The Clock is Ticking
When immersed in water 50 degrees or cooler, it takes around 15 to 20 minutes for your core temperature — the temperature of your internal organs — to start dropping. Your body tries to protect itself by flowing blood to the core, causing numbness in your hands and feet. Your blood thickens as it cools, putting stress on your heart. You are now experiencing hypothermia. When your core temperature drops below 90 degrees you will lose consciousness. Obviously, the sooner help arrives the better.
Here’s what happens to your body in 50-degree water:
0 to 5 Seconds: Gasp reflex. You’ll immediately suck in air or, if your head is submerged, two to three quarts of water.
3 to 5 Minutes: You start to hyperventilate, and your heart rate accelerates. Panic attacks set in.
3 to 30 Minutes: You lose feeling and dexterity in your extremities, hampering your ability to swim.
10 to 30 Minutes: Rising blood pressure causes your kidneys to purge fluids; you have to urinate, which promotes dehydration.
15 to 20 Minutes: Your core temperature starts to cool.
30 Minutes: True hypothermia sets in. You become disoriented and start to hallucinate.