A sensory deprivation tank is a temperature-regulated, light-proof tank that is filled with salt water. Its purpose is to isolate the user from all forms of sensory input at once. Throughout history there have been many different types of sensory deprivation designs, but the modern incarnation, the sensory deprivation tank, is essentially a standalone pod that serves to isolate people from sensory experience.
Isolation tanks have been useful in treating certain chronic pain conditions like musky low skeletal pain, motion disorders like headaches, as well as hypertension
Sensory deprivation tanks owe their creation to a neuroscientist named John C. Lilly. Lilly experimented with sensory deprivation by suspending people in 160 gallons of water with all but the very top of the individual’s head submerged. Participants wore a mask that effectively covered the head and blocked out light from reaching their eyes.
The water temperature was regulated to be the same temperature as your skin which was roughly 34°C. Eventually this approach was modernized and sensory deprivation tanks came into being- instead of being submerged in water, 800 pounds of epsom salt are included in the tank so that users float on the surface of the water.
Inside of the tank, floating on this water, you experience a profound quiet. You can hear your heartbeat, as well as your eyelids open and close. The epsom salts lends the floating effect to the experience, making it feel as though you were in a zero gravity chamber, like floating in space. As well, since the water is temperature controlled, you lose the ability to perceive where your body ends in the water and surrounding area begins.
Lilly was a profound advocate of sensory deprivation chambers and claims that his own experiences in these tanks enabled him to make contact with extra-dimensional creatures and civilizations that were far more advanced than humanity.
This first encounter with these extra-dimensional entities he described as “the first conference of three beings“.
The more common descriptions of the experience include hallucinations, enhanced introspection, and out of body experiences. In some ways, it seems that sensory deprivation chambers are a way to fast track the experience of profound meditative contemplation.
Individuals that are highly experienced meditators describe similar experiences to people using sensory deprivation tanks for the first time. Both meditators and tank users experienced decreased alpha waves as well as increased theta waves- these patterns are most typically seen during sleep.
Research has shown that even 15 minutes of sensory deprivation can produce temporary hallucinations. For instance the appearance of faces or shapes, smells that are not actually there, or even a feeling of an evil presence.
In general, however, most people who experience sensory deprivation tanks have the urge to try them over and over again because of their calming and introspective effects.
Some research studies have demonstrated that isolation tanks have been useful in treating certain chronic pain conditions like musculoskeletal pain, motion disorders like headaches, as well as hypertension. As well, sensory deprivation has been shown to have positive effects on insomnia, as well as eating and the cessation of smoking.
Its positive effects, which can include feelings of a Zen-like state, may explain why people experience pain relief from reductions in stress and tension.