Author: Dr. Andreas Moustris MD, MSc
Despite large variations in environmental temperature, the core temperature of the human body remains remarkably stable. This is achieved through a number of physiological homeostatic mechanisms that are regulated by the hypothalamus. The latter is a neural structure located at the base of the brain that essentially functions like a thermostatic switch: when the temperature of the body rises, it coordinates the dilatation of peripheral veins, a boost in cardiac output and increased production of sweat by the relative glands, so that the excess of thermal energy is dissipated to the environment.
However, under certain circumstances, these homeostatic mechanisms may not be sufficient. In that case, the core temperature of the body gradually increases, leading to the emergence of a spectrum of symptoms. The first stages constitute the syndrome of heat exhaustion, that may lead to:
- Cramps (painful muscle contractions)
- Fatigue and malaise
- Nausea and vomiting
- Excessive sweating
- Rapid breathing and tachycardia
- Intense thirst
- Temperature > 37°C
If heat exhaustion is left untreated, it may lead to heat stroke, a serious medical emergency, that is characterised by:
- Temperature > 40°C
- Collapse of the thermoregulating mechanisms of the body
- Symptoms indicative of diffuse brain dysfunction (confusion, hallucinations, tremor, incoordination, difficulty speaking, somnolence and seizures)
- Multiple organ failure
Who gets heat exhaustion and heat stroke?
Young, otherwise healthy individuals, may get heat stroke by engaging in strenuous exercise during a very hot and humid day. When heart stroke is non-exertional, most cases tend to involve elderly people with chronic diseases that affect thermoregulatory mechanisms or impede their removal from a hot environment.
Particularly susceptible groups are:
- People with cardiorespiratory diseases
- Infants and young children
- People with chronic neurological diseases
- People taking specific categories of drugs:
- Diuretics and beta-blockers
- Neuroleptics (antipsychotics)
Avoiding heat exhaustion and heat stroke
- Drink plenty of fluids regularly: dehydration plays a significant role in the development of heat-related illnesses. Don’t wait until you feel thirsty in order to drink water or beverages.
- Avoid alcohol, because it increases the chances of getting dehydrated.
- Avoid exercising under extreme temperatures. Prefer to work out early in the morning or during the evening. If you feel unusual fatigue, nausea, dizziness or headache, stop exercising immediately, move to a cool place and drink plenty of water.
- Wear light and loose-fitting clothes, so that the evaporation of sweat is not impeded.
- Take cold showers.
- Eat light meals, plenty of fruits and salads.
- If you suffer from Multiple Sclerosis, extreme temperatures may lead to a temporary neurological deterioration (Uhthoff’s phenomenon). It is advisable to stay and work at places with air-conditioning during heatwaves.