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Sensory Deprivation Therapy

sensory deprivation therapy

Imagine floating in a perfectly safe, quiet environment. Your mind wanders. Daydreams emerge. Thoughts coalesce. Suddenly, the answers to problems pop into your mind. You feel relaxed yet energized as you emerge refreshed from the sensory deprivation tank.

Tanks designed for sensory deprivation were invented in the 1950s but were not widely used until the 1970s. Since the 1970s, the concept has caught on with people interested in health and wellness worldwide. Spas and resorts offer sensory deprivation tanks. There are even float tanks available for home use.

Sensory deprivation has been likened to yoga, meditation and other calming, centering exercises. It helps people relax and de-stress. Once external sounds and other stimuli are eliminated, stress melts away.

The History of Sound Deprivation Therapy

Sound deprivation therapy developed out of sensory deprivation experiments in the Cold War. It sounds perverse, but it began as an exploration of what happens to prisoners of war when subjected to overstimulation of the senses. In the 1950s, research was conducted at McGill University to see what happened when the senses were overstimulated, according to Discover Magazine.

This to scientists to wonder what would happen when the senses were blocked — that is, when all light, sound, smell, taste and touch are blocked. They found sensory deprivation was a pleasant and sometimes even mind-altering experience for some people.

In 1997, researchers analyzed over 1,000 descriptions of sensory deprivation to assess the experience. Over 90 percent of participants found the experience deeply relaxing, Discover Magazine reports.

Today, sound or sensory deprivation therapy is used for people suffering from anxiety and stress. Many prefer resting in a sensory tank to participating in yoga or meditation. People report similar feelings of peace, wellness and rest after experiencing a sensory tank as when they participate in other meditative experiences.floating sensory deprivation

Types of Sensory Deprivation Experiences

Sensory deprivation today has been renamed REST, short for Restricted Environmental Stimulation Therapy. Two types of REST are commonly available — flotation and chamber REST.

Chamber REST

Chamber rest relies upon similar principles as flotation rest but does not use water. In a chamber REST session, participants enter a room that has a bed, toilet facilities, and food and drink. They lie on a bed in a soundproof, darkened room for up to 24 hours. Chamber REST sessions do not give participants the sense of weightlessness flotation provides, but other respects offer similar benefits.

Flotation REST

Flotation REST is based on the pioneering work of Dr. John Lilly in the 1970s. The pod or tank is big enough so participants can stretch out, move their arms, and float inside. Each tank is filled with 98-degree water. Epsom salts are added to plain water, or salt water is used to enhance flotation. Users place soft foam earplugs in their ears to block sound. After entering the tank, the hatch is closed, and all sense of time, space and sensation are gone.

The tank itself blocks out light. They are constructed to block sound, but the earplugs also help block out any excess sound. Salt water helps buoyancy, and Epsom salts relax the muscles. Warm water the same temperature as the human body helps the floater feel at one with the water. The entire experience is serene, comforting and womb-like.

The experience can be unsettling at first, although you can terminate the session at any time. Most people report hallucinations behind their closed eyelids — geometric patterns, lights, or dots the brain conjures in response to the lack of stimulation. Less common but also possible are auditory hallucinations.

Flotation REST sessions typically last about 60 to 90 minutes.

How Does REST or Sensory Deprivation Affect the Brain?

REST or sensory deprivation provides people with a sense of deep relaxation. As people slip into this state of deep relaxation, the brain does some amazing gymnastics that create sensory hallucinations.

During sensory deprivation, people report hallucinations of lights or sounds. While not unpleasant, these experiences can be startling if you’re not prepared for them.

In one experiment, volunteers underwent a process like chamber REST. McGill University tested undergraduate students in the mid-1950s to determine the effects of sensory deprivation on the brain.

The students entered a soundproof room with a comfortable bed. They wore goggles to diffuse visual input, and researchers taped foam pillows around the students’ heads to prevent any sounds from reaching their ears. They laid down on a comfortable bed and their arms were encased in foam pillows. During the test, they could only rise to use the bathroom or to eat during schedule meal breaks.

sensory deprivation tank hallucinations

Surprising Impact of Sensory Deprivation

Researchers were surprised when many volunteers quit the experiment after only two days. The longest any volunteer remained in the experiment was six days. The volunteers reported the followed occurred during sensory deprivation:

  • At first, patterns of light appeared before their eyes. Points of light, lines and geometric patterns were most frequently reported.
  • Next, the patterns organized themselves into repeated patterns. The experimental subjects described this as similar to patterns of lines and designs on wallpaper or wrapping paper.
  • Lastly, the abstract designs turned into bizarre yet realistic images. Volunteers reported seeing things like squirrels marching along a road with sacks over their shoulders, a procession of eyeglasses, and other animals and scenes playing out in their minds’ eyes.
  • The longer the volunteer lasted in sensory deprivation, the more intricate the scenes became, although not everyone saw the same thing. A few volunteers heard sounds like choirs singing or people talking. One volunteer reported reaching out in his daydream to open a door and feeling an electric shock go down his arm.

What fascinated the researchers at McGill is how the brain’s normal output transforms when the senses are blocked. During everyday life, your brain is constantly sending impulses and signals to different parts that manage memory, sight, hearing and other senses. It’s experiencing, recording and organizing information, and preserving it as short-term and long-term memory.

When the senses are blocked, the brain continues its work. The electrical impulses that normally go undetected during an average day are suddenly thrust to the forefront since input from the senses isn’t available to cover it up.

MRI Scans Conclude Visual Cortex Activity Creates Hallucinations During REST

Another study conducted in 2000 used magnetic resonance imaging scans (MRIs) to examine what occurred in the brain during sensory deprivation experiences like what happens during the use of chamber REST or flotation tanks.

The MRI scans revealed there was increased activity in the brain’s visual cortex within 60 minutes of light deprivation. The activity continued for a 30-minute period after the volunteers were exposed to light again. The experiment demonstrated a substantial increase in visual cortex excitability with a corresponding decrease in light stimulation.

In other words, when your senses are deprived of input, the areas of the brain aligned with processing stimulation from the senses become more active. This in turn produces the hallucinations recorded back in the 1950s during similar experiments. Researchers in the 1950s didn’t have the equipment to scan the brain during the experiments, but the corresponding reports are similar enough to conclude similar episodes of visual cortex stimulation.

So what does this mean for the average person seeking the experience of sense deprivation? First, you’re not crazy if you start to see lights or swirls of color, hear music or have similar experiences during the use of flotation tank or a REST chamber. It’s just your brain “talking to itself” or the electrical activity within your brain picking up speed.

Second, people have reported increased creativity, problem-solving abilities, and other positive effects after periods of use of flotation tanks or REST chambers. The additional natural stimulation to the brain’s visual and auditory cortexes from sense deprivation may trigger deeper creativity and brain power than people can access during a typical day.

mri scans during sensory deprivation therapy

The Benefits of Sensory Deprivation

Sensory deprivation tanks and REST chambers offer many benefits, including the following.

Lessening Anxiety

Using a sensory deprivation pod or tank lowers anxiety. Although at first participants may feel anxious just being inside the tank, if they can stick it out and work through their feelings, they eventually experience release of anxiety and tension. After the sessions, participants report lessened anxiety levels and a calmer demeanor that lasts for hours or days.

Stress Relief

Numerous studies conducted on people using flotation tanks agree they can lower stress hormones, blood pressure, and generally lessen other physical and psychological effects of stress. Researchers at the Medical College of Ohio tested stress hormones and other physiological functions after the use of REST tanks, according to Discover Magazine.

The tests revealed plasma and urinary cortisol as well as levels of plasma ACTH, hormones associated with stress, were significantly lower after the use of REST pods or tanks. The study’s authors concluded that REST significantly and positively benefited the pituitary-adrenal cortex and offered positive stress relief benefits.

Reduced Pain

Similar studies conducted with volunteers experiencing chronic pain or rheumatoid arthritis also found that REST reduced pain significantly. Volunteers had less anxiety, as well as improved sleep. This is especially helpful given that pain management typically consists of narcotic or other drugs, and REST may offer non-drug relief for pain.

Easing of Insomnia

Insomnia may be caused by both physiological conditions, such as chronic pain, or psychological conditions, such as anxiety. Researchers found insomnia caused by either issue was markedly improved after REST treatments. Thirty-six participants enjoyed 45-minute REST sessions over a two-week period. The study’s participants were given a special machine to take home to assess their sleeping patterns. The resulting improvements in sleep, mood and anxiety levels were noticeable after just two weeks of using REST sessions.

Increased Creativity

REST enhances creativity in many surprising ways. A test conducted at a university compared the differences between six faculty members sitting quietly in their offices for 30 minutes and the same faculty members using a sensory pod or REST tank of warm saline water, darkness, and silence. The subjects dictated their lesson plans into a tape recorder after each session. Ideas generated after the REST session were more creative than those dictated after quiet office time. Additionally, after using the REST tank, participants reported:

  • Enhanced moods
  • Less anxiety
  • Reduced levels of depression, tension, fatigue and confusion

Musicians, composers, writers, and visual artists have used REST tanks to enhance their creative abilities and inspire new thoughts and ideas.

REST offers few side effects and many benefits. Many of the problems it relieves are those modern medicine and science offers few answers for, such as chronic fatigue and pain, insomnia, anxiety and stress. It is a drug-free way to manage these conditions and offers many people marked improvement.

benefits of sensory deprivation therapy

Personal Sensory Deprivation Therapy Experiences: What Is REST Like?

If you’re intrigued by both the reports and the research surrounding sensory deprivation therapy but aren’t sure whether it’s right for you, reading the reports from actual REST participants may be helpful.

Sensory deprivation therapy is now offered at centers in many cities that allow you to pay as you go. You can purchase one session or a group of sessions. There are fully closed REST tanks and those with open tops to help people with claustrophobia issues.

A reporter for the “Today” show visited a Brooklyn “float center” that offers sessions in spacious sensory deprivation pods. She reported the tank was filled with only about 10 inches of water yet saturated with 1,000 pounds of Epsom salt to make you feel buoyant. After stepping into the tank and momentarily resisting the water, as if she had to work to float, she found she could just stretch out, float and enjoy the experience.

At first, thoughts rose her consciousness but eventually she found she had either zoned out or fallen asleep. When the session was over, she reported feeling calm and slightly spacey, but it was a positive experience.

A journalist for Slate magazine reported a similar experience testing out the flotation experience. He experienced similar thoughts, with 15 initial minutes of almost nonstop chatter as his brain seemed to expel every item on his to-do list and all the worries of the day. After the first 15 minutes, however, his mind transitioned into an almost Zen-like state of calm and clarity that he felt was refreshing and appealing. Emerging from the flotation center, the reporter felt colors were more saturated and sounds improved. It was a new experience for him.

One thing to note. Although both reporters experienced the first 15 minutes of brain chatter, the Slate reported said that upon additional floating sensory deprivation sessions, the initial chatter period grew shorter and shorter. His brain seemed to find it easier to slide into the deeply meditative state he found within the sensory deprivation flotation tank.

Are Sensory Deprivation Flotation Tanks or Sensory Deprivation Chambers in Your Future?

Although the product of Cold War-era research on prisoners experiencing sensory deprivation, the current use of sensory deprivation tanks and chambers points the way to their use in peacetime as a drug-free way to offer relief from stress, anxiety, headaches, insomnia and chronic pain.

Researchers still hope for the day when they can use waterproof brain scanners and similar equipment to truly peer into the mind while people experience sensory deprivation. But until such inventions are made, the curious must rely upon the experiences of those like the reporters and many others who have voluntarily enjoyed flotation pods and chambers.

You can recreate some of the REST chamber experience in your home using sound panels and other soundproofing techniques to create a lowered sensory experience. For the utmost in sensory deprivation, a session in a flotation pod or tank may be just what you’re looking for to jumpstart your creativity or lower your anxiety thermostat a notch. It’s worth trying.

For more information about soundproofing and its uses such in sensory deprivation chambers and more, visit Soundproof Cow. It’s clear adding quiet time to your day is a good thing. Whether you need to block sound from noisy neighbors or you need soundproofing for a recording studio, Soundproof Cow is the go-to place for creative inspiration, information and resources.


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