THE  HISTORY  OF  FLOATATION

John C. Lilly, a medical practitioner and neuro-psychiatrist, developed the flotation tank in the 1950s. During his training in psychoanalysis at the National Institute of Mental Health (NIMH) in Bethesda, Maryland. Lilly commenced experiments with physical isolation. In neurophysiology, there had been an open question as to what keeps the brain going and the origin of its energy sources. One answer was that the energy sources are biological and internal and do not depend upon the outside environment. It was argued that if all stimuli are cut off to the brain then the brain would go to sleep. Lilly together with his associate Dr. Jay Shirley, decided to test this hypothesis and, with this in mind, created an environment which totally isolated an individual from external stimulation. From here, he studied the origin of consciousness and its relation to the brain. Then the very first floatation tank evolved.

Lilly’s first tank was one in which the floater was suspended upright, entirely underwater, head completely covered by a  complicated head-masks in order to breathe underwater; however, the mask detracted from the isolation experience.  The tight fit of the mask seal around the face and the retention strips wrapping around the back of the head were uncomfortable in long sessions.  The constant hissing of the air valves and bubbling exhaust air out of the mask, prevented the possibility of silence.  The faceplate of the mask was typically solid black for visual isolation, but then the tank user needed halp entering and leaving the isolation tank since the mask blinded them.

Over the years, Lilly continued his experiments with floatation, simplifying and improving the general design of the tank.  Dr. Lilly found that he could float in a more relaxing supine position, rather than suspended feet downward in fresh water, if more buoyant salt water was used.  By the early 1970’s, Lilly had perfected the floatation tank in much the design used today.

In newer tanks, Epsom salt is added to the water in the tank to raise the density of the water above the density of the human body so that the subject floats with his or her face above the water.  However, since the ears are submerged when the subject is in the relaxed position, hearing is greatly reduced, particularly when ear-plugs are also used.  When the arms float to the side, skin sensation is greatly reduced because the air and water are the same temperature as the skin, and the feeling of a body boundary fades.  The sense of smell is also greatly reduced, especially if the water has not been treated with chlorine.

Other refinements, such as water heaters with thermostats sensitive enough to keep the water at perfect temperature, an air pump to keep the air in the tank fresh, and a water filter for the re-use of the Epson salts, were added over the years. 

Peter Suedfeld and Roderick Borrie of the University of British Columbia began experimenting on the therapeutic benefits of flotation tank usage in the late 1970s. They named their technique "Restricted Environmental Stimulation Therapy" (REST).

Excerpt from Wikipedia