paper, Wehr described twelve patients – eight women and four men, all adults – who because depressed in the summer and had either normal mood or manic episodes in the winter. Their depressive periods began in late spring (March through June) and ended in early autumn (August through October).
Strictly speaking, formal descriptions of seasonal affective disorder do not specify the season in which a patient is affected, suggesting that the winter and summer varieties are the same disorders, experienced at different times of the year. But by 1991, Wehr had enough data to suggest that the two forms of SAD might actually be two different disorders. That becomes clear when taking a closer look at the symptoms of the winter and summer types of SAD. What the two have in common are feelings of sadness and anxiety, but that's where the similarities end.
While winter-SAD is associated with oversleeping, those who suffer from summer-SAD tend to experience insomnia. Winter-SAD is associated with a craving for carbohydrates, and with weight gain. Summer-SAD, on the other hand, typically comes with a poor appetite, and weight loss. Those who have the winter blues find themselves withdrawing from social interactions and experiencing a loss of interest in typically enjoyable activities, while those who have summer blues seem to have an increased sex drive.
Given their contrasting symptoms, Wehr began to wonder if summer-SAD had been hiding in plain sight all along. "The opposite types of depression that we observed in winter and summer depressives have been described previously without reference in seasonality. Several investigators have described contrasting syndromes with increasing sleep or decreased sleep, and weight gain or weight loss," he wrote. "The contrasts we found between summer depression and winter depression overlap to varying degrees with contrasts described previously between dichotomous subtypes of depression, such as endogenous and reactive."
Could it be that earlier efforts at understanding the various forms that depression itself could take had unintentionally revealed the distinctions between summer and winter SAD? The idea is at least plausible.
Where Does Summer-SAD Come From?
Most theories regarding the origins of winter blues come from the fact that there are fewer daylight hours in the winter, meaning that people are exposed to less sunlight. The reduced sunlight may in turn disrupt secretion of a hormone called melatonin in the brain, which goes on to make a mess of circadian cycles. Support for that idea comes from the overwhelming success of therapies involving exposure to artificial sources of light, particularly in the morning.
But what about Summer-SAD? Wehr thought that the elevated summertime temperatures might be to blame, but in the late 1980s and early 1990s there was no empirical data to support his supposition. By 2007, that empirical data was still waiting to be collected.
Writing in the Journal of Affective Disorders, psychiatrist Alvaro Guzman lamented, "it has been suggested, although not yet empirically tested, that high temperatures drive seasonal depressive symptoms in summer SAD." But Guzman actually had another hypothesis. He wondered whether summertime allergies could be to blame.
"Aeroallergens," he wrote, "produce inflammation in the respiratory airways, and inflammation triggers depression in vulnerable individuals." Since winter is the one time of year when pollen is absent, he thought that a relationship between mood and the presence of tree pollen could help explain the origins of summer-SAD. "This study found an association between self-reported mood worsening during periods of high pollen counts and greater dispositional seasonality," Guzman concluded. That is, those people who were said they were more likely to have a bad mood when there was lots of pollen in the air were more also likely to suffer from summer-SAD. He further noted that peaks in the amount of tree pollen in the air coincided with the well-known springtime peaks in suicide.
Whether temperature or allergens in the air or something else, summer-SAD seems more resistant to therapy than does winter-SAD. "A person with summer SAD can stay inside, crank up the AC, and darken the room but then go outside into the heat and it's as if they've never been treated," Dr. Norman Rosenthal, a psychiatrist who worked with Wehr on his early studies of summer-SAD told NBC News in 2011.
Like any effort to classify mental phenomena on the basis of their visible symptoms, it's likely that there are multiple origins for summertime sadness. For some people, it could indeed be the triple digit heat. For others, it could be allergies. Still others could, like those who suffer wintertime SAD, might blame their summer-SAD on disruptions to their circadian rhythms.
For the folks who experience a sort of sub-clinical summertime sadness (like myself!), mainly manifesting in increased irritability and sleeplessness, just knowing that there is a real phenomenon, known to science, underlying their seasonal mood shifts may be enough to cope. At least until the gloriousness of winter, cloud cover, rain, and colder temperatures come back around and true happiness returns.