When my wife and I ran a floatation center, I had the opportunity to see the initial response of 100s of people to a floatation tank. I was surprised that many people responded with apprehension. Most of us have gotten used to getting into elevators, airplanes, MRIs and other enclosed places, but the floatation tank seems to trigger some deep-seated fear in many people.

During the 1950s, the US media introduced Americans to the concept of sensory deprivation, as a result of events during the Korean War. I haven't found any specific newspaper articles yet, but I understand that it left a lasting impression on many people. [Note: If you can direct me to any supporting material about this subject, I'd be grateful.] It may be a result of this negative exposure that many people today believe that being in a sensory deprivation tank causes a person to hallucinate or "freak out." I found a very interesting science film that illustrates this idea:

For the person who sees no difference between sensory deprivation and the floatation tank, it must be powerfully confusing for them to learn that many people pay money to spend time in a sensory deprivation tank. For these people, it's helpful to understand the significant differences between sensory deprivation as it's commonly understood, and what a sensory deprivation tank (aka floatation tank) does. 

A major part of the stress that comes from typical sensory deprivation is the extreme monotony and boredom that comes with it. It's true that our brain seeks stimulation, and that leads me to an important distinction about the sensory deprivation tank experience. When you're floating weightless in skin-temperature water that is saturated with Epsom salt, the resulting deep relaxation causes your brainwaves to gradually transition from beta (wide awake and alert) to theta, which is a dreamlike state we all experience when we're asleep. It's for this reason that the last statement made in the above video is also true of the sensory deprivation tank experience: "Deprived of normal sensory bombardment, the brain may cease to function in the usual way." The difference with the sensory deprivation tank experience is that the altered brain function has very pleasurable and beneficial effects.

Monotony and boredom isn't an issue when you're asleep because your brain isn't in the state where it's seeking constant input (beta). The same is true of being in the theta brainwave state. It typically takes 30-40 minutes to get into this theta brainwave state when you're floating in a sensory deprivation tank, but once you do reach theta, monotony and boredom are non-existent, just like when you're sleeping.

I've experienced this theta brainwave state firsthand on several dozen occasions, and I've interviewed 100s of people who have also experienced this unique state of mind. However outside of the sensory deprivation tank, the only people I know of who are able to achieve the theta brainwave state while awake are those people who are highly trained in meditation.

As always, your comments are welcome.