The Curious Case of Human Hibernation

The survival stories of mountain climbers may be a clue to suspended animation. (Photo by Tim)

Hibernation is a state characterized by inactivity, slower metabolism and lower body temperature. Hibernating animals most often do so to survive food scarcity, especially during the winter. Man is not considered a hibernating animal, but a glance at modern science and strange accounts from the past suggest we may have to revise our views in the future.

James Braid, the father of hypnotherapy and a man with a fascination for the occult, recorded several odd cases of humans surviving hibernation-like conditions in his 1850 book Observations on Trance (link). In his most famous account an Indian fakir was buried alive in the presence of Sir Claude Wade, the English governor at the time. After remaining in the ground for several months, the fakir was reportedly exhumed and restored to consciousness in good health.

No one knows if Braid and Wade were telling the truth, but findings of the same nature have been reported even quite recently. A 1998 paper from Physiology describes two Indian yogis performing similar stunts, although the durations were much shorter (link):

One yogi went into a state of deep bodily rest and lowered metabolism and was able to remain in an airtight box with no ill effects and no sign of tachycardia or hyperpnea for 10 h.

In a different study done in a more naturalistic setting on a different adept, Yogi Satyamurti (70 yr of age) remained confined in a small underground pit, sealed from the top, for 8 days. He was physically restricted by recording wires, during which time electrocardiogram results showed his heart rate to be below the measurable sensitivity of the recording instruments.

A hundred and ten years ago the British Medical Journal ran a short article titled Human Hibernation (link). The article, reprinted in 2000, is a peculiar account of how poor Russian peasants allegedly survive famine by sleeping for half of the year. I'm quoting the full article here:

A Practice closely akin to hibernation is said to be general among Russian peasants in the Pskov Government, where food is scanty to a degree almost equivalent to chronic famine. Not having provisions enough to carry them through the whole year, they adopt the economical expedient of spending one half of it in sleep. This custom has existed among them from time immemorial.

At the first fall of snow the whole family gathers round the stove, lies down, ceases to wrestle with the problems of human existence, and quietly goes to sleep. Once a day every one wakes up to eat a piece of hard bread, of which an amount sufficient to last six months has providently been baked in the previous autumn. When the bread has been washed down with a draught of water, everyone goes to sleep again. The members of the family take it in turn to watch and keep the fire alight.

After six months of this reposeful existence the family wakes up, shakes itself, goes out to see if the grass is growing, and by-and-by sets to work at summer tasks. The country remains comparatively lively till the following winter, when again all signs of life disappear and all is silent, except we presume for the snores of the sleepers.

This winter sleep is called 'lotska'. These simple folk evidently come within '0 fortunatos nimium sua si bona norint!'

In addition to the economic advantages of hibernation, the mere thought of a sleep which knits up the ravelled sleeve of care for half a year on end is calculated to fill our harassed souls with envy. We, doomed to dwell here where men sit and hear each other groan, can scarce imagine what it must be for six whole months out of the twelve to be in the state of Nirvana longed for by Eastern sages, free from the stress of life, from the need to labour, from the multitudinous burdens, anxieties, and vexations of existence.

Don't you just love the poetic style of scientific writing back in those days? The lotska sounds more like an urban legend than an accurate description of lowered metabolism, but in 1906 – six years after the original article appeared – The New York Times ran a story on starving peasants in Russia "lying motionless for days at a time, in order to weaken the pangs of hunger". A few days later, there was a letter to the editor with the following comment on the story (link):

This exigency may be akin to the pseudo-hibernation habitually practiced by Russian peasants in the northern provinces, notably in the Pskov district. If such is the case, the hardships endured by the peasants this Winter may not be as great as the casual reader might be led to believe.

True, the pseudo-hibernation which is general in Pskov has resulted from the fact that famine is well-nigh chronic there; but by pratice from time immemorial the peasants have become accustomed to imitate the habit of the bear and the marmto in Winter, until now the custom is regarded by them as one of the normal conditions of human existence. They have a name for this Winter sleep. It is called "lotska".

In the brief Autumn the housewives prepare a sufficient quantity of hard, black bread to last until Spring. When Winter sets in in earnest the family lie down around the stove and go to sleep. Once in the twenty-four hours everyone wakes up, to nibble at a piece of the black bread, which is washed down with a drink of water. Then all go to sleep again. The members of the family take watch and watch about to keep the fire going.

This pseudo-hibernation lasts until Spring, or upward of six months, when the peasants take up their humble tasks again and are busy until the succeeding Witner, when silence reigns over the frozen land once more.

The writing is somewhat similar to the original 1900 article, but it's not clear whether the writer is the same. Searching for more information on this ancient art of lotska doesn't yield much new, so we're left wondering if the peasants really spent their long winters this way.

The accounts above are of people willingly undergoing depressed metabolism and what might be called a hibernation-like state, but what about people who fall into similar states by accident?

Fast forward about a hundred years, to 1999, when Swedish radiologist Anna Bågenholm got into a skiing accident which left her trapped under a layer of ice (link). For 1 hour 20 minutes, she was in freezing water, suffering the most extreme hypothermia ever recorded in a human. When she was rescued and taken to a hospital, her body temperature was a lethally low 13.7 °C.

After 40 minutes in the icy water, Bågenholm was in cardiac arrest. During cardiac arrest, the normal circulation of blood stops due to failure of the heart to contract effectively. As a result, oxygen is no longer delivered to the body and the brain, which leads to loss of consciousness. Brain injury usually happens after five minutes.

Strangely, despite minor symptoms related to nerve injury, no permanent brain damage was diagnosed in Bågenholm's case. One of the doctors treating her reported that "her body had time to cool down completely before the heart stopped. Her brain was so cold when the heart stopped that the brain cells needed very little oxygen, so the brain could survive for quite a prolonged time."

In 2006, a Japanese man named Mitsutaka Uchikoshi went missing during a mountain climb with friends (link). After leaving his friends to descend the mountain on his own, he tripped and lost consciousness. When he was found 24 days later, his pulse was almost non-existent, his organs had shut down and his body temperature was 22 °C.

Upon hearing his remarkable story, some doctors deemed it physiologically impossible that he had survived for so long without any water. His metabolism had apparently grinded to an almost complete halt. One of the doctors treating him commented: "He fell into a hypothermic state at a very early stage, which is similar to hibernation. Therefore, his brain functions were protected without being damaged and have now recovered 100%. This is what I believe happened".

In late December 2008, Magdeline Makola was abducted and tied up in a car boot (link). After 10 days of drifting in and out of consciousness in below-freezing temperatures, she was found by two traffic police officers. According to doctors, 48 more hours and she would've been dead; in a warmer temperature and she might not have made it through the 10 days. The hypothermia may have saved her life.

In a fascinating TED Talk from 2009, Ken Kamler describes the worst disaster in the history of Mount Everest, and the story of one climber's miraculous survival (link). Due to the fierce wind and extreme conditions, he was not able to return to the base camp from higher up in the mountain and instead just lay there in the snow, too weak to move.

Amidst the chaos, everyone presumed he was dead, until he burst into Kamler's medical tent seemingly out of nowhere, having forced himself to get up and trek back to base camp after 36 hours of being buried in the freezing snow.

Kamler tells the story as an example of the power of the human mind. The climber told him that while laying there in under the snow, he'd thought of his wife and child at home and decided that he couldn't just die there on the mountain. He had to survive for their sake. And so, severely frostbitten and suffering from hypothermia, he somehow managed to not only come back to life but to walk without help to base camp.

The human mind is undoubtedly capable of great things, but reading all these stories, I'm left wondering whether there is something else at play. A recurring theme in many of the cases seems to be that these people's metabolism was slowed down due to freezing temperatures and low oxygen. At mountain altitudes, for example, temperatures and oxygen are lower than at ground level. Even the yogis' tricks were done in small airtight spaces.

For the past years, cell biologist Mark Roth has examined the relationship between oxygen, metabolism and suspended animation. In 2005, he showed that mice exposed to small amounts of hydrogen sulfide put them in a state of hibernation, from which they could be brought back unharmed. The hydrogen sulfide caused the mice's core temperature to drop from 37 °C to 11 °C and their metabolism to slow by 90 percent. Hydrogen sulfide, which is naturally present in the body but toxic at large doses, works by preventing oxygen from binding.

Using freezing temperatures to induce hibernation is generally a bad idea in many species. Warm-blooded animals like humans react to cold by cranking up the internal heating system and burning more oxygen, which spells trouble. According to Roth, the key to lowering metabolism safely is to combine cooling with something that reduces the demand for oxygen (link):

I’m going to be talking [at TED] about unpublished work where we have demonstrated that if you make certain animals cold in an animated state, you kill them. But if you make those same animals cold, but they are now suspended, they all survive.

During the same TED Talk, he mentions experiments showing that if you reduce the oxygen content in the air slightly, roundworms die, and if you reduce it a lot – down to 10 ppm – they stop moving and appear dead but are in fact alive in a state of suspended animation. Unlike their animated and lively friends, these suspended roundworms can be put into cold temperatures without harm.

Exposing an organism to hydrogen sulfide is another way to achieve the same effect as reducing the oxygen content of a container or a room. By binding at the same cell site as oxygen, hydrogen sulfide reduces the need for oxygen, depressing metabolism. Roth theorizes that perhaps hydrogen sulfide production was increased in Bågenholm's own body when she fell under the ice, thus preventing her from dying from the cold.

The first practical application of this technique is surgery, which requires mild hypothermia to prevent harming patients. Even with a small amount of injectable hydrogen sulfide, which Roth's company has developed, the results are apparently better than with a traditional approach. Safety studies are already done, and human trials are underway.

While this is undoubtedly a great medical breakthrough, I can't help but think of other possible applications. What Roth has done is deanimate a mouse by reducing its metabolism and then bring it back to life unharmed. If the human trials are succesful, could this mean hydrogen sulfide might be used even outside surgery? Are we talking about a potential lightweight version of cryonics?

At this point, no one knows. Although similar findings have been confirmed by another lab using mice, two other labs reported that hydrogen sulfide did not induce hibernation in sheep or pigs (link, link), casting doubt on the feasibility of induced hibernation in large mammals.

Also, Roth didn't do lifespan experiments with his mice, so we don't know whether suspending them for longer periods of time might have made them live longer. But given that the connection between lower metabolism and extended lifespan has been shown in several other experiments, I certainly wouldn't be surprised if it did.

Makes you wonder if we could one day be like those poor Russian peasants, sleeping through the hard times and waiting for a brighter future.

For more information on technology and life extension, see these posts:

Biotechnology and the Future of Aging
How to Live Forever: My 5 Steps to Immortality
Aubrey de Grey in Helsinki, Finland
Anti-Aging in the Media: Rolling Stone on Ray Kurzweil