潛水反射：人體在水下的自我保護機制，有助於減緩心跳、降低焦慮感。
When cold water hits the face, a message is sent to the vagus nerve (迷走神經). The vagus nerve controls the parasympathetic nervous system, connecting the brain to the rest of the body and regulates the heart rate and breathing, among other essential functions. Thus, by activating the diver’s reflex, you are able to reset a hyper-aroused nervous system—your heart rate significantly decreases and an increase in peripheral vascular resistance occurs, leading to a redistribution of blood flow.