What is the diving reflex?

The diving reflex is a physiological response activated when the body is submerged in cold water. It involves two primary components of the nervous system: the sympathetic nervous system, which increases heart rate and releases stress hormones like norepinephrine, and the parasympathetic nervous system, which is triggered specifically when the face is submerged, leading to a calming and relaxation response.

This reflex helps to conserve oxygen and slow down the heart rate, functioning as a survival mechanism by reducing the body's oxygen consumption. This response is not only activated by full submersion; even partial submersion up to the neck can initiate it. The diving reflex is vital for preserving bodily functions by slowing oxygen consumption to prevent rapid hypothermia and maintain mental balance 1.