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What happens if you are left alone in the dark in solitary confinement for days on end? The result is called sensory deprivation and the human mind struggles to cope with it.

Adam Bloom is a stand-up comic, an extreme extrovert who admits he thrives on stimulation.

He is one of six volunteers who have agreed to be shut inside a cell in a nuclear bunker, alone and in the dark. And for Bloom it will be particularly hard.

Within half an hour of being locked up at the start of the experiment, all of the subjects lie down and go to sleep. But the real ordeal will begin when they wake up and find they have no idea what time it is.

Throughout the 48 hours they are being monitored by a psychologist and filmed for a BBC Horizon documentary.

As the hours pass, seeing and hearing nothing, they become increasingly disoriented.

After 24 hours Bloom is suffering. The subjects have been encouraged to describe how they are feeling but know that while their words may be heard, no one will respond.