Western science takes a stab at explaining how this ancient Eastern practice relieves stress.

Being a lab rat can be pretty stressful, so it’s sometimes nice to take the edge off with a little acupuncture. But lab rats at Georgetown University Medical Center weren’t getting the spa treatment for therapeutic reasons—they became pincushions for science.

Ladan Eshkevari, an associate professor of nursing at the Georgetown University School of Nursing & Health Studies, and fellow researchers investigated exactly how acupuncture works to reduce stress.

They found that, to a certain extent, acupuncture can actually block the chronic effects of stress.

Though acupuncture has been a part of Eastern medicine for decades, Western medicine hasn’t widely accepted the practice because, until now, there’s been no evidence to show how it works or that “meridians,” a series of interconnected pressure points, really exist in the body.

Still, it’s widely used in the U.S. as a complimentary therapy for everything from allergies to GERD.

Eshkevari and colleagues enlisted the help of lab rats to see how acupuncture affects stress. Specifically, they used electroacupuncture, a type of acupuncture in which an electrical current passes through the acupuncture needles.

Eshkavari, a physiologist, nurse anesthetist, and certified acupuncturist said she chose this method of acupuncture to ensure that all the rats received the same amount of treatment.

Researchers caused the rats stress by exposing them to winter-like temperatures for one hour a day, and then gave them acupuncture right below the knee on the pressure point known as “Zusanli.”

After the stress and treatment, researchers tested the rats’ blood for hormones that help the hypothalamus, pituitary gland, and adrenal gland, also known as the HPA axis. These hormones affect the body’s reaction to stress, mood, emotion, and more.

They also measured blood levels of the peptide NPY, which regulates the “fight or flight” response during stressful events. During these situations, blood flow is directed to your vital organs, such as the brain, heart, and lungs and away from systems not tied to survival.

Rats in control situations—those who received acupuncture somewhere besides their Zusanli—had the same elevated level of stress hormones as animals who received no therapy, researchers said.

“We found that electronic acupuncture blocks the chronic, stress-induced elevations of the HPA axis hormones and the sympathetic NPY pathway,” Eshkevari said in a press release. “Our growing body of evidence points to acupuncture’s protective effect against the stress response.”

The study was published Thursday in the Journal of Endocrinology.