What is Cryonics, how does Cryosleep work and what happens when a person is cryogenically frozen?

Cryonics promises people the chance of being brought back to life many years in the future.

The hope is that people with terminal illnesses might be woken up a time when such diseases and illnesses are curable. How does it work and is it real?

What is Cryonics?

Cryonics is the process of cooling bodies that cannot be kept alive medically to sub-zero temperatures in the hope they can be brought back to life in the future.

It is based on a theory that the brain can retain memory and personality while frozen and that one day scientists will able to successfully defrost and heal the bodies.

Four facilities in the world cryopreserve bodies at about -196C, three in the US and one in Russia.

There is currently no way to resuscitate bodies that have been cryogenically frozen although some believe the technology will be developed in the future.

How does it work?

1 Once a person wishing to be cryogenically frozen has died, a preservation company is informed

2 The response team will then attempt to keep the person’s blood pumping in their body, injecting the body with chemicals and packing them in ice

3 At the cryonics facility, the body’s blood is removed with it replaced with organ preservation solution

4 The body’s blood vessels are then injected with a solution in an attempt to stop ice crystals forming in the body

5 The body is then cooled to -130C

6 The body is finally placed into a container of liquid nitrogen and kept at -196C

Can humans be successfully frozen and defrosted?

At the moment, no. The current problem we face with cryogenically freezing human bodies is that when our cells freeze, they fill with ice crystals.

These ice crystals break down as our bodies are warmed up again and ultimately leave us as a lot of mush.

Humans of course have made advances in this field - we can successfully freeze and defrost sperm, embryos and eggs.

It is hoped that these barriers will be overcome and those frozen will eventually be woken up.

The first person to be cryopreserved was Dr James Bedford in 1967.

In 2014 about 250 people had been cryopreserved with 1,500 more having made arrangements for the procedure.

What is Cryosleep?

Cryosleep is most famous as a science fiction trope, whereby an astronaut would be placed into a state of suspended animation, either with a drug or, indeed, cryonics.

In Interstellar and 2001: A Space Odyssey for example, cryosleep preserves the human bodies so despite travelling for years they barely age a day.

Medically, however, cryosleep is not a real term.

That said, historically, the cold has been used a healing tool for thousands of years. Medically induced hypothermia has been utilised since Hippocrates.

The trick was to cover a devastating (or minor) wound in snow or ice to slow the flow of blood and grant the body enough time to heal.