Altered States: Sensory Deprivation and the Mind


Inside a sensory deprivation float tank

Imagine floating in a void abandoned by sound, absent of all light, and devoid of gravity. In this void there is no sense of up and down, left or right; the perceivable contrast between the you-internal and the world-external has faded away. In this void you are simply a plane of being—the “I” who thinks, nothing and everything all at once. This is the experience of floating in a sensory deprivation tank.

In general, consciously achieving escape from the external world is an incredibly laborious task. The strain to concentrate on nothing, and to ignore any information from the senses, is taxing. It seems to go against the very function of consciousness itself. What consciousness without any external reality to interact with, to interpret?

In 1954, neurologist and psychoanalyst John C. Lilly conceived of an experiment that would examine that very question by depriving the conscious body of nearly all sensation, essentially cutting it off from the external world. The initial sensory deprivation techniques were rather crude and bulky.


Image Credit: Lilly and Shurley, Columbia University Press

The individual was suspended in 160 gallons of water, wearing a “black-out” mask which supplied them with air and blocked any light from reaching their eyes. The water and air temperature were kept at the same temperature as the skin, roughly 90 degrees fahrenheit and most of the sound was blocked out by the water.

Over time the black-out masks were replaced with large light and sound-proof tanks that the individual climbed in to. Full body submersion was no longer required. Instead, roughly 800 pounds of epsom salt (MgSO4- 7H2O) was added at a solution density of 1.30 grams per cubic centimeter. This keeps the body perfectly buoyant.

The resulting sensation is one devoid of light, external sound, and gravity. Floating on the water’s surface makes the body feel weightless which the equal temperature to the skin makes it impossible to differentiate between the body and the water.

So what exactly happens to the mind during this particular state?

Initially, the absence of external sensory stimulation of the brain creates a vacuum into which the mind begins to seek out internal sources of stimulation (physical and/or mental). The pulsing sounds of blood flowing through the body and the rhythmic, oceanic sound of breathing can become inexorably loud. Additionally, projections of negative space—delineating the absence of an external reality—can also begin to dominate conscious awareness.1

For some, these internal projections can become too oppressive. Given enough time, however, most subjects pass through this state to the more desirable sensation of the inner mind entirely taking over where sensory perception has subsided. The mind experiences an outward expansion beyond the physical self—physicality becomes irrelevant and consciousness becomes the only apparent reality.

image_brain_activityThe experience itself can be surreal. One encounters an altered state of mind rather like returning to the womb.

This has to do with the competitive nature of brain processing. To hold and display the accepted view of reality, and to function within it, demands a great deal of attention from the brain. A careful balance must be kept between the processing of sensory information, controlling motor functions of the body, and cognition and feeling.

The fraction of mind dedicated to any one of these mental process can be expanded or contracted with respect to certain parameters. In extreme sensory situations (such as the experience of a car accident) the brain is working overtime to process all the extra sensory information and less attention is given to motor control and cognitive awareness. This is why time seems to slow down in extremely stressful situation. The opposite is true in states requiring extreme motor initiation (such as running a marathon) whereby sensory processing and cognition is diminished. This might explain how runners can “get into the zone” or “zen out” in a trance-like state of long distances.

In a sensory deprivation environment, however, the demands on the brain are maximally attenuated and the greatest possible attention is given over to cognition and emotion.

According to the literature the interpretation of this unique state of mind is largely subjective to one’s internal paradigm as well as the psychological state of the individual. Given the potential exposure of previously sheltered aspects of the self-mind to consciousness the emotional impact can vary greatly between extreme fear and absolute elation. Frankly, one is introduced to a completely naked self. The internal mind, with all of its biases and filters, is now entirely perceivable and is able to think and feel in whatever context it sees fit.

The experience is comparable to extremely deep forms of meditation.

Users report experiencing extreme states of mental relaxation and clarity, enhanced learning capacities, excited motivation and creativity, deeper insight into unconscious emotional and cognitive layers, increased post-float athletic performance, and improved injury recovery time.


A typical floatation tank

After much experimentation throughout the 60s and 70s, advocacy in literature, and pop culture references such as the film Altered States, The Joe Rogan Experience, and J.J. Abram’s Fringe, the once-esoteric practice of sensory deprivation has become readily available. Floatation centers can be found across nearly half of the United States.

Some might call the experience Nirvana while other may call it a personal Hell. What one gains from the experience is entirely open-ended. What you bring with you into the tank becomes a part of the experience. And what you come out with becomes a part of who you are.

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1. Lilly, John C. Programming and Metaprogramming in the Human Biocomputer. 2nd ed. Portland, OR: Coincidence Control, 2014. Print. (Amazon Link)

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