Prolonged exposure to a cold environment, such as water or weather, is the most common cause of low body temperature, known as hypothermia, Mayo Clinic states. Medications and health conditions, such as anorexia nervosa, hypothyroidism and stroke, may also interfere with the bodyﾒs temperature regulation, increasing the risk of hypothermia.
Hypothermia develops when heat loss occurs faster than heat production, causing body temperature to fall from normal temperature of around 98.6 degrees Fahrenheit to below 95 degrees Fahrenheit, according to Mayo Clinic. Cases of harmful cold exposure are often exacerbated by risk factors such as wearing clothing that isnﾒt warm enough for the harsh environment or being stuck in a cold or wet area after a fall. Young children and the elderly are most vulnerable to hypothermia because their bodies are less efficient at preventing heat loss.
In cold water, heat loss occurs as much as 25 times faster than in cold air temperature, WebMD notes. The body attempts to preserve heat in cold environments by narrowing the blood vessels and triggering repetitive muscle activity, commonly known as shivering. If the body can't conserve heat, vital organs gradually go into protective mode and try to reduce further heat loss by shutting down. The onset of hypothermia slows down heart rate, brain activity and breathing rate, causing fatigue, drowsiness, memory loss, impaired coordination and slowed speech.