John C. Lilly, a medical practitioner and neuro-psychiatrist, developed the floatation tank in 1954. During his training in psychoanalysis at the US National Institute of Mental Health (NIMH), Lilly commenced experiments with sensory deprivation. In neurophysiology, there had been an open question as to what keeps the brain going and the origin of its energy sources. One hypothesis 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 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.
Initial isolation tanks were uncomfortable, people were required to wear complicated head-masks to breathe underwater, and tight clothing that constricted the blood flow in certain areas detracted from the isolation experience. In newer tanks, epsom salt is added to increase the density of the water so that the user floats with the face above the water. However, since the ears are submerged when the subject is in a 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. The density of the water prevents rolling over, even if asleep.
By now few are unaware that the activity of the human brain creates patterns of electrical energy, that the electrical signals of the brain can be monitored by placing electrodes against the scalp, and that a device known as an electroencephalograph (or EEG ) can record the brain waves by means of a sensitive mechanical pen tracing, across a long sheet of paper, a mountain range of jagged lines — as immortalized in a thousand science fiction movies and television hospital series. Flat line equals brain death - cart him away, nurse.
These brain signals have a tendency to fall into certain patterns which scientists have classified in four types:
When the brain is generating mostly beta waves, whose frequency is about 13-30 Hz ( that is, a rhythm of 13 to 30 cycles per second ), it is in what is called its waking rhythm: The brain is focusing on the world outside itself, or dealing with concrete, specific problems.
As the brain waves slow down they take on a more coherent rhythm, and can be seen on the EEG as a regular sawtooth pattern at about 8 - 12 Hz. These waves are often present when the brain is alert but unfocused, and most people generate alpha waves when their eyes are closed, even if only bursts of one or two seconds. Frequently, alpha waves are associated with feelings of relaxation and calmness.
As calmness and relaxation deepen into drowsiness, the brain shifts to slower, more powerfully rhythmic waves with a frequency of about 4 -7 Hz. Everyone generates these theta waves at least twice per day: in those fleeting instants when we drift from conscious drowsiness into sleep, and again when we rise from sleep to consciousness as we awaken. The theta state is accompanied by unexpected, unpredictable, dreamlike but very vivid mental images (known as the hypnagogic images ). Often these startlingly real images are accompanied by intense memories, particularly childhood memories. Theta offers access to unconscious material, reverie, free association, sudden insight, creative inspiration. It is a mysterious, elusive state, potentially highly productive and enlightening, but experimenters have had a difficult time studying it, and it is hard to maintain, since people tend to fall asleep as soon as soon as they begin generating large amounts of theta.
Cycling at an extremely slow frequency (.5-4 Hz), delta rhythms are produced when people are deeply asleep or otherwise unconscious. Throughout the 1960s, experimenters discovered that with the use of equipment that electrically monitored selected physical functions, humans could learn to generate those functions at will. While biofeedback equipment could be made to monitor just about any physical function, researchers often focused on the production of alpha waves. Stress was a problem shared by almost everyone, and an accepted antidote to stress was relaxation; since alpha waves accompanied relaxation, and were relatively easy to learn to produce at will, clinical biofeedback experts assumed that if you learn to generate alpha waves, you would automatically become relaxed. In the early 1970s, with the advent of relatively inexpensive equipment came an explosion of interest in biofeedback, and alpha became the catchword seized on by the mass media and seekers of expanded consciousness.