On Human Hibernation
Imagine that your childhood dream of being an astronaut is finally in arm’s reach: NASA is looking for well-educated 40-somethings with solid bone structures, medical training, an unusual ignorance of cancer awareness and nothing to lose. You are about to put the win in Darwin! Just one problem… the mission NASA is planning will be going to Mars and the funds are drastically reduced, thus, you can go, but you can’t use up any precious space for luxuries like food, water or toilets. Space plumbing is complicated and costly, storing food and water is expensive too. For a flight to Mars, the bare minimum of food, e.g. granola bars, would amount to 400kg that have to be carried and stored. That’s a few millions right there. And a space toilet might amount to a staggering 19$ Mio. Now as the gravity-spoiled human that you are, you are wondering if the Mohawk-wearers at NASA have lost their mind by wanting to eliminate said amenities but perhaps they are on to something –
What NASA is envisioning is hibernation. Instead of wasting energy and producing waste, they would rather see the astronauts having a good nap just like the brown bear.
Many animals hibernate in winter. The arctic ground squirrel will drop its body temperature to barely 0°C and you may try but rousing it will be a feat. Bats also drop their body temperature but unlike squirrels, they can be easily disturbed, classifying them as facultative hibernators. Then there is also the Common Poorwill (with a poor will to stay awake?), he is named “The Sleeping One” in the Hopi language and the only known bird to deserve the name.
But relevant to NASA and science in general, is the brown bear. Unlike its hibernating buddies, he does not drop his body temperature by much. Bears have been found to hoover somewhere between 37°C and 30°C. Why that is so interesting, is because it is awfully hard for a large animal to heat up after an extended period of being cold, therefore the fact that large animals like bears can hibernate without the risk of dropping their body temperatures too low, is a circumstance applicable to humans.
Usually, humans don’t hibernate. But there have been a few cases of accidental hibernation of humans that are rather surprising.
In 2006, a 35-year old Japanese man named Mitsutaka Uchikoshi managed to walk over a mountain, slip in a stream and break his pelvis, landing him in a field unable to move. Naturally, when you break your pelvis on a lonely mountain side you are doomed. So Mister Uchikoshi remembers seeing the sun on the next day and feeling… very comfortable. That’s the last thing he remembers until he was found 24 days later by a mountain climber and send to a hospital. The doctors in said hospital presumed him dead, seeing that he lost a lot of blood, hadn’t drunken or eaten in 24 days and had a body temperature of 22°C. In true Japanese superhero fashion however, Mitsutaka woke up, most likely scaring the medical staff to death. He walked out of the hospital shortly thereafter with no brain damage whatsoever. He is not the only example. In February 2012, a Swedish man was found in a sleeping bag in his snowed-in car near Umea, telling the freaked out passer-by’s he has been there since the 19. December, only occasionally eating some snow. My favourite is probably the tale of Anna Bågenholm, a Swedish lady who broke into a frozen lake in Norway, head-first, in 1999, submerging into the ice and getting trapped under a 20cm thick ice blanket. Her two friends on arrival only saw her skies sticking out and held unto them until rescue teams arrived. Anna had found an air pocket to breathe and somehow stayed conscious for 40 minutes. The total rescue, with various failed attempts, took an hour and twenty minutes however.
It took the ambulance helicopter another hour to transport her to the Tromsø University Hospital (note to self: don’t go skiing in areas too far away for any reliable survivability). Even though her friends, both doctors, performed CPR on her and she received oxygen, she did not breathe. Her body temperature was recorded at 13.7°C, the lowest temperature ever recorded in a human being from accidental hypothermia. The anaesthesiologist, who treated her in the hospital, commented that she looked “absolutely dead”. Anna eventually started to breathe again and not just that, she recovered enough to have, as of 2009, worked as a radiologist in the hospital that saved her life.
These and other examples seem to indicate that under special circumstances, humans seem to have a shot at hibernation. Could we somehow artificially make someone hibernate? If we could, Mars could be a much more realistic journey option and if we could extract blood from hibernating humans, we could inject it into donor organs and preserve them for over double the time we have now (6 hours) and thus, make survival for transplant patients more likely.
But it is important to point out that most people whose core body temperature plummets to less than 28°C do indeed die. While Anna’s baseline rate (the energy a person uses at rest) dropped to 10% of what is normal, requiring her to need very little oxygen, most people will have lasting brain damage from a lack of O2.
But some can be resurrected. If we learn how to hibernate humans simply and safely, it might be one small step for a fridge but one big chapter for the history books.