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Sensory Deprivation

Chandni Dwivedi Jul 17, 2020
Feeling excessively stressed-out lately? Sensory Deprivation, a technique used for meditation and relaxation, could come to your rescue.
For long, it was assumed that the brain, without sensory stimulation, would pop off to sleep. But pioneering research by Dr. John C. Lilly in 1954, proved otherwise. His research provided the foundation for further study into sensory deprivation.

What is Sensory Deprivation?

Sensory deprivation means depriving the brain of sensory stimuli (from light, sound, smell, and touch) by way of prolonged isolation in a dark room.
If this technique is used for short periods of time, it can help in meditation and relaxation, but if it is used excessively and for long periods, it can induce hallucinations, depression, anxiety, or bizarre thoughts. It is increasingly being used as a form of alternative medicine, because of its potential to enhance mental and physical well-being.


Sensory deprivation is also known as Restricted Environmental Stimulation Therapy (REST). This technique cuts-off or minimizes all external sense stimuli of light, sound, smell, and touch. Two of the commonly used methods are -
#1 - Chamber REST: In this method, subject lies on a bed in a completely dark room with a very low-noise environment, for upto an hour. There are movement restrictions on the subject, though food, drink, and toilet facilities are provided. The subject may need to wear translucent goggles that let in light, but prevent seeing definite shapes and patterns.
In addition, cardboard cuffs and cotton gloves have to be worn to reduce the sense of touch, and U-shaped pillows are kept around the head to block out most sounds. Chamber REST results in a state of relaxation; however, it has been observed that just 15 minutes of this can bring about hallucinations in some individuals.
#2 - Flotation REST: This method was devised by Dr. John C. Lilly in 1954. It includes the use of a flotation tank containing water mixed with Epsom salt at a specific gravity, which lets the subject's body float in a supine position without sinking. The water temperature is kept same as that of the subject's skin.
The flotation tank is a light-less and soundless room. This is done to cut-off all sensory stimuli and induce a weightless state. According to Dr. Lilly, external stimuli of gravity, light, sound, and touch accounted for 90% of the central nervous system's workload.
By reducing the excess external stimuli, a person's stress levels can be significantly reduced. Free from the pull of gravity, every muscle in the body can relax. These sessions usually last for about an hour.


By eliminating the external sensory stimuli, this technique reduces the central nervous system's workload. The brain relaxes into a theta state (A dream-like state commonly experienced just before falling asleep) and more endorphins are released into the bloodstream. 
Increased levels of endorphins produce a happy state of mind and feeling of well-being. It also makes the brain smarter and more efficient, enables a person to process information more clearly and improves concentration as well as creativity. It is useful in easing various aches and pains plaguing the body.
Flotation REST is useful for those trying to quit smoking and alcohol as well as relieves anxiety symptoms and depression. The Epsom salts are beneficial in reducing swelling and ease muscle tension. One hour of Flotation REST provides benefits similar to four hours of sleep.

Harmful Effects

Prolonged sensory deprivation can lead to extreme disorientation, poor problem-solving ability, depression, hallucinations, paranoia, and severe anxiety. Perceptions can get distorted and brain-wave patterns which become slow during the procedure, take many hours to return to normal.
All of this happens because human beings require an optimal level of arousal. Too less of it, therefore, can dull the senses. Prolonged sensory deprivation is used as a form of torture by police forces. It is not recommended for those who suffer from claustrophobia or have a fear of dark, or enclosed spaces.
Finally, sensory deprivation is a controlled experiment that attempts to calm and clear the mind by reducing the load of sensory perceptions. This is achieved by artificially creating an environment devoid of light, sound, smell and, sometimes, gravity, thus freeing up a person's mind and enabling him/her to experience calmness, silence, and peace.