What does heat stroke means?

Heat stroke, also known as sun stroke, is a severe heat illness, defined as hyperthermia with a body temperature greater than 40.6 °C (105.1 °F) because of environmental heat exposure with lack of thermoregulation. This is distinct from a fever, where there is a physiological increase in the temperature set point of the body. Before a heat stroke occurs people show signs of heat exhaustion such as dizziness, mental confusion, headaches, and weakness.

Heat stroke occurs when thermoregulation is overwhelmed by a combination of excessive metabolic production of heat (exertion), excessive environmental heat, and insufficient or impaired heat loss, resulting in an abnormally high body temperature. Substances that inhibit cooling and cause dehydration such as alcohol, stimulants, medications, and age-related physiological changes predispose to so-called "classic" or non-exertional heat stroke (NEHS), most often in elderly and infirm individuals in summer situations with insufficient ventilation. Exertional heat stroke (EHS) can happen in young people without health problems or medications, most often in athletes or outdoor laborers or military personnel engaged in strenuous hot-weather activity, or in certified first responders wearing heavy personal protective equipment. In India, hundreds die every year from summer heat waves.

Preventive measures include drinking plenty of cool liquids and avoiding excessive heat and humidity, especially in unventilated spaces such as parked cars that can overheat quickly. Treatment requires rapid physical cooling of the body.