The cold water immersion has four phases. The first one is Cold Shock Response, the second Cold Incapacitation, the third Hypothermia and the last Circum-rescue Collapse or also called post-immersion collapse. Stage 4 (post-immersion collapse) of cold water immersion can occur even after being rescued. During this stage senses are heightened and stress hormones are surged through the body, helping the person survive. After the rescue a mental relaxation occurs. This creates decreased output of the stress hormones. Blood pressure drop and muscles fail, causing collapse.