A sensory deprivation tank, also called an isolation tank or flotation tank, is used for restricted environmental stimulation therapy (REST). The first tank was designed in 1954 by John C. Lilly, an American physician and neuroscientist. He designed the tank to study the origins of consciousness by cutting off all external stimuli. In the 1970s, commercial float tanks were created and began being studied for possible health benefits.
The water in a sensory deprivation tank is heated to skin temperature and nearly saturated with Epsom salt magnesium sulfate), providing buoyancy so you float effortlessly,allowing for near zero gravity. In addition there is the option to have no light or sound. As you float weightlessly in the silence and darkness, the brain enters into a deeply relaxed state. Studies suggest time spent floating in a sensory deprivation tank may have some benefits in healthy people, such as muscle relaxation, better sleep, decrease in pain, and decreased stress and anxiety.