Ready to cold plunge? We dive into the science to see if it's worth it

Mikki Smith lets out a cry as she adjusts to the frigid water. It was her first time with the Puget Sound Plungers in Seattle, Washington. (Mike Kane for NPR)

Your body's first reaction to a plunge in chilly water is the "cold shock" response. Your heart rate jumps. Stress hormones spike. You gasp suddenly, and may hyperventilate.

Your reward if you stay in long enough to endure these initial excruciating moments? You start to shiver.