
An isolation tank, sensory deprivation tank, float tank, float pod, float cabin, flotation tank, or sensory attenuation tank is a water filled, pitch-black, light-proof, soundproof environment heated to the same temperature as the skin.
Method
The tank is filled with of water which contains enough dissolved
Epsom salt
Epsomite, Epsom salt, or magnesium sulfate heptahydrate, is a hydrous magnesium sulfate mineral with formula .
Physical properties
Epsomite crystallizes in the orthorhombic system. The normal form is as massive encrustations, while acicula ...
to create a
specific gravity
Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nea ...
of approximately 1.25–1.26, enabling a person to float freely with their face above the water. In order to reduce thermal sensations, the water in the float tank is maintained at approximately
skin temperature, around 35 °C. One typically floats without clothing to minimize tactile sensations, and earplugs are worn during floating both to minimize auditory sensations and to keep Epsom salt out of the ear canal.

Several different tank designs exist. Pod and cabin designs utilize enclosures with doors to enter or exit the tank, whereas pool designs are built from circular
fiberglass
Fiberglass (American English) or fibreglass (English in the Commonwealth of Nations, Commonwealth English) is a common type of fibre-reinforced plastic, fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened i ...
and lack an enclosure to reduce the risk of
claustrophobia
Claustrophobia is a fear of confined spaces. It is triggered by many situations or stimuli, including elevators, especially when crowded to capacity, windowless rooms, and hotel rooms with closed doors and sealed windows. Even bedrooms with a l ...
. The pool design is housed in a room that is soundproof and lightproof, with tightly controlled ambient air temperature and humidity.
History
The isolation tank was developed in 1954 by
John C. Lilly, a medical practitioner and
neuropsychiatrist. During his training in
psychoanalysis
PsychoanalysisFrom Greek language, Greek: and is a set of theories and techniques of research to discover unconscious mind, unconscious processes and their influence on conscious mind, conscious thought, emotion and behaviour. Based on The Inte ...
at the US
National Institute of Mental Health
The National Institute of Mental Health (NIMH) is one of 27 institutes and centers that make up the National Institutes of Health (NIH). The NIH, in turn, is an agency of the United States Department of Health and Human Services and is the primar ...
(NIMH), Lilly experimented with
sensory deprivation
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, while more complex devices can ...
.
Widespread commercial interest and use of the isolation tank did not occur until 1972, when Glenn Perry, a computer systems programmer, began selling the first commercial tanks after he attended a five-day workshop by Lilly.
In 1981, there were about $4 million in sales and rentals in the industry, and expectations were that the market would grow, spurred by the film ''
Altered States
''Altered States'' is a 1980 American science fiction horror film directed by Ken Russell, and adapted by playwright and screenwriter Paddy Chayefsky from his 1978 novel of the same name. The novel and the film are based in part on John C. Li ...
'' (a film starring
William Hurt as a psychopathologist experimenting with a flotation tank), which came out in 1980. According to one source in the industry, in the 1980s the rise of AIDS and the fear of shared water reduced demand for flotation centers.
By 2013, flotation was more popular in Europe than the US, but had undergone some growth in the area around San Francisco; at that time a low-end tank cost about $10,000, and an hour-long flotation session cost about $70.
Alternative medicine
Use of the float tank has roots in
alternative medicine
Alternative medicine refers to practices that aim to achieve the healing effects of conventional medicine, but that typically lack biological plausibility, testability, repeatability, or supporting evidence of effectiveness. Such practices are ...
,
where its use and promotion occurred largely outside of a scientific framework. Early scientific research on the use of float tanks was stalled by "political activists
hoviewed sensory deprivation as analogous to solitary confinement and torture", thus leading to "hostile publications in the popular media and in professional journals
ndto actual physical violence against researchers."
Flotation has been widely advertised as a form of alternative medicine that has a number of health benefits, but the claims are often exaggerated and poorly evidenced.
Despite the lack of scientific support, people have sought treatment from flotation for many conditions including muscle tension, chronic pain, hypertension, and rheumatoid arthritis to PMS.
Research
A 2005 meta-analysis of clinical trials that had been conducted at that time, found that the trials were generally small and highly prone to error, but given that limitation, use of isolation tanks, (called "flotation REST" or "restricted environmental stimulation therapy" in the literature) shows a large
effect size
In statistics, an effect size is a value measuring the strength of the relationship between two variables in a population, or a sample-based estimate of that quantity. It can refer to the value of a statistic calculated from a sample of data, the ...
(Cohen's d = 1.02) for
stress reduction. A 2018 review described flotation-REST as one of "
veral emerging technologies
hich
Ij () is a village in Golabar Rural District of the Central District in Ijrud County, Zanjan province, Iran
Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq ...
may have relevance for
interoception
Interoception is the collection of Sense#Other internal sensations and perceptions, senses providing information to the organism about the internal state of the body. This can be both conscious and subconscious. It encompasses the brain's process ...
and mental health" as it "appears to noninvasively enhance exposure to interoceptive sensations such as the breath and heartbeat".
Flotation-REST
Scientific research with float tank therapy generally uses the term "flotation-REST" (reduced environmental stimulation therapy) to refer to the technique.
This term is preferred over "sensory deprivation" due to the fact that 1) the float tank experience actually enhanced sensory input from the body (e.g., cardiorespiratory sensations) and can also be conceptualized as a form of sensory enhancement and 2) the term "sensory deprivation" carries negative connotations of torture and hallucinations that have likely impeded legitimate research in this field.
Notable users
*
Aaron Traywick, an American businessman and life extension activist, drowned in an isolation tank in 2018. An autopsy found evidence of
Ketamine
Ketamine is a cyclohexanone-derived general anesthetic and NMDA receptor antagonist with analgesic and hallucinogenic properties, used medically for anesthesia, depression, and pain management. Ketamine exists as its S- (esketamine) a ...
in his system.
*
Carl Lawson, football player for the
Dallas Cowboys
The Dallas Cowboys are a professional American football team based in the Dallas–Fort Worth metroplex. The Cowboys compete in the National Football League (NFL) as a member of the National Football Conference (NFC) NFC East, East division. T ...
, and formerly the
New York Jets
The New York Jets are a professional American football team based in the New York metropolitan area. The Jets compete in the National Football League (NFL) as a member of the American Football Conference (AFC) AFC East, East division. The team p ...
and
Cincinnati Bengals
The Cincinnati Bengals are a professional American football team based in Cincinnati. The Bengals compete in the National Football League (NFL) as a member of the American Football Conference (AFC) AFC North, North division. The team plays its h ...
, uses the tank for muscle recovery and visual training.
*
Carl Lewis
Frederick Carlton Lewis (born July 1, 1961) is an American former track and field athlete who won nine Olympic gold medals, one Olympic silver medal, and 10 World Championships medals, including eight gold. Lewis was a dominant sprinter and lo ...
, track and field athlete, used in-tank visualization techniques to prepare himself for his gold medal long jump at the 1988 Seoul Olympics.
* During
Super Bowl XLIX
Super Bowl XLIX was an American football game played to determine the champion of the National Football League (NFL) for the 2014 NFL season, 2014 season. The American Football Conference (AFC) champion 2014 New England Patriots season, New Eng ...
, both NFL teams (the New England Patriots and Seattle Seahawks) rented out a local float spa during the week of the event. One team would float in the morning and the other would float in the afternoon.
*
Christof Koch
Christof Koch ( ; born November 13, 1956) is an American cognitive scientist, neurophysiologist and computational neuroscientist best known for his work on the neural basis of consciousness. He was the president and chief scientist of the All ...
, a neuroscientist known for his work on consciousness, states that he had "what some people call a mystical experience" in a float tank in Singapore.
*
Joe Rogan
Joseph James Rogan (born August 11, 1967) is an American podcaster, Ultimate Fighting Championship, UFC color commentator, comedian, actor, and former television host. He hosts The Joe Rogan Experience, ''The Joe Rogan Experience'', which is o ...
has stated in his podcast on numerous occasions that he owns an isolation tank and credits it for allowing a state of deeper meditation.
*
John Lennon
John Winston Ono Lennon (born John Winston Lennon; 9 October 19408 December 1980) was an English singer-songwriter, musician and activist. He gained global fame as the founder, co-lead vocalist and rhythm guitarist of the Beatles. Lennon's ...
treated his heroin addiction in 1979 with the help of 90-minute floats in a cedar-wood box.
*
Marvin Jones, wide receiver for the
Jacksonville Jaguars
The Jacksonville Jaguars are a professional American football team based in Jacksonville, Florida. The Jaguars compete in the National Football League (NFL) as a member of the American Football Conference (AFC) AFC South, South division. The team ...
and formerly of the
Cincinnati Bengals
The Cincinnati Bengals are a professional American football team based in Cincinnati. The Bengals compete in the National Football League (NFL) as a member of the American Football Conference (AFC) AFC North, North division. The team plays its h ...
and
Detroit Lions
The Detroit Lions are a professional American football team based in Detroit. The Lions compete in the National Football League (NFL) as a member of the National Football Conference (NFC) NFC North, North division. The team plays their home game ...
, began using flotation therapy to help him in his recovery from an ankle injury while in Cincinnati.
*
Phil Lester visited a flotation center for a YouTube video on his channel "AmazingPhil" on February 17, 2020.
*
Richard Feynman
Richard Phillips Feynman (; May 11, 1918 – February 15, 1988) was an American theoretical physicist. He is best known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics, the physics of t ...
, Nobel Prize-winning physicist, discussed his experiences with isolation tanks in ''
Surely You're Joking, Mr. Feynman!''
* Several NFL teams, including the
New England Patriots
The New England Patriots are a professional American football team based in the Greater Boston area. The Patriots compete in the National Football League (NFL) as a member of the American Football Conference (AFC) AFC East, East division. The Pa ...
,
Los Angeles Rams
The Los Angeles Rams are a professional American football team based in the Greater Los Angeles, Greater Los Angeles area. The Rams compete in the National Football League (NFL) as a member of the National Football Conference (NFC) NFC West, West ...
, and
New Orleans Saints
The New Orleans Saints are a professional American football team based in New Orleans. The Saints compete in the National Football League (NFL) as a member of the National Football Conference (NFC) NFC South, South division. Since 1975, the team ...
reportedly use floating as a way to increase players' quality of sleep as well as help with recovery.
* In 2015 two-time
NBA MVP Stephen Curry
Wardell Stephen Curry II ( ; born March 14, 1988) is an American professional basketball player and point guard for the Golden State Warriors of the National Basketball Association (NBA). Nicknamed "Chef Curry", he is widely regarded as the ...
reportedly used a sensory-deprivation tank every two weeks.
See also
*
Dark retreat
Dark retreat (Allione, Tsultrim (2000). ''Women of Wisdom''. (Includes transcribed interview with Namkhai Norbu) Source(accessed: November 15, 2007)) is a spiritual retreat in a space that is completely absent of light, which is an advanced pract ...
*
Mindfulness
Mindfulness is the cognitive skill, usually developed through exercises, of sustaining metacognitive awareness towards the contents of one's own mind and bodily sensations in the present moment. The term ''mindfulness'' derives from the Pali ...
*
Prisoner's cinema
*
Psychedelic experience
A psychedelic experience (known colloquially as a trip) is a temporary altered state of consciousness induced by the consumption of a psychedelic substance (most commonly Lysergic acid diethylamide, LSD, mescaline, psilocybin mushrooms, or N,N- ...
References
{{DEFAULTSORT:Isolation Tank
Alternative medical treatments
Experimental psychology
Devices to alter consciousness