I know, I know—you couldn’t be more delighted that spring and summer are on the way. The toasty days, the warm nights, the gentle breezes and, especially, the lengthening hours of daylight, which begin Mar. 12 with the return of Daylight Saving Time. To which I say: Keep it; keep it all: the heat, the humidity, the hot wind masquerading as a warm breeze. And especially keep all that confounded light. Give me a cloudy sky, a light drizzle, and a 4:30 PM sundown, and I couldn’t be happier.
There’s a whole school of study around the phenomenon of Seasonal Affective Disorder (SAD), the experience of low- and sometimes high-grade depression that strikes about 5% of Americans during the winter months, when days are short and sunlight is scarce. But there’s a smaller, less well-studied group—of which I am a lifetime member—that experiences just the opposite: a summer SAD, also known as reverse SAD, that emerges just as the skies are brightening, the weather is warming, and the days are lengthening. Call us dyspeptics or cranks, but don’t call us crazy, because reverse SAD is at last getting the study it deserves, and more and more researchers are considering it a real and diagnosable condition.
“Some people may be intolerant of the heat, some people may be intolerant of too much light,” says Dr. Norman Rosenthal, clinical professor of psychiatry at Georgetown University and the researcher who coined the term “seasonal affective disorder” in a 1984 paper published in the Archives of General Psychiatry. The reason for summer SAD—which Rosenthal estimates affects about 1% of the U.S. adult population—is not certain, but the condition itself is. “One possibility is that there may simply be an abnormality in circadian rhythms that kicks off summer SAD. At the moment, we just don’t have good data on the neurochemistry of the condition.”
If there is a dearth of research on summer SAD sufferers, there is a wealth when it comes to their wintertime counterparts. For one thing, says Rosenthal, as days get shorter, there is a reduction in levels of the neurotransmitter serotonin in the brain’s hypothalamus, the brain region that regulates mood, sex drive, hunger, sleep, body temperature, and more. Dial down the serotonin, and a whole range of systems can start to come undone.
“There have been studies with drugs that hit a certain serotonin receptor and elicit abnormal responses in winter SAD patients,” says Rosenthal. When those same people are treated with light therapy—essentially bathing in light in the blue-band spectrum—the effect of the drug normalizes. “Some of these people may just be sub-sensitive to natural light,” Rosenthal adds, and need a boost from an artificial source.
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Kelly Rohan, a professor of psychological science at the University of Vermont, reports on a study in which she was involved that found a possible genetic root in wintertime SAD. Working with a sample group of 220 people—130 of whom were winter SAD sufferers—she and her colleagues found an irregularity in a gene that governs melanopsin, a receptor in the retina that influences circadian rhythms, hormone secretions, and cognitive processes, among other things. The irregularity, she stresses, was found in only seven of the SAD sufferers, but the fact that it was there at all suggests that genes may play a role in at least some cases of the condition.
“It’s not going to explain a lot of the variance in terms of who might suffer,” she says, “but there might be something in terms of the melanopsin gene as one example.”
Evolution, too, may play a role. Humans adapted to the dominant light levels in the part of the world they inhabit, and when the days shorten—especially as the extremely brief days surrounding the winter solstice approach—it disrupts the regular balance of mood and bodily functions our systems maintain. Things only get worse in the parts of the world, like the U.S., that set clocks back an hour in the fall, lopping an extra hour of sunlight out of the day.
“We evolved in certain conditions,” says Rosenthal. “We maintain a certain homeostasis [that can be disrupted] by radical changes in the environment.”
But where does this leave the 1% of us who flip the calendar and experience the same internal disruption as light levels increase and the weather brightens? For starters, many scientists believe the key variable may not be too many hours of daylight, but too much heat and humidity during those hours. The neurochemicals dopamine, serotonin, and norepinephrine, which all help shape mood, also play a role in the body’s thermoregulation. Throw too much heat at that system, and brain chemistry can go awry. “It’s possible that people with summer SAD have some abnormalities in some of those key neurotransmitters,” says Rohan.
Melatonin levels may be in play too. A naturally occurring hormone that helps regulate sleep, melatonin is overproduced when light levels are high, says Carolyn Moriarty, a licensed clinical professional counselor at the Chicago Counseling Center. “This can disrupt the sleep-wake cycle,” she explains, and that, in turn, can affect mood.
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One other improbable player in the summer SAD might be pollen. Even in people who don’t suffer severe seasonal allergies, pollen can trigger an inflammatory reaction, which can affect norepinephrine levels. “The inflammatory response crosses the blood-brain barrier and contributes to negative mood states,” says Rohan.
Finally, there may be a host of other factors that have less to do with the body and more to do with the other variables related to summer, says Rohan. People who work seasonally, like teachers, might become depressed—or at least disoriented—as summer approaches and the structure that defines the rest of the year vanishes. Parents face extra childcare burdens when their children are out of school and may also confront financial challenges like paying for summer camp or family vacations. Body image issues can surface as well, as people shed long pants and long sleeves for shorts and bathing suits. Then, too, there is FOMO—or the fear of missing out—as people who love summer post photos of their Memorial Day cookouts and their Fourth of July fireworks parties, and the summer SADders feel like summer losers.
Before diagnosing a clinical case of summer SAD, says Rohan, “it’s really important to rule out the stressors that may be causing a depression.”
For those whose summer sadness is not caused by any of those factors, there are a handful of palliatives. Rosenthal recommends wraparound sunglasses for outdoors and blackout shades in the home as two ways to keep exposure to light levels down. Moriarty suggests spending as much time as possible in air-conditioned spaces—with a bonus if that space is also dark, like a movie theater. And for summer SAD that reaches the level of clinical depression, psychotherapy and psychotropic medications might help as well.
I, for one, will try the glasses and the blackout shades, and I never mind slipping into the cool, dark embrace of a movie theater on a hot August afternoon. But mostly, I’ll just play the waiting game. If long spring and summer days are a seasonal certainty, so too are short fall and winter ones. Enjoy the coming of the light, all you summer lovers, and I’ll meet you on the flip side, when the Earth completes its next half cycle around the sun and the seasons blessedly change again.
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