I tried not to panic. I was floating effortlessly in a pitch-black tank filled with salty, skin-temperature water, wearing earplugs and nothing else. Within minutes I could no longer feel the sponge in my ears or smell the musty scent of water. There was no light, no smell, no touch and – save for the gasping of my breath and drumming of my heart – no sound.

I was trying out North America’s avant garde drug: sensory deprivation. Across the continent “float houses” are increasing in popularity, offering eager psychonauts a chance to explore this unique state of mind. Those running the business are quick to list the health benefits of frequent “floats”, which range from the believable – relaxation, heightened senses, pain management – to the seemingly nonsensical (“deautomatization”, whatever that means). Are these proclaimed benefits backed up by science or are they simply new-age hogwash?