A future where humans are placed in hibernation to travel into space is a step closer after scientists proved they can put mammals into a sleep-state using ultrasound.

Many animals and birds are able to enter a torpor-like state in which they suppress their metabolism and reduce body temperature to conserve energy and heat during periods of extreme cold or lack of food.

Since the 1960s, scientists have proposed that inducing a similar state in humans could help protect patients with life-threatening conditions and allow astronauts to embark on long-distance interstellar flights with fewer supplies.

The concept of travelling through space in suspended animation has been at the heart of several science fiction films including Passengers, 2001: A Space Odyssey, and Interstellar.

Now, a team at Washington University in St. Louis has shown they can send rodents into a state of reversible hibernation by firing ultrasound pulses at their heads, stimulating the hypothalamus preoptic area in the brain, and causing their heart rates to halve and their temperature to drop.

They have called the phenomenon UIH - Ultrasound-induced hypothermia and hypometabolism.

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