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What It’s Like Inside a Sensory Deprivation Tank

What happens when you spend an hour floating in warm water, darkness and silence? At 80, I decided to find out

Catherine Hiller,

AARP

Published September 01, 2026

An illustration shows an older woman floating comfortably on her back in a blue-lit sensory deprivation tank with its lid open.

For some, float tanks lower stress levels and ease joint pain.

Lars Leetaru

When I first heard about float tanks, I was intrigued. Designed for deep relaxation, they work by providing an environment of minimal sensory input. The water is 98.6 degrees, and the room is completely dark. Magnesium sulfate (Epsom salts) in the purified water keeps you buoyant, as if you were afloat in the Dead Sea. You do not touch the bottom or sides of the tub.

I wondered what sensory deprivation would really be like. Would I be driven inward to meet my demons? Would I be spiritually fulfilled? Or would I just be bored?

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A float pool is “one of the few places on earth where the gravity is turned off,” says Justin Feinstein, a clinical neuropsychologist. Founder of the nonprofit Float Research Collective, Feinstein is an advocate for Reduced Environmental Stimulation Therapy, words surely chosen for their lulling abbreviation: REST. Theoretically, float therapy enables people to quiet their minds, quell their anxieties and completely REST.

A 2025 review of 63 Flotation REST studies based on 1,838 participants provides cautious support for the theory.

While Flotation-REST was found to have no significant effect on sleep-related disorders, participants reported positive effects on mental well-being, stress, athletic performance, clinical anxiety and chronic pain. By allowing the body to float effortlessly, the therapy reduces pressure on the spine and joints.

Catherine Hiller smiles on a sandy beach at sunset while standing with her hands on her hips.

Author Catherine Hiller at a sensory-rich Sag Harbor beach on New York's Long Island.

Courtesy Catherine Hiller

The potential for deep relaxation was enough of a draw for me. So I booked a session at a suburban village half an hour from my own. “Goodbye, Facebook; goodbye, email,” I thought. Hello, inner peace!

I’d imagined the float place would be futuristic and high-tech, featuring steel, glass and dials. Instead, the waiting room had wooden tables, a soft couch and a hippie vibe. A chatty girl at the front desk described the procedure. Each room had a shower and a tank. First, I would shower. Then I’d go into the tub. Afterward, I would shower again to get the salts off my skin.

“Once I was in a hurry and didn’t shower afterward,” the girl told me, “and my skin had a white layer of salt on it.”

I followed her to one of the float rooms. This, too, had a natural feel, with plants on the shelves and wood on the side of the tank. The water was a beautiful indigo hue. “Do you want me to change the color?” She pointed a remote control, and the water turned raspberry, then green.

“The blue was nice,” I said. Soon the light would be off, so it didn’t really matter.

The rise of float tanks

The sensory deprivation tank was invented in the 1950s by John C. Lilly. Trained as a physician and neuroscientist, he wanted to study what happened when the brain was deprived of external stimulation. Some researchers believed that conscious mental activity would diminish or become disorganized. Instead, while in the tank, Lilly and his subjects remained mentally active, and many reported a feeling of peace.

Today, isolation tanks are having a moment. According to Feinstein, there are about 500 flotation spas in the United States. A typical session involves floating for an hour in warm water into which 1,000 pounds of Epsom salts have been dissolved, for each individual pool! Some tanks are enclosed. Others are open, shallow pools. I chose the latter — a less claustrophobic option, and easier to enter.

I closed the door behind me and removed all my clothes. I took off my watch and put it in a pocket of my handbag where I could easily find it. Perhaps I would need to leave the tub to see how much more time I had left...before I went stark raving mad!

I took the requisite shower. Then I inserted the balls of wax the spa had provided into my ears for complete soundproofing and to prevent any ear discomfort. Although I didn’t need it, Vaseline was also on offer to protect any cuts or scabs from the salts.

I got into the tub of blue water. I switched off the light. I lowered myself down. I lay on my back. My hair floated around me.

Ahhhhhh. It felt wonderful being in that friendly water. I surrendered myself to darkness and silence.

The only obstacles to total well-being were my breasts, which floated above the water and got a little chilly. From time to time I would warm them with my hands. I don’t think the air was 98.6 degrees as it should have been.

After a few minutes, I happened to move my jaw from side to side, which usually results in a faint creaking sound. Now I felt it as a hammering in my mouth! Astonished, I did it again, and sure enough, it sounded like my mouth was a construction site. From time to time throughout the session, I’d do it again, and always I would get the same bizarre result.

The elimination of external stimuli helps one focus on internal effects. Some people hear their hearts beating, their blood pulsing through their veins, their eyelids meeting. I just heard my jaw.

‘My whole body was smiling’

A hum woke me up, and a dim light came on. It was time to leave my water womb. I felt light, in both senses of the word: glowing and weightless. I took a shower to wash off the salts.

I slowly got dressed. My whole body was smiling.

The next morning, I felt it again, that lightness in my body, that glow from within.

For some reason, I tried my morning coffee without sugar and was surprised at the result. Without the heaping teaspoon of sugar I regularly use, the taste was interesting, nuanced. At lunch, I had my coffee without sugar again. Does this have anything to do with my time in the tank? I don’t know. I do know that I want to go back there. At 80 years old, I am happy to discover new pleasures.

Want to Try Floating?

Here are some tips to get started.

Google or Yelp can help you find a float spa in your area. If there are none close by, perhaps a flotation session can be part of your next vacation.

One-hour float sessions generally cost between $60 and $100, with some places offering lower introductory rates. Some people book weekly sessions, much like scheduling a regular massage.

You are advised not to shave on the day you float (although unwittingly, I did, and my legs didn’t sting).

There's no need to bring a bathing suit or a towel with you.

If you start to panic or feel uncomfortable, you can turn on a light or call an attendant at any time.

AARP essays share a point of view in the author’s voice, drawn from expertise or experience, and do not necessarily reflect the views of AARP.

Catherine Hiller is the author of two children’s books, six novels, a story collection and Just Say Yes: A Marijuana Memoir. She last wrote for AARP The Magazine about memorizing the location of all the countries in the world. Her Substack is The Pleasure Principle: Savoring Life Over 50.

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