Planning a trip to Death Valley? You might be worried about heat stroke.
Don't be. The real threat posed by this famous U.S. desert valley -- and other deserts -- is dehydration, says an article on the University of California at Santa Barbara's Web site.
Dehydration -- losing water too rapidly through perspiration -- is the opposite of heat stroke, which is caused when high humidity prevents the body from sweating enough to cool off.
So drink plenty of water if you're in the desert. You can lose two gallons of water just sitting in the shade on a hot summer day. Losing four gallons is usually fatal.
