Charles W. Bryant,

HOW STUFF WORKS, Maybe you're an adventure traveler trekking the Sahara on foot. Perhaps an ocean storm has left you shipwrecked on a deserted island in the middle of the summer. Or maybe you're just overexerting yourself with yard work and ignoring the signs to slow down and cool off. There are plenty of scenarios where you might suffer from heatstroke.

Feel the Heat

When you overheat, your body is failing to regulate its core temperature because of a dramatic loss of salt and water through excessive sweating. Every cell in your body needs water to perform, and the sodium and chlorine in salt keep your muscles functioning properly. If you overheat, you'll get heat cramps, followed by heat exhaustion and, finally,

heatstroke.

The Stroke

When you fall victim to heatstroke, your body has completely failed to regulate its temperature, and you can no longer sweat to cool down. You'll know you're in the midst of

heatstroke if you experience severe headaches, dizziness, nausea and vomiting, muscle twitches or spasms, confusion and aggression, red or hot skin, an increased heart rate, hallucinations or unconsciousness.

Cool It, Buster

If you experience symptoms of heatstroke, head for some shade and lie down. Elevate your feet, loosen your clothing and drink water. If you're with someone else, pour cool water on your skin and have them fan you vigorously. If you're alone, fan yourself without expending too much energy. Even in a survival scenario when water is scarce, don't conserve your H2O -- heatstroke can kill you. Douse a towel, shirt or bandana in some cool water and apply it to your armpits and groin area to help lower your overall body temperature.

Recovery

Once you start to cool down, you need to lie flat in the shade for a while. A good way to tell if your condition is improving is if your nausea subsides and your heart rate chills out to a steady, normal level. Once these things happen, you can think about moving again. When you do attempt to get up and walk around, take it nice and slow and continue to drink water. Stay in the shade as much as you can for the rest of your day. If you're at home, take the rest of the day off from yard work -- the grass can wait.