Summer is the ultimate season for banishing all that pent-up stress from a much-too-long winter, right? After all, just imagining sunshine and the resulting vitamin D overload—not to mention the outdoor activities and the cute, vibrant athleisure that accompany this chunk of the year—can put your mind at ease. But according to new research, the season isn’t as fun and free-spirited as previously thought. In fact, it actually might be more stressful than wintertime.

In the study—which was presented at the conference Experimental Biology in San Diego on April 25—researchers from Poland found that women had higher levels of cortisol—AKA the “stress hormone,” which floods the bloodstream in tense situations—in summer than they did in winter. The scientists analyzed a group of female medical students by collecting saliva samples every two hours for a full 24-hour cycle on two separate days in the winter as well as on two separate days in the summer. They measured cortisol levels and inflammation markers in the samples, and participants completed a lifestyle questionnaire that asked about their sleep schedule, diet, and physical activity.

While winter was hypothesized to be the more stressful season, the participants’ cortisol levels were highest during the summer dates.

While winter was hypothesized to be the more stressful season, the participants’ cortisol levels were highest during the summer dates, with no real change in inflammation levels. “We of course see seasonality in animals, but more and more results show that seasonality is also connected with human beings,” lead study author Dominika Kanikowska, MD, PhD, told the New York Post.

Right now, researchers aren’t sure why the results are so opposite of what was expected (maybe hygge really is helping folks focus on self-care during the cold months). But until scientists have additional intel, consider it all the more reason to relax extra hard come summertime—and maybe even sign up for a mind-body wellness retreat. It is for your health, you know.

Here’s how using scent to bring back vacay memories can be the key to stress-free days. Or, find out how airlines are finally making flying less stressful.