Sensory deprivation is the removal of stimuli from the senses. At the most basic level, a blindfold or earplugs are a form of sensory deprivation. In a float tank, sight and sounds are removed. The air and water are also heated to skin temperature so it becomes impossible to know where your skin ends and the water begins. And, of course, you are floating.
Floating in a tank creates the perfect conditions for removing all external stimuli. This is the sensory deprivation element. Your vision is restricted in the pitch black, you can hear nothing but your own body. You are completely buoyant in the Epsom salt water. This leads to a feeling of zero gravity with no real concept of up, down, time or space. The water and air are heated to body temperature so you are unsure where your body ends and the water begins.

FLOATATION THERAPY:
The science of sensory deprivation is known as Restricted Environmental Stimulation Therapy (REST). REST in a float tank has shown a transition from alpha or beta brainwaves to theta, which would ordinarily only occur before sleep and waking. In a flotation tank, theta brain waves occur whilst the user is fully conscious. For many users, this allows for great creativity and problem-solving. There is also evidence of physical benefits including reduced blood pressure, cortisol (the stress hormone) and improvements to blood flow. REST is also used by many athletes who claim enhanced recovery and performance.

RELAXATION:
The environment in the float tank completely isolates the senses and blocks out all distractions including gravity, temperature, touch, sight and sound. This leaves you in a deeply relaxed and meditative dream-like state like the state you enter just before you go to sleep.
Your brain uses a lot of power to deal with the strain of gravity on the body, however, in an isolation tank, your body and mind is freed from gravity so can fully relax. As a result, the brain does not need to send out any commands to the body so activity in the logical side of the brain synchronises with the creative hemisphere. This changes the brainwaves from alpha to frequency delta and theta waves, causing you to enter the meditative dream-like state whilst fully conscious.

IN THE TANK:
In the tank, you are free from external stimuli, and in a state of deep, meditative relaxation. Users in this state report a wide range of reactions and experiences: The release of tension, a heightened sense of introspection and reflection, and feeling that your mind has completely left the body are all commonly reported experiences. However, your experience will be unique to you and you may need multiple sessions to relax into the experience and feel the tank’s full effect.

HISTORY:
The flotation tank was first invented in 1954 by neuroscientist and psychologist John C Lilly to explore human consciousness. He wanted to experiment with sensory deprivation and discover what would happen if the brain was deprived of senses and all external stimulation. The first tank he invented involved wearing a diving mask to block out light and sound whilst completely submerged in an upright chamber filled with water. Lilly also experimented with psychedelic drugs whilst in the isolation tank and even claimed that the tank allowed him to make contact with creatures from other dimensions. He refined his tank in the following years and by the 1970s float tanks started to move closer towards the modern float tanks we see today. Now, the i-sopod has created a truly modern flotation tank.