Sweat acts like our natural air conditioner. As sweat evaporates from our skin, it cools us off. Our personal cooling system can fail, though, if we overexert ourselves on hot and humid days. This can result in heat exhaustion or a heat stroke, which is life threatening.
Heat exhaustion takes time to develop.
Fluids and salt are vital for health. They are lost as children and adults sweat a lot during exercise or other strenuous activities. It is very important to drink lots of non-alcoholic liquids before, during, and after exercise in hot weather. As strange as it seems, people suffering from heat exhaustion have low, normal, or only slightly elevated body temperatures. No sweating Deep breathing and fast pulse, then shallow breathing and weak pulse Dilated pupils Confusion, delirium, hallucinations Convulsions Loss of consciousness Heat stroke, unlike heat exhaustion, strikes suddenly, with little warning.