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Sensory deprivation or perceptual isolation is the deliberate reduction or removal of stimuli from one or more of the senses. Simple devices such as blindfolds or hoods and earmuffs can cut off sight and hearing respectively, while more complex devices can also cut off the sense of smell, touch, taste, thermoception (heat-sense), and 'gravity'. Sensory deprivation has been used in various alternative medicines and in psychological experiments (e.g., see Isolation tank).

Short-term sessions of sensory deprivation are described as relaxing and conducive to meditation, if sometimes boring; however, extended or forced sensory deprivation can result in extreme anxiety, hallucinations, bizarre thoughts, depression and death.

Restricted Environmental Stimulation Therapy (REST)

Chamber REST

There are two basic methods of restricted environmental stimulation therapy (REST), chamber REST and floatation REST. In chamber REST, subjects lie on a bed in a completely dark and sound reducing (on average, 80 dB) room for up to 24 hours. Their movement is restricted by the experimental instructions, but not by any mechanical restraints. Food, drink and toilet facilities are provided in the room and are at the discretion of the tester. Subjects are allowed to leave the room before the 24 hours are complete, however fewer than 10% actually do.

Flotation REST

In floatation REST, the room contains a tank or pool. The floatation medium consists of a skin-temperature solution of water and Epsom salts at a specific gravity that allows for the patient to float supine without worry of safety. In fact, to turn over while in the solution requires “major deliberate effort.” Fewer than 5% of the subjects tested leave before the session duration ends, which is usually around an hour for flotation REST.

For the first forty minutes it is reportedly possible to experience itching in various parts of the body (a phenomenon also reported to be common during the early stages of meditation). The last 20 minutes often end with a transition from beta or alpha brainwaves to theta, which typically occur briefly before sleep and again at waking. In a float tank the theta state can last for several minutes without the subject losing consciousness. Some use the extended theta state as a tool for enhanced creativity and problem-solving or for superlearning. Spas sometimes provide commercial float tanks for use in relaxation. Flotation therapy has been academically studied in the USA and in Sweden with published results showing reduction of both pain and stress. The relaxed state also involves lowered blood pressure and maximal blood flow.

Statistical Data

Numerous studies have debated which method is a more effective treatment process, however, only one has explored this statistically. 19 subjects, all of whom used chamber and/or floatation REST to induce relaxation and/or treat smoking, obesity, alcohol intake or chronic pain were analyzed. The statistic of interest, d, is a measure of the size of the treatment effect. For reference, d=0.5 is considered a moderate effect and d=0.8 a large effect. The 19 subjects who underwent chamber REST had d=0.53 and 6 flotation REST subjects showed d=0.33. Additionally, when examining subjects undergoing REST treatment and REST in conjunction with another treatment method, there was little difference

Differences between chamber and flotation REST

Several differences exist between flotation and chamber REST. For example, with the presence of a medium in flotation REST, the subject has reduced tactile stimulation while experiencing weightlessness. Additionally, the addition of Epsom salts to attain the desired specific gravity may have a therapeutic effect on hypertonic muscles. Since one of the main effects of chamber REST has been the resulting state of relaxation, the effects of chamber REST on arousal are less clear-cut, which can be attributed to the nature of the solution.

Second, due to the inherent immobilization that is experienced in flotation REST (due to not being able to roll over), which can become uncomfortable after several hours, the subject is unable to experience the session durations of chamber REST, which may not allow the subject to experience that changes in attitudes and thinking that are associated with chamber REST.

Third, the research questions asked between each technique are different. Chamber REST questions stemmed out of research that began in the 1950s and explored a variety of questions about the need for stimulation, nature of arousal and its relationship with external stimulation. Practitioners of this explored its utility in the treatment of major psychiatric dysfunctions such as autism and substance misuse. On the contrary, flotation REST was seen as more of a recreational tool as it was tested more for its use with stress-related disorders, pain reduction and insomnia.

Other Uses

The use of REST has been explored in aiding in the cessation of smoking. In studies ranging between 12 months and 5 years, 25% of REST patients achieved long term abstinence. REST, when combined with other effective smoking cessation methods (for example: behavior modification), resulted in long term abstinence of 50%. Lastly, when combined with weekly support groups, REST resulted in 80% of patients achieving long term abstinence. Comparatively, the use of the nicotine patch alone has a success rate of 5%.

Alcoholism has been the target of research associated with REST. In conjunction with anti-alcohol educational messages, patients who underwent 2 hours of REST treatment reduced alcohol consumption by 56% in the first two weeks after treatment. The reduction in consumption was maintained during follow-ups conducted 3 and 6 months after first treatment.

Results from a study conducted by Washington State University are listed in the table below.
Alcohol Consumption (oz/day)
Prior to REST 42.7
Immediately post-REST 23.3
3 months post-REST 16.0
6 months post-REST 12.7

Lastly, REST has been tested to determine its effect on drug abusers. A University of Arizona study used chamber REST as a complement to traditional outpatient substance abuse treatment and found that 43% of the patients after 4 years continued to be sober and drug-free. No one in the control group remained clean after 8 months.

Negative Effects

Studies have been conducted to test the effect of sensory deprivation on the brain. One study took 19 volunteers, all of whom tested in the lower and upper 20th percentiles on a questionnaire which measures the tendency of healthy people to see things not really there, and placed them into a pitch black, soundproof booth for 15 minutes. After, they completed another test, which measures psychosis-like experiences which was originally used to study recreational drug users. Five people reported seeing hallucinations of faces, six reported seeing shapes/faces not actually there, four noted a heightened sense of smell and two people reported sensing a "presence of evil" in the room. Not surprisingly, people who scored lower on the first test experienced fewer perceptual distortions, however, still reported seeing a variety of delusions and hallucinations.

The cause of the hallucinations is up to debate, however, there are two main theories that exist. First, it's thought that sensory deprivation has an effect, which is very similar to ketamine or cannabis in being psychosis-inducing. These studies were also the first to suggest the idea that sensory deprivation can lead to symptoms of psychosis. Second, it's believed that psychosis occurs in sensory deprivation chambers because the brain misidentifies the source of what it is currently experiencing, a phenomenon called faulty source monitoring.

José Padilla

See: José Padilla
Jose Padilla at the Navy Consolidated Brig.
Padilla was convicted of aiding terrorists in 2007 and was sentenced to 17 years, 4 months in prison. While awaiting trial, reports surfaced that he was being tortured for information with the use of sensory deprivation for weeks at a time. For 1,307 days, Padilla was kept in a 9' x 7' cell with no natural light, clock and calendar. Whenever Padilla left his cell, he was shackled and fitted with heavy goggles and headphones. His counsel argues that while he was being interrogated Padilla was subjected to harsh lights and pounding sounds. While meeting with his counsel, they reported Padilla exhibiting facial tics, random eye movements and unusual contortions of his body. According to them, Padilla had become so "shattered" that he became convinced his lawyers were part of a continuing interrogation program and saw his captors as protectors.

"Total Isolation"

In January 2008, the BBC aired a special entitled "Total Isolation." The premise of the show centered around 6 individuals who agreed to be shut inside a cell in a nuclear bunker, alone and in the dark. Prior to isolation, the volunteers underwent tests of visual memory, information processing, verbal fluency and suggestibility. After, they spent two days and two nights in isolation. The subjects noted that their inability to sense time and the hallucinations and visions that they experienced made the 48 hours inside the cell very difficult on their mind.

Of the six volunteers, two coped well. One woman was convinced her sheets were wet. Three experienced auditory and visual hallucinations - snakes, oysters, tiny cars and zebras. After the 48 hours was complete, the same tests were conducted. The results indicated that the volunteers' ability to complete the simplest tasks had deteriorated. One subject's memory capacity fell 36% and all the subjects had trouble thinking of words beginning with the letter "F". All four of the men (neither of the two women) had markedly increased suggestibility.

"Its really hard to stimulate your brain with no light.

It's blanking me.

I can feel my brain just not wanting to do anything."

—Adam Bloom, "Total Isolation"

In popular culture


  • The Tom Clancy novel The Cardinal of the Kremlin features the descriptive use of a sensory deprivation device by the KGBmarker in brainwashing techniques for counterintelligence purposes.
  • In the book by George Orwell, Nineteen Eighty-Four, sensory deprivation and its possibly mind-twisting effects are very well described in the second half of the story.
  • Arthur Koestler's book, Darkness at Noon, describes sleep deprivation practices during and between interrogations in the 1938 Soviet Union.
  • In the Larry Niven novel A Gift from Earth, a sensory deprivation tank is used as an interrogation device; in the story it is referred to as "the coffin cure".
  • In the H. Beam Piper novel Little Fuzzy, a Company psychologist, Dr. Ernst Mallin, used a sensory deprivation tank on a group of Fuzzies by way of determining how their cognitive functioning differed from humans. Each of the Fuzzies in turn entered a yoga-like state that defeated the effects of the deprivation tank.
  • In the Marvel Comics series The ClanDestine, Dominic Destine, who has senses that dwarf even those of Daredevil, when living on his family estate, would spend his time in an anechoic chamber, a sort of sensory deprivation room. He eventually came to wear an isolation shell generator, which creates anti-stimulation aura, as a sort of portable anechoic chamber.
  • Irish author John McGuffin wrote a provocative book, entitled The Guineapigs, documenting the chilling accounts of 14 Irish political detainees held by the British Army over an eight-day period during which they were subjected to extreme sensory deprivation. The accounts are graphic, intense and shocking. The first edition, published in 1974, sold 20,000 copies and was banned by the British government after one week on the shelves.
  • Dean Koontz's The Door to December is about a father who subjects his kidnapped daughter to prolonged periods in a sensory deprivation chamber in order to awaken psychic abilities.
  • In Dean Koontz's The Husband, there are a few sections relating to a man who was subjected to prolonged periods in a sensory deprivation room, to increase learning. The room is given the name "the learning room".
  • In the book Psychic Warrior by Robert Doherty, the protagonists are placed in sensory deprivation chambers in preparation for their missions, in order to allow their mind to focus on the "distant present."
  • In the third book The Passion of fantasy-series Dark Visions by Ljane Smith, a sensory deprivation chamber is used to torture the protagonist, Kaitlyn Fairchild.
  • In the 1967 science fiction novel by Philip K. Dick and Ray Nelson, The Ganymede Takeover, alien collaborator and psychiatric genius Rudolph Balkani uses the sensory deprivation tank to break resistance sympathizer Joan Hiashi.
  • In the book Tales of Pirx the Pilot by Stanisław Lem, in the chapter The Conditional Reflex, the main character is put to the test known among students as "The Bath", in which the subject (the student) must lay down completely submerged in a pool of salt water, that is heated to such temperature that he cannot feel it anymore. The subject has a mask on his head, that deprives him of smell, hearing and sight. The student has to stay in the water for as long as possible. Any movement or sound made by the student earns him penalty points.
  • In the book Quiller Barracuda by Adam Hall, a description of hooding is provided by the main character in the chapter "Breakthrough".
  • In the book Maximum Ride: School's Out Forever by James Patterson, the main character is kept in a sensory-deprivation tank in an attempt to break her spirit.
  • In the book The Lost Symbol by Dan Brown, Robert Langdon is immersed in a sensory-deprivation tank by the main antagonist, Mal'akh. Readers and other characters in the book believe he has drowned and is starting to experience the afterlife, but later the truth is revealed that he is breathing oxygenated liquid.
  • In the Japanese manga Planetes, an isolation chamber is used to examine the mental stability of potential astronauts.
  • In The Superman movies, books, and comicbooks, Superman periodically retreats alone for meditation to the so called 'Fortress of Solitude', which could be interpretted as a kind of sensory deprivation chamber, or even psychomantium, for purposes of achieving greater mental focus and clarity in problem solving, or, to contact his father for advice.


  • The Ipcress File (1965), starring Michael Caine, featured a variation on sensory deprivation in the final scene.
  • Altered States (1980), starring William Hurt, Blair Brown and Bob Balaban. Based on the novel by Paddy Chayefsky.
  • In the film Simon (1980), Alan Arkin, who plays the title character, is placed in a sensory deprivation tank and left for several days by scientists who want to brainwash him into believing he is an alien. When he finally comes out of the tank, Arkin performs a pantomime that represents evolution, from primordial ooze to modern man.
  • In the superhero film Daredevil (2003), the eponymous Marvel Comics character, Matt Murdock (Ben Affleck) sleeps in a sensory-deprivation chamber. Because of Murdock's heightened senses, the water in the tank helps to drown out any sound or touch.
  • In the film The Jacket (2005), Adrien Brody is placed in an improvised sensory deprivation tank as a part of his rehabilitation treatment. The deprivation tank is an important plot element.
  • The Mind Benders (1962) Starring Dirk Bogarde, Mary Ure & John Clements. After the suicide of a colleague suspected of being a Soviet spy, Dr. Henry Longman (Bogarde) undergoes sensory deprivation in an attempt to clear his friends name.
  • In the film Shortbus (2006), one of the lead characters, Sofia (Sook-Yin Lee) visits a spa with a sensory deprivation tank to meet with Severin to explore her inability to achieve an orgasm.


  • In many TV-quiz, participants wear headphones and listen music, so they can´t hear right answer before their own turn.
  • In the television series 24, government agents have used sensory deprivation as a method of interrogation.
  • In Family Matters, Steve Urkel is said to have a sensory deprivation tank. Laura states that she can hear him sobbing from his sensory deprivation tank.
  • The 1960s television show The Twilight Zone featured an episode in which an astronaut spent weeks in a secluded chamber in order to simulate a trip to the moon, leading to hallucinations.
  • In the 1968 pilot to the television series Hawaii Five-O, "Cocoon", Red Chinese agent Wo Fat uses a sensory deprivation chamber to procure information from U.S. agents.
  • In the television series Alias starring Jennifer Garner, sensory deprivation was used on CIA agent Sydney Bristow by The Covenant in order for them to brainwash her into thinking she was someone she was not.
  • In the Simpsons episode "Make Room for Lisa", Lisa and Homer go to an alternative medicine specialist that recommends they spend time in sensory deprivation tanks.
  • The TV series Earth: Final Conflict features sensory deprivation prisons, where inmates float in an oxygenated fluid, completely deprived of all sensory stimuli.
  • The use of, and mention of, a sensory deprivation tank occurred on several early episodes of Frasier. It was one of Maris' few hobbies.
  • In the TV series Fringe, FBI agent Olivia Dunham, played by Anna Torv, is placed in a sensory tank in order to connect her mind with another dying, comatose character. Later, she uses the tank to connect with the other characters memories that had left an imprint in her mind.
  • In a season four episode of House ("House's Head"), Dr. Gregory House undergoes sensory deprivation while trying to solve a medical mystery.
  • In the episode "Iso Tank" of the TV series Absolutely Fabulous, Eddie and Patsy are in the iso tank while Eddie dreams of her life with a few twists. At the end of the episode, Eddie gets rid of the tank after finding out that she isn't the only one in Britain that has one.
  • In the anime, Serial Experiments Lain, the episode "Protocol" references John C. Lilly and the use of sensory deprivation tanks.


  • There is a song named "Sensory Deprivation Adventure" on the album Holding A Wolf by the Ears by American metalcore/post-hardcore band From Autumn to Ashes.
  • Industrial metal band Cyanotic have a song entitled "Sensory Deprivation" on their 2005 album Transhuman.
  • The Who's Tommy tells the story about a boy who is robbed of his senses due to a traumatic event. He then regains his senses, forms a cult, in which the people are to wear special lenses that are completely black. They also have earplugs and a cork for the mouth. He does this so people can better understand what he went through.

See also


  • European Court of Human Rights and in a landmark judgement "Ireland v. the United Kingdom" January 18, 1978
  • Solomon, P. et al. (eds.) (1961) Sensory deprivation. Harvard U Press.
  • Goldberger, L.(1966). Experimental isolation: An overview. Am. J. Psychiat. 122, 774-782.
  • Zubek, J. (ed.) (1969). Sensory deprivation: Ffiteen years of research. Appleton Century Crofts.


Further reading

  • Goldberger, L. Experimental isolation: An overview. Amer. J. Psychiat., 1966, 122, 774-782.
  • Heron, W. The pathology of boredom. Sci. Amer, 1957, 196, 52-56.
  • John Lilly, (inventor of the flotation tank),"The Deep Self: Profound Relaxation and the Tank Isolation Technique" (See also John Lilly, in Flaherty, B.E. (Ed) Psychophysiological aspects of space flight, Columbia U Press, 1961)
  • Solomon, P. et al. (eds.) (1961) Sensory deprivation. Harvard U Press.
  • Suedfeld, P. (1980). Restricted environmental stimulation: Research and clinical applications. Wiley Interscience.
  • Zuckerman, M., et al. Experimental and subject factors determining responses to perceptual and social isolation. J. abnorm. Psychol. 1968, 73, 183-194.
  • Zubek, J. (Ed.) 1969) Sensory deprivation: Fifteen years of research. Appleton Century Crofts.
  • By the Numbers Findings of the Detainee Abuse and Accountability Project Report of the Detainee Abuse and Accountability Project (26 April 2006).

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