There may be a reason why pimples always manage to find their way to a teenager’s face before a big date or test… stress.

A new study shows that stressed-out teens are twenty-three percent more likely to break out than their less-tense peers.

Researchers from Wake Forest University studied ninety-four teens from Singapore at two different times to measure the effects of stress on their skin. The severity of their acne was measured prior to taking an exam that determines whether they get into college and during summer break. The researchers conducted the study in Singapore to ensure the weather wouldn’t influence their results. There, the moderate temperature varies little from month to month.

Nearly all of the teens had some form of acne, but only certain types of acne got worse when teens were stressed. Acne occurs when an oily substance that exits the skin through pores gets trapped inside. This is the first step in a chain reaction that leads to inflammation and several different types of blemishes, namely blackheads, whiteheads and red, bumpy pimples.

The researchers thought stress might increase the amount of this oily gunk in the skin, but this would have caused more blackheads and whiteheads… and stress didn’t seem to affect these blemishes in teens. Stress was linked to more pimples though, perhaps because it leads to inflammation, the real culprit.

So you may want to take a deep breath and relax. Clearing your mind could also help clear your complexion.