These are not the typical laments about seasonal affective disorder, the mood disorder that usually causes depression when the days grow short and temperatures drop. But actually, “summertime sadness,” as Lana Del Rey put it, is a rarer version of the same illness. While about 5 percent of people are thought to have the winter variety of SAD, about one percent instead feel depressed in the summer months.

The two seasonal variants make their suffers feel similarly low, but they’re otherwise very different. Those who get depressed in wintertime tend to get sluggish and put on weight, but summertime SAD sufferers lose their appetites and grow agitated, as the psychologist Jason Goldman explains:

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.

While winter SAD is thought to be caused by shortened daylight hours throwing off circadian rhythms, its summer cousin is a bit more mysterious. One recent study suggests summertime SAD is caused by allergies, with people reporting worse moods on days the air was thick with pollen.

Another theory is that the intense summer light is just as disruptive as winter’s long, cold nights. People might be staying up later in the summer, suspects Alfred Lewy, a professor of psychiatry at Oregon Health and Science University, thus throwing their body clocks for a loop. He told NBC News that he treats summertime SAD patients by suggesting they get early-morning sun and take melatonin, a hormone that promotes sleep.

It could also be a kind of overdose on whichever season seems to be most prominent in a given area: People in the southern U.S. tend to experience summer SAD more so than those in the north.

And then there’s the simplest explanation: People just can’t stand the heat. Thomas Wehr, a scientist emeritus at the National Institute of Mental Health who first documented SAD, says that when people with warm-weather depression were “wrapped in cooling blankets at night, their temperatures dropped and their symptoms disappeared. As soon as they went outside into the summer heat, their depression returned."

Compounding the biological hypomania is the feeling that one should be happy when days are long and hot and filled with alcoholic popsicles and YOLO. Summertime depression can make one feel like a sort of alternate-universe Grinch, perversely hating on the thing that makes all the other Whos in Whoville burst into joyful song.

People “feel like ‘everyone is happier when the spring rolls around, except for me,’” said Kathryn Klock-Powell, a clinical coordinator at South University in Georgia.

Then again, maybe it’s enough just to know that other people aren’t ecstatic about the scorching temperatures, either. And to take solace in the fact that it is, in fact, possible to make an iced version of a pumpkin spice latte.