"Mad dogs and Englishmen go out in the mid-day sun."
-- lyrics by Noel Coward
Desert dwellers know there's a very good reason for mid-day siestas, avoiding blasting sunlight and hot temperatures.
National Park visitors don't always understand the need to avoid the heat of the day, which is why dehydration, heat exhaustion, heat stroke and hyponatremia (low sodium blood level) can put a damper on activities, or even send visitors to the hospital.
The key to desert travel and survival is water and salty snacks, said Tod Schimelpfenig, of the Wilderness Medicine Institute, noting that the rule of thumb is a gallon of water per day. Perspiration is how your body regulates temperature, so if you don't have enough water, your body will overheat. Minor dehydration triggers thirst, but as dehydration becomes more serious, said Schimelpfenig, the body starts to lose its ability to regulate temperature. Symptoms of heat stroke include disorientation, combativeness and hot skin, he added. The remedy is to find some cool shade, rest and re-hydrate, said Schimelpfenig.
Yet too much water can be a problem too, said Schimelpfenig, because the sweat flushes sodium out of the body -- that's why salty snacks are needed, to keep the sodium balance up in the blood.
"Marathon runners encounter hyponatremia, but so do high school football players in those August drills. They're drinking too much water," he said, losing the needed sodium in their blood.
"You want to smart about your intake of water or salt," Schimelpfenig said.