Does sensory deprivation tank therapy really help reduce depression and anxiety? Float therapy is an alternative treatment for mild depression and anxiety that aims to reduce stress, anxiety, depression, and even some medical conditions. But, what does science say about the benefits of short-term sensory deprivation?
In 1954, a neuropsychiatrist working for the National Institutes of Mental Health (NIMH) began experimenting with the cognitive effects of sensory deprivation. Dr. John Lilly constructed the first “isolation tank,” by filling a tank with 10 to 12 inches of water and dissolving Epsom salt in the water for buoyancy. Initially, Lilly and an NIMH colleague only performed sensory deprivation experiments on themselves. Lilly later renamed his isolation tank experiences as “Restricted Environmental Stimulation Technique” (REST).
Lilly hypothesized that subjecting the brain to sensory deprivation would cause the brain to simply “go to sleep.” However, Lilly discovered that a sensory-deprived brain engages in a high level of hyperactivity that leads to a hallucinatory altered state of consciousness. Lilly eventually became fascinated by the counterculture’s use of LSD in the 1960s and started taking psychedelic drugs before entering one of his isolation tanks.
Throughout the 1960s, isolation tanks were strictly viewed as a counterculture phenomenon meant to heighten a person’s LSD experience. It wasn’t until the early 1970s that sensory deprivation tanks became commercialized by a computer programmer named Glenn Perry. Scientists began seriously studying the effects of isolation tanks once a plethora of anecdotal evidence seemed to indicate these tanks offered psychological and physical benefits. In fact, John Lennon later claimed he relied on float therapy to help him defeat his heroin addiction.
The 1980 film Altered States introduced millions of moviegoers to the isolation tank. Although the subject of the film involved a psychopathologist using a tank to revert to the original “protohuman,” the popularity of Altered States led to a significant increase in the rentals and sales of floatation tanks. Sensory deprivation centers also began springing up in urban areas where people could pay to spend an hour inside a flotation tank.
Proponents of flotation therapy sparked the interest of neuroscientists who began using neuroimaging techniques to evaluate the brain’s activity under sensory deprivation conditions. In addition to claiming that REST provided pain relief, elevated mood, and reduced anxiety, users also said that regular one-hour sessions in a float tank helped lower their blood pressure, enhance their creativity, and improve their quality of sleep.
What Does Science Say About the Benefits of Sensory Deprivation?
The number of peer-reviewed studies conducted on the mental and physical benefits of REST is not only substantial but indicates that engaging in no more than 60 to 90 minutes of flotation therapy on an as-needed basis offers many health advantages.
A recent study funded by the Laureate Institute for Brain Research involved 50 adults with mental health disorders (PTSD, agoraphobia, and social and generalized anxiety disorder). Following a one-hour float tank session, subjects were asked about their experiences while inside the tank. Some of their descriptions included:
- “I felt out of my body but in a pleasant way.”
- “I felt detached from everything in a good way.”
- “I felt like I was floating in a sanctuary.”
- “I saw colors and lights that were relaxing and pretty.”
- “I saw light flashes resembling starbursts … it was really beautiful.”
- “I felt serene and peaceful.”
- “I felt completely refreshed like my mind and body had been reset.”
Researchers further noted a “robust” reduction in anxiety across all subgroups of anxiety disorders. Additionally, flotation therapy induced significant decreases in muscle tension, stress, depression, and general negative emotions. Subjects later reported still feeling energized, refreshed, relaxed, and peaceful.
5 Potential Benefits of Flotation Tank Therapy
Every year, millions of adults in the U.S. are diagnosed with GAD, an anxiety disorder characterized by constant worry, an inability to relax, insomnia, and feeling tired all the time. A 2016 study involving 25 people with GAD found that after twelve sessions of floatation therapy nearly 40 percent of the participants reported a “full remission” of their GAD symptoms. Results of a six-month follow-up on study subjects indicated a reduction in anxiety symptoms “had been maintained.”
Learning and Executive Thinking
Another clinically studied benefit of flotation therapy is the ability to learn more quickly and apply higher cognitive thought processes to answering test questions. A 1990 neuroimaging study found that adults who experienced 60 minutes in a sensory deprivation tank showed increased EEG activity when answering difficult questions. The non-flotation (control) group did not show the same EEG activity and had more problems answering logic-type questions.
Endorphin Release and Possible Pain Relief
A review of dozens of floatation tank studies suggests that just one session promotes the release of endorphins while lowering cortisol and adrenaline levels in the bloodstream. Elevated cortisol levels are known to contribute to the development of chronic diseases like hypertension and high cholesterol. Some subjects participating in the study reported relief of muscle tension pain, but more studies are needed to support this finding.
Positive Effects on the Circulatory System
A few studies discovered that flotation therapy helped “normalize” blood pressure, decrease blood cortisol levels and reduce mean arterial pressure in a group of young adults. These benefits could be attributed to the ability of float therapy to dilate blood vessels and improve the flow of oxygen to all areas of the body.
REST as Treatment for Addictions
Recent studies have not been conducted regarding the ability of flotation therapy to help people with substance addiction. However, one older study involving long-term smokers found that subjects receiving REST for one year were less likely to relapse than those who engaged in behavioral self-management only. Proponents of flotation tank therapy suggest that incorporating this type of therapy with a substance abuse program may help reduce cravings by providing individuals with a natural way to alleviate anxiety and achieve a sense of “relief and serenity.”
Why Do People Have Visual Hallucinations While Inside a Sensory Deprivation Tank?
Neuroscientists aren’t exactly sure why tank users often see visual hallucinations but speculate it’s due to the brain essentially having nothing else to do. The human brain has evolved to constantly perceive and interpret external stimuli for one purpose–to survive. Over millions of years of development, the brain is now successfully programmed to accept huge quantities of sensory information. In fact, the brain is so accustomed to being bombarded with sensory stimuli that when it is deprived of stimuli, it simply creates its own in the form of hallucinations.
As soon as a flotation tank user leaves the tank, hallucinations of any kind–visual, auditory, olfactory–vanish. There has never been a report of a regular tank user experiencing hallucinations outside of the tank.
How to Experience a Sensory Deprivation Tank
Most floatation tank sessions cost between $40 and $60 (for up to one hour). For the location of float tank facilities near you, this website provides information according to the city name or zip code. The website also has a video explaining what happens before, during, and after a session.