The U.S. Centers for Disease Control and Prevention
reports that, on average, at least 1,000 people die each year from the condition that strikes when a person's core temperature dips below 95 degrees Fahrenheit. The stages of hypothermia begin when the body is losing heat faster than it can produce it. The condition typically affects people who abuse alcohol or drugs, elderly and very young people and the generally unhealthy, the National Institutes of Health says. Even babies who sleep in cold rooms can develop hypothermia, the CDC says.
Whether it's caused by exposure to cold weather or immersion in cold water, someone with hypothermia first begins to shiver to move muscles and generate heat, experts say. When the body stops shivering, that's a sign of significant trouble.
When hypothermia begins, the body's core functions work harder, pulling blood into extremities. Shivering is the body's involuntary survival instinct to jump-start muscles to maintain warmth.
If you start to shiver, shake it out.
"You should try to run, jump, move around. ... You should do anything you can to increase your body heat," said Jesse Schomberg, who works to educate Minnesotans about hypothermia at the Minnesota Sea Grant
It was zero degrees at 10 a.m. Wednesday in Minneapolis. Cold contributed to the deaths of 26 people in Minnesota between January and March 2014, the Minneapolis Star-Tribune reported.
can make a person dizzy, hungry, nauseous and make it harder to speak clearly. Motor skills will start to fail and a person may feel tired.
Children typically develop bright red, cold skin. Babies' crying will grow weak. On the rare occasion that someone survives hypothermia, they describe being in a state of extreme confusion.
If there are few survivors, and they were confused, how do we know so much?
and his assistants have artificially lowered his body temperature to the point of hypothermia at least 30 times, he said.
"Yep, I have that T-shirt," he said. "I've done this in very controlled settings, of course, and we've learned a lot."
The associate dean of kinesiology and recreation management at University of Manitoba in Canada studies the effects of extreme weather and physical exertion on the body.
Years ago he was a wilderness instructor in the mountains of Alberta, British Columbia, a job that inspired him to make a career of cold curiosities.
"When we took people into the woods, they always wanted to know about hypothermia and frostbite," Giesbrecht told CNN.
For a long time, medical experts believed that it would hurt a hypothermia victim to warm them right away, that might it might cause cardiac arrest or some other shock to the system, he said.
His work has concluded that a person should be warmed right away and as much heat as is tolerable should be applied to his or her upper core, he said.
Giesbrecht's experiments have also given hope to the survival odds for someone who falls into cold water and develops hypothermia.
He told Newsweek
in December that a person who is stuck under ice could survive 30 to minutes of drowning because in the event that the "the oxygen supply to the brain has stopped" because "a colder brain can survive a longer period of anoxia [an extreme form of low oxygen]."
A final, and bizarre thing hypothermia victims do
It's called "paradoxical undressing."
There are rare reports of people who have been in the last and most dangerous stage of hypothermia who feel the urge to rip off their clothes.
Little is known about these cases, Geisbrecht said, because there are so few people who've been resuscitated after this stage. Scientists don't know exactly why there's an urge to disrobe, he said. Paradoxical undressing has played a role in criminal cases because when a victim is found partially clothed, investigators sometimes assume wrongly that he or she was sexually assaulted, he said.