I tried floatation therapy, a crazy womb-like sensory deprivation technique that can be hallucinatory

Your can't feel your body, or the water enveloping you. Can't see the roof above you. You don't even wear swimwear in the tank, to ensure there are no distractions, whatsoever. You're in an eight-foot pod, but you might as well be drifting in the night of space.

In that void, your hearing takes on outsize importance. The pod is insulated and noise in the building is kept to a minimum (and you wear earplugs for good measure), meaning almost nothing leaks in.

So you're trapped with the noises of your body. Your breathing and heartbeat beats a constant rhythm. You hear every blink — even the movements of your eyes in your sockets.

I felt adrift, like I was moving, spinning slowly, though I stayed quite still, not even touching the edges. And in that disorientating emptiness, the mind wanders.

For starters, it is intensely relaxing. Returning to the real world afterwards was a shock — but more on that in a second.

With nothing to entertain it, your mind can play tricks on you. For some people, it can even induce hallucinations. 

I found myself hovering in that twilight state between awakeness and sleep. My mind ran in a game of free association — castles, clouds, music, shapes! It definitely wasn't a hallucination — not how they're normally defined. But unconstrained by reality, my imagination was vivid and wild. 

At one point, it felt like I was hearing Hillary Clinton's voice right of the edge of my hearing, not quite distinct. (I had watched one of the presidential debates live the night before.) I wasn't really hearing it, and on an intellectual level, that was obvious. If I focused, it would instantly dissipate, and I'd be lying alone in the darkness. But the moment my mind began to wander... there it was again!

For some people, floatation therapy is useful as a relaxation tool, or a kind of aid to physiotherapy. But others view it as a technique for enhancing meditation — and some can even consider it a spiritual experience.

"Some people can have flashbacks to certain points in their life, they can see certain geometric patterns," said Floatworks director Chris Plowman. "You sort of go in between an awake state and a dream state, and that's when you can have these almost psychedelic experiences."

Would I go again? I'd definitely consider it, though at £50 ($62) for a one-off session, it's not cheap. Plowman recommends you float regularly to get the most of it, with repeat sessions often offering enhanced effects.