Imagine you are in a small underground chamber, no bigger than a prison cell. The door is locked and the lights are switched out. It is not just dark; it's pitch black. And the silence is all-encompassing. Could any human, in fact, endure such total sensory deprivation without losing their sanity? That was what British scientists sought to discover in an extreme experiment that placed six volunteers into a total isolation chamber for 48 hours.

So, who would be brave, or foolish, enough to undergo a similar ordeal voluntarily? Step forward Adam Bloom, 37 who was confident he could cope well with the deprivation. But Bloom described what happened when the door was slammed shut:

I spent the first half an hour in the bunker talking, singing, and making jokes, but that quickly got boring … In the absence of a watch or sunlight, I'd totally lost track of time. I dozed on and off … but I had no idea whether it was day or night … At one point, I started singing and then I burst into tears. I can't remember the last time I cried.

After 40 hours he began to hallucinate. "I felt as though the room was taking off from underneath me. For the first time, I realized that the lack of stimulation was driving me close to insanity." But then for Bloom, there was an unexpected outcome—gratitude. Bloom explains:

When we'd arrived at the bunker before the experiment, I had thought it was all rather bleak. The exterior was all overgrown and the bunker was an eyesore. But when I left after 48 hours, I noticed how green the grass was, how blue the sky was, and hundreds of yellow buttercups. It was staggeringly beautiful. Even washing my hands under the [faucet] was amazing. I made a vow that I would never [again ignore] and not appreciate my surroundings.