Heat Exhaustion

An effect of excessive exposure to heat occurring commonly among workers in furnace rooms, foundries, etc., although it may occur from exposure to the sun's heat (SUNSTROKE). It is marked by subnormal temperature, with dizziness, headache, nausea, and sometimes delirium and/or collapse. It is distinguished from HEAT STROKE, in which the body temperature may be dangerously elevated. (Dorland, 27th ed)