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Thursday, March 17, 2016

Rhinochill ~ could humans hibernate too ?

In the greatest epic Ramayana, there are some interesting characters. He was able to realise the mistakes and wrongdoings, tries to intervene and moderate, but bound by warrior ethics, fights and gets killed.  Kumbhakarna (lit. pot-eared) is a rakshasa and the younger brother of Ravana; despite his monstrous size and great appetite, he was described to be of good character.  It is stated that Kumbhakarna slept for six months, and when he awoke, he ate everything in the vicinity !

Torpor is a state of not being active and having very little energy.  Many would know hibernation better. While most mammals can adapt to the cold, many small mammals give up the struggle.  As winter approaches, large mammals can often migrate to warmer areas or grow a long, dense winter coat, but these options are not open to small ones. Small  mammals  need a high metabolic rate to maintain body temperature, they cannot increase this further when food is scarce.  Nature has a solution – they give up the struggle and allows body temperature to fall.  The deep sleep allows them to conserve energy, and survive the winter with little or no food.

Most hibernators prepare in some way for the winter. Some store food in their burrows or dens, to eat when they awake for short periods. Many eat extra food in the fall while it is plentiful. It is stored as body fat to be used later for energy. True hibernators go into such a deep sleep that they are difficult to wake and may appear dead. Their body temperature drops and breathing and heart beat slow down significantly.  

To differentiate, Torpor is a short-term reduction of body temperature on cool days. Hibernation is an extended form of torpor.  Could humans hibernate too ?

On cold, dark days it is tempting to imagine shutting yourself away until the warmer weather returns. Could humans ever hibernate in the same way animals do ? Vladyslav Vyazovskiy, associate professor of neuroscience at the University of Oxford has explained what torpor does to the body and how it could affect the human body in an article for The Conversation.

 Aside from providing a convenient way to avoid winter, one reason to find out might be the advent of long-distance space travel.  A journey to our nearest planet Mars would take around eight months using current technology. If we one day hope to visit another star system, even if we could travel at the speed of light, the journey would take years.  Being able to go into a state of long-term torpor would make such distances considerably less tedious for the astronauts and conserve vital resources.

It's still an open question but, at least in theory, we can't exclude that it might be possible.  Torpor appears to have evolved to effectively fill the gaps during those periods of the year when there is no need for certain animals to be out in the world, for example when food is scarce. Technically it refers to a regulated state of reduced metabolism, meaning the chemical reactions in an organism's body that keep it alive slow down. Heart rate, breathing and energy consumption all dramatically decrease and body temperature can also fall. When and for how long animals enter torpor can vary hugely, from many months of the year, to just a few hours a day over a period of a few months. Some animals, such as mice and hummingbirds, enter a state of torpor daily. Others, such as bears, go into prolonged periods of torpor during the winter, known as hibernation.

The fact that large mammals such as bears and even primates, such as the fat-tailed dwarf lemur of Madagascar can hibernate means that theoretically humans aren't too big or energy-hungry to enter torpor. Nor does our evolutionary origin prevent us from doing so, claims the expert. Last year, Dr Mark Schaffer from SpaceWorks Enterprises in Atlanta suggested a proposal for putting astronauts into hibernation. According to his plans, the astronauts would be put in stasis using a system called RhinoChill. This would reduce body temperature by about one degree per hour by supplying coolant through the nose. At a temperature of between 32°C (89°F and 93°F), which takes six hours to reach, the crew would enter stasis.

Stopping the flow of coolant would then wake the crew when they arrive at their destination. This means that on the journey to Mars, they could be placed in a fairly small capsule. Lowering body temperature and metabolism mean cells need less oxygen, enabling their survival in conditions when oxygen cannot be delivered. This process of artificial cooling in humans appears similar to spontaneous torpor in animals in that it includes reduced breathing, heart rate and metabolism. But the key difference is that animals seems to 'know' the way to safely and spontaneously enter torpor.

The way to get to Mars using the minimum energy involves launching in a specific window when the two planets are aligned in such a way that a craft can catch up to the red planet when launched from Earth and enter orbit. This launch window opens approximately every two years and two months, which is why mission to Mars often launch and arrive at similar times – such as India’s recent Mars orbiter and Nasa’s Maven mission.  The next window opens in April 2018, when Nasa’s next Mars mission – Insight – will launch towards the red planet, while the as-yet unnamed Mars 2020 rover will do the same when the next window opens in July 2020.

Interesting !!

With regards –S. Sampathkumar
17th Mar 2016-03-17

Science article credit :

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