Having a stressful day? Pop a handful of pistachios.

A recently completed study by Penn State University researchers found that eating two servings of pistachios per day lowered vascular constriction during stress and improved neural control of the heart.

The test focused on patients with well-controlled Type 2 diabetes who were otherwise healthy, according to a news release.

The researchers, led by Sheila West, a professor of biobehavioral health and nutritional sciences, used a crossover design.

One group of patients received the pistachios for four weeks. Then they switched so the other group received the pistachios for four weeks.

Study: Pistachios help manage stress in diabetes patientsBoth groups ate the same number of calories in the provided meals.

Test diets included a standard heart-healthy plan that included 27 percent fat and 7 percent saturated fat. The other diet included two servings of pistachios—a total of about 3 ounces or 150 nut meats—and comprised 33 percent fat and 7 percent saturated fats.

Half of the nuts were salted, the other half unsalted.

At the end of each four-week diet, the researchers measured blood pressure and total peripheral vascular resistance at rest and during two stress tests.

After the pistachio diet, blood vessels remained more relaxed and open during the stress test.

“We found that systolic blood pressure during sleep was particularly affected by pistachios,” West said in the release. “Average sleep blood pressure was reduced by about 4 points and this would be expected to lower workload on the heart.”

The Fresno, Calif.-American Pistachio Growers helped support the study.