Finally, putting a bit of salt in the drinking water doesn't help, and may actually hurt. I've spoken to some of the Grand Canyon rangers on this topic as well and have learned a good deal from them. It happens when people drink a lot of water but don't eat much due to the heat and their own exertion. Cramps, nausea or fainting can follow.
Severe cases can be fatal.
To prevent this condition, it's advised you force yourself to eat on a regular basis and drink sports drinks rather than plain water. I would argue vehemently that sports drinks DO help, although with anything there are limits. Certainly, there is plenty of evidence that people can function in high temperatures. They key is to acclimate to the heat and take precautions. Express yourself in our Gear Forum .