Hypothermia is caused by losing more heat than the body can generate. The most common cause of hypothermia is exposure to a cold environment. A cold environment doesn’t necessarily mean the outdoors; those under anesthesia may be more prone to hypothermia because of altered thermoregulatory mechanisms.
Other causes or risk factors include trauma or surgical wounds, fatigue, and alcohol intoxication. For babies, sleeping in cold bedrooms can be a risk factor.