Hypothermia: What happens when your body freezes?

Our bodies require a core temperature of 36.5 to 37 degrees Celsius (97.7 to 98.6 degrees Fahrenheit).

Although it does everything in its power to maintain that temperature, the body can only do so much on its own — more than five million people die every year due to freezing or excessively hot temperatures.

Metabolism regulates body temperature

The body regulates its core temperature through metabolism-activating receptors. 

To maintain the ideal level of warmth, the metabolism ensures that the food we consume is broken down so that our cells can utilize nutrients. When it's cold, the body needs more energy, and our blood vessels constrict to avoid losing too much heat.

From cold fingers to hypothermia

But if those vessels constrict too much, cells lack the necessary blood for circulation. They become brittle, causing the body to hurt. This pain will first hit the fingers, toes, nose and ears. If the body temperature continues to drop, vital organs like the heart, lungs and brain will cease functioning.

Hypothermia occurs when the body temperature deviates by two or more degrees from the norm. In order to protect itself, the body goes into overdrive to try and compensate for the low temperature, causing trembling.

People in early stages of hypothermia can also experience slow or slurred speech, according to Michael Kuiper, a neurologist from the Medical Center of Leeuwarden in the Netherlands. Kuiper regularly treats hypothermia patients in his clinics. 

Lack of trembling a bad sign

At a body temperature of 32 degrees Celsius, the trembling stops. This isn't a good sign because it means our brain and nerve endings have lost the ability to transmit signals, causing numbness in the arms and legs.

In this phase, the pain subsides, but the body can barely move. We lose the ability to speak or think clearly. By now the body's emergency signals are activated, but at some point they will stop working too.

Kuiper said this stage is marked by paleness, mental confusion, memory loss and, eventually, coma. People experiencing hypothermia of this intensity may express a sense of peacefulness, Kuiper said, which can confuse friends and family trying to help them. 

"A lot of people have given us a sort of experience when they were hypothermic and were eventually saved," said Kuiper. "They said they didn't want to go anymore, that they just wanted to sit on a bench in the snow. They were at peace…they just didn't care about it anymore. When it starts, it is difficult, you feel unwell — you basically feel terrible. But when it gets worse, that pain goes away."

If you are with a friend or family member who may be experiencing hypothermia, Kuiper said a telltale sign the situation has become dangerous is when that person says something like "just leave me here" or "I don’t want to go on."

How long it takes a person to reach the critical stages of hypothermia will vary, he said, and depend on the rate of temperature loss. For some, it could take hours, but could take even longer for others. 

How to help

Kuiper said that although you may feel tempted to give a friend suffering hypothermia your own jacket or clothing, this could make the situation worse, because you are both experiencing the same low temperatures. Without proper clothing, you could start experiencing hypothermia yourself. 

"It is important that you obey the rules of first aid, and that is to look for danger and to look out for yourself … because if you don't do that, you can't help someone else," said Kuiper. 

He said you should only share clothes if you know you have enough or if the hypothermia is the result of exposure to water (falling into a lake or pond, for example) and not dangerously low temperatures on their own. 

If possible, bring the person to a warm place, like a car or nearby restaurant, and call the ambulance. Kuiper said it is important to make sure their head is covered, because that is where a lot of temperature is lost. 

Finally, Kuiper said that although a person experiencing hypothermia may appear dead at some point, it is not uncommon that even those with the worst symptoms can be revived once they reach heating. 

"The only good thing about hypothermia is that someone who may seem dead can be rewarmed and survive in a good neurological condition," he said.

Be careful with alcohol

Contrary to popular belief, attempts to warm oneself with mulled wine or a shot of vodka are futile.

Alcohol may initially cause the body to feel a sensation of cozy warmth from within — this is because it causes our blood vessels to dilate. When the body pumps the warm blood, however, it cools almost immediately. We may feel heat on the surface of the skin, but the body itself is still freezing, and our internal temperature continues to fall.

Freezing temperatures can cause paralyzation. The situation grows more dangerous as they drop.

Be proactive

Europe’s energy crisis is expected to cause precarity this winter, with many Ukrainian cities experiencing rolling electricity blackouts and gas prices skyrocketing across the bloc. 

Kuiper said that when faced with the cold, you should wear layers and cover your head. If you find yourself in a home that has lost heating, make sure everyone in the household is gathered in the same room, because warmth from bodies will help to naturally heat it. He also advised people to use plastic to cover up windows and crevices to avoid letting any cold air in by accident. 

He said he is concerned that over the course of the winter, people who fear high energy prices or lose traditional sources of heating will try to warm their homes with coal or old gas stoves, which can cause carbon monoxide poisoning. 

One way to avoid this is to use carbon monoxide detectors in the home.

Is freezing painless?

If the body temperature falls below 29.5 degrees Celsius, the cerebrum stops working. We become unconscious and hover between life and death.

Our heart slows, beating just once or twice per minute. At this point, blood can no longer be pumped through the body quickly enough to keep us alive, and death from the cold is almost certain. Science does not agree on whether this is a "gentle" death.

This article was originally written in German on December 16, 2018. It was updated on November 26, 2024, to reflect developments in Ukraine.