Float tanks eased anxiety in short studies, so ask how the water is cleaned

Key takeaways

• In a 2018 study of 50 adults with anxiety disorders, one hour of floating lowered anxiety in every participant, but the study had no comparison group.
• A 2026 review of eight studies with 401 people with chronic pain found less pain in most, though in one trial a placebo-style comparison group improved too, with no difference at six months.
• No single U.S. rule governs float water: CDC’s voluntary model code calls for UV or ozone treatment, while Florida’s 2018 conditions required a chlorine-type disinfectant and ended hydrogen peroxide use.
• Skip floating if you have open wounds or rashes, a contagious illness, seizures that aren’t controlled, or alcohol or drugs in your system.
• First-timers can leave a light on or the door open, and in one study floating with the lights on lowered anxiety about as much as floating in the dark.

In a research building in Tulsa, Oklahoma, a round pool sits on 48 rubber springs. The springs keep vibrations from the building from reaching the person floating inside¹.

The pool holds 11 inches of water mixed with about 1,800 pounds of Epsom salt, kept at 95°F¹. The room is dark, soundproof and held near skin temperature¹.

In a study published in 2018, researchers at the Laureate Institute for Brain Research put 50 adults with anxiety disorders into that pool for an hour. Afterward, anxiety scores had dropped in every one of them¹.

There’s a twist. Before their float, 15 people didn’t show up and 15 more rescheduled, which the researchers blamed on worry about floating¹.

That mix, strong short-term relief and real hesitation, runs through float research. The science is small but serious. Below, we cover what it shows and how to choose a clean, safe place to try it.

Floating began as a 1950s brain experiment

In the 1950s, two scientists at the National Institute of Mental Health, John Lilly and Jay Shurley, wanted to know what the brain does with almost no outside input¹.

Sources differ on who built the first tank. A 2014 Pacific Standard article credits Lilly with a tank in 1954³. The Laureate team writes that Shurley built the first fully immersive tank in 1957 at the Oklahoma City Veterans Administration hospital, using a helmet and breathing tubes¹. In the 1970s, Glenn Perry, working with Lilly, developed the lie-back, helmet-free tank still used today¹.

Researchers first called this “sensory deprivation,” a phrase with a harsh ring. Researcher Peter Suedfeld gave the practice a gentler name: REST, for Restricted Environmental Stimulation Technique³. Today’s researchers often say “Reduced Environmental Stimulation Therapy”¹.

Research went quiet for years before floating returned as a consumer trend. By 2018, hundreds of float centers had opened across North America and Europe, typically offering 45- to 90-minute sessions for about $40 to $100 each¹.

Two academic groups did much of the modern work. Karlstad University in Sweden ran a float lab from the late 1990s until 2018⁴. The Laureate Institute in Tulsa built its own float clinic¹.

In the tank, your body gets very little to react to

Float water is so salty that you bob on the surface without effort. Health officials describe it as a saturated Epsom salt (magnesium sulfate) solution roughly a quarter denser than plain water, kept at about 92°F to 96°F⁵. That’s close to the temperature of your skin.

Most commercial centers use enclosed pods or tanks, while the Tulsa research pool sits open in a dark room¹.

Floating does measurable things to the body. In a second 2018 study from the Laureate team, 31 people with high anxiety sensitivity floated for 90 minutes on one day and watched a calm nature film on another².

During the float, diastolic blood pressure, the bottom number, fell about 13 points on average. It fell in every participant². During the film, it barely moved².

People also became more aware of their heartbeat and breathing while floating². On average those sensations felt more pleasant, though some people felt worried early on². One woman in the larger 2018 study had a panic attack that began as her float started and built for about 20 minutes. She stayed in the pool and had fully recovered by the end of the hour¹.

Side effects were mild. The most common were itchy skin and a dry mouth¹. One person left early because the salt stung small cuts she hadn’t noticed¹.

Anxiety studies show big drops after one float

The 50-person Tulsa study included people with generalized anxiety disorder, PTSD, social anxiety and panic disorder. Most were also depressed, and 20 were on stable doses of antidepressants¹.

After one hour, anxiety dropped by a very large amount, and post-float scores came close to the pre-float scores of a group of people without anxiety¹. People also reported less stress, muscle tension and pain, and more serenity and energy¹.

The weakness: there was no comparison group. Everyone floated, everyone knew it, and they rated their own feelings¹. The authors noted that expectation and novelty could explain part of the effect¹.

The follow-up study added a comparison, a nature film, and floating came out ahead on relaxation, serenity and muscle tension². But the film group sat upright in a chair, which the authors said likely exaggerated the gap².

The Laureate team then ran a randomized safety trial, assigning people by chance¹⁴. Out of 1,715 people screened, 75 anxious or depressed adults got six weekly floats, floats on a flexible schedule, or six sessions in a zero-gravity reclining chair¹⁴. People stuck with floating well, attending 85% to 89% of sessions, and no serious problems were linked to any option¹⁴. The trial was built to test safety, not whether floating works better than the chair¹⁴.

That chair matters. In a 2020 study of 23 people recovering from anorexia, the reclining chair matched floating on several measures, including anxiety, stress and relaxation¹⁵. The pool still stood out on a few others, such as body image and blood pressure¹⁵. So part of the benefit may come from lying still in a quiet space rather than from the water itself, a question the authors said future trials need to settle¹⁵.

Swedish trials tested stress and chronic pain

At Karlstad University, the focus was stress and muscle pain⁴.

In a 2001 trial, 37 adults with chronic neck and back muscle pain were randomly assigned to nine floats over three weeks or to a control group¹¹. Floaters’ worst pain dropped, they reported less anxiety and depression, and they fell asleep more easily¹¹. Milder everyday pain didn’t change¹¹.

A 2014 pilot trial enrolled 65 healthy workers from three Swedish retail companies¹⁰. Those randomly assigned to float had 12 sessions of 45 minutes over about seven weeks, while the others waited their turn¹⁰. Floaters reported less stress, anxiety and depression, more optimism and better sleep¹⁰. Oddly, both groups reported less energy by the end, and the authors couldn’t explain why¹⁰.

In a 2016 pilot trial of people with generalized anxiety disorder, 37% of floaters fell below the cutoff for the condition after treatment, compared with 14% of those on a wait list¹³. Gains in worry and sleep held at six months, but improvements in depression faded¹³.

The broadest look at pain came in 2026. A scoping review in the Journal of Pain Research pulled together eight studies with 401 people, mostly adults between about 30 and 50 with neck, back or muscle pain¹².

Most studies found less pain¹². But in a 2021 trial that compared floating with a modified, placebo-style session, both groups improved in the short term, and there was no meaningful difference at six months¹². No study reported a side effect¹². The review’s authors reported no outside funding¹².

An evidence map for float tank claims

Float research shares a problem with much relaxation research. You can’t hide a float from the person floating, so true blinding is impossible. Many studies compared floating with a wait list or nothing, relied on self-reported feelings, and rarely followed people for long^1101213.

Much of the work also comes from two research groups, so independent replication is thin. The Swedish lab listed the Swedish Flotation Association as a partner⁴.

In Tulsa, one study received money from the Epsom Salt Council, though the authors said funders had no role in the research². Other Tulsa studies were paid for by a private foundation and the National Institutes of Health¹¹⁴¹⁵. Apply the same scrutiny you would to a drug company’s study.

This table uses four levels: strong evidence, promising but early, not enough evidence, and evidence says no (or unsafe).

Claim	Evidence level	What the research shows
One float lowers anxiety and stress for a few hours	Promising but early	Large drops in open-label studies; floating beat a nature film for relaxation12
A series of floats eases generalized anxiety	Promising but early	One small pilot trial: 37% vs 14% below the symptom cutoff13
Floating eases chronic muscle-tension pain	Promising but early	Most of eight small studies found relief; in one trial a placebo-style group did as well at six months1112
Floating improves sleep	Promising but early	Better sleep in some Swedish trials; mixed results across studies1012
Floating lowers blood pressure	Promising but early	Drops during sessions; no long-term blood pressure trials212
The water does better than a quiet reclining chair	Not enough evidence	A reclining chair gave similar effects in one small study15
Floating raises magnesium levels through the skin	Not enough evidence	None of the studies we reviewed measured it
Floating replaces therapy or medication for anxiety	Not enough evidence	Studies added floating to people’s usual care; none tested it as a substitute112

The salt water still needs cleaning, and the rules disagree

Float water is warm, shared by many bodies, and filtered only between sessions, not during them⁸. That makes cleaning important.

The catch is that all that salt changes the chemistry. Western Australia’s health department notes that high salt can make chlorine readings hard to get⁸. Regulators and the float industry have reached different answers about what to use instead:

• CDC’s model aquatic health code. In 2023, CDC’s model pool code added rules for floatation tanks⁵. It calls for UV light or ozone as the main disinfectant, at least three full turnovers of the water between users, USP-grade Epsom salt, and draining the tank after vomit or diarrhea⁵. It doesn’t mention hydrogen peroxide⁵. The code is guidance, not federal law; it becomes law only where a state, local, territorial or tribal government adopts it⁶. (CDC has since posted a 2024 edition⁶.)
• Florida. In 2018, Florida’s health department treated float tanks as special-purpose public pools. Its variance conditions required a halogen disinfectant, the family that includes chlorine and bromine, at least five turnovers between users, and an end to hydrogen peroxide use⁷. Check whether those 2018 conditions still apply.
• Western Australia. Its 2015 guidelines allow only chlorine or bromine as the main disinfectant, ban hydrogen peroxide, and advise against ozone, which can collect as a gas in the tank⁸. They require testing for Pseudomonas aeruginosa, a germ that thrives in warm water⁸.
• The float industry. The Floatation Tank Association’s 2017 standard allows UV light alone or with hydrogen peroxide or ozone, and discourages chlorine and bromine⁹. It also calls for routine Pseudomonas testing⁹.

The Tulsa research pool used UV lights, hydrogen peroxide, fine filtration and at least four turnovers between floaters¹.

You can’t test the water yourself. You can ask good questions.

Clear answers and recent records are good signs. Vague answers are a reason to look elsewhere.

Who should skip a float, and who should ask first

The float industry’s own standard says people should not float with large open wounds or rashes, contagious skin or respiratory illness, epilepsy that isn’t under medical control, or alcohol or drugs in their system⁹. It also advises against floating soon after shaving or waxing⁹.

Research teams screened more strictly. The Tulsa studies excluded people with bipolar disorder, schizophrenia, active suicidal thoughts, substance use disorders, and neurological conditions such as epilepsy, stroke and dementia². That means there’s little or no safety data for those groups.

Talk with a clinician before you float if:

• You faint easily or have low blood pressure. Blood pressure drops during a float². A 2020 study that watched closely for dizziness on standing, in people recovering from anorexia, found no fainting or falls, but it was small¹⁵.
• You have a serious mental health condition. Floating was added to people’s usual care in the studies, not used in place of it¹¹². Don’t stop medicine or therapy to try it.
• You’re pregnant. None of the float studies we reviewed included pregnant women, so ask your prenatal provider.
• You’re claustrophobic. Enclosed pods may heighten anxiety and claustrophobia, the Laureate team noted¹. An open pool or a float room may be easier.

Your first float, step by step

This routine draws on the research protocols and safety standards above.

1. Book a session that fits your nerves. Commercial floats usually run 45 to 90 minutes¹. Ask for the shorter option the first time.
2. Skip shaving and waxing that day. Cover small cuts with petroleum jelly, as the industry standard suggests⁹.
3. Shower before you get in. Both health rules and the industry standard call for it⁸⁹.
4. Use the comfort tools. Earplugs and a neck float are common options⁹. Ask how to find the door and light switch in the dark⁹.
5. Keep salt out of your eyes. Don’t put your face under water⁸. Ask how to rinse your eyes if salt gets in⁹.
6. Leave a light on if you want. In the 2018 Tulsa study, anxiety dropped about as much with the light on as with it off¹.
7. Expect a restless start. In one study, a woman who panicked early stayed in and felt fine by the end¹. You can still sit up or get out at any time.
8. Get up slowly. Your blood pressure may be lower than when you got in². Sit for a moment before you stand.
9. Shower again. Rinse off all the salt⁹.

When to get help. If you feel faint, have chest pain or a seizure, or feel panic you can’t calm, use the call button if the tank has one, or get out, and call 911 if symptoms are severe. If you get a rash or infection afterward, see a clinician and report the facility to your local health department.

Rest is a natural-health value, and floating is one way to get it

Many natural-health traditions treat rest, quiet and paying attention to the body as medicine. Float research lines up with that idea.

What seems to help is simple: warmth, stillness, darkness and silence¹. The reclining-chair results hint that you may get part of the benefit from any deep, quiet rest¹⁵. That’s encouraging if a float center is too far away or too costly.

So consider floating a tool, not a cure. If an hour in the tank leaves you calmer, enjoy that. If you live with anxiety, depression or chronic pain, use it alongside care with stronger evidence, and tell your clinician.

Questions readers ask

The bottom line

Floating in warm, salty water in a dark, quiet space seems to calm anxiety and stress for at least a few hours, and it may ease muscle-tension pain for a while. The studies are small, mostly unblinded and concentrated in two research groups, so lasting benefits are still unproven.

If you want to try it, choose a center that can tell you how its water is disinfected and tested, start with a shorter session, and leave the light on if that helps. Skip it with open wounds, contagious illness, uncontrolled seizures or alcohol in your system, and talk with a clinician first if you have low blood pressure, a serious mental health condition or are pregnant.

Keep exploring: contrast therapy, infrared sauna benefits and wellness device contraindications.

Related reading

• Contrast therapy eases soreness a little, and its bigger effect is on your heart
• The famous sauna longevity study used Finnish saunas, not infrared cabins
• What meditation groups can do, and what they can stir up
• Most health products aren’t scams, but many just haven’t been proven
• Six questions to ask before you buy anything for your health

Sources

1. Feinstein JS, Khalsa SS, Yeh H-w, Wohlrab C, Simmons WK, Stein MB, Paulus MP. “Examining the Short-Term Anxiolytic and Antidepressant Effect of Floatation-REST.” PLoS ONE, 2018. journals.plos.org
2. Feinstein JS, Khalsa SS, Yeh H, et al. “The Elicitation of Relaxation and Interoceptive Awareness Using Floatation Therapy in Individuals With High Anxiety Sensitivity.” Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, 2018. globalwellnessinstitute.org
3. Winkler J. “What Are the Benefits of Locking Yourself in a Tank and Floating in Room-Temperature Saltwater?” Pacific Standard, 2014. psmag.com
4. Karlstad University. “Research on Relaxation in a Flotation Tank.” Karlstad University. kau.se
5. National Association of County and City Health Officials. “Safely Managing Floatation Tanks: A Quick Guide for Health Departments and Operators.” NACCHO, 2023 (CDC Stacks). stacks.cdc.gov
6. U.S. Centers for Disease Control and Prevention. “Model Aquatic Health Code.” CDC. cdc.gov
7. Florida Department of Health Advisory Board. “Summary of Epsom Salt Float Tank Code Citations.” Florida Department of Health, 2018.
8. Department of Health, Western Australia. “Guidelines for Floatation Tank Installation, Operation, Monitoring and Risk Management.” Government of Western Australia, 2015. smhs.health.wa.gov.au
9. Floatation Tank Association. “North American Float Tank Standard, Version 2.” 2017 (hosted by Montana Department of Public Health and Human Services). dphhs.mt.gov
10. Kjellgren A, Westman J. “Beneficial Effects of Treatment With Sensory Isolation in Flotation-Tank as a Preventive Health-Care Intervention – A Randomized Controlled Pilot Trial.” BMC Complementary and Alternative Medicine, 2014. link.springer.com
11. Kjellgren A, et al. “Effects of Flotation-REST on Muscle Tension Pain.” Pain Research & Management, 2001. pubmed.ncbi.nlm.nih.gov
12. Stuart SJ, Achury LK, Kline M, Bair MJ. “A Scoping Review of Flotation-REST (Restricted Environmental Stimulation Therapy) for Chronic Pain and Associated Comorbidities.” Journal of Pain Research, 2026. dovepress.com
13. Jonsson K, Kjellgren A. Randomized controlled pilot trial of flotation-REST for generalized anxiety disorder. BMC Complementary and Alternative Medicine, 2016. link.springer.com
14. Garland M, Wilson R, Thompson W, Stein M, Paulus M, Feinstein J, Khalsa S. “Data From: A Randomized Controlled Safety and Feasibility Trial of Floatation-REST in Anxious and Depressed Individuals.” Dryad, 2024. datadryad.org
15. Khalsa SS, Moseman SE, Yeh H-W, et al. “Reduced Environmental Stimulation in Anorexia Nervosa: An Early-Phase Clinical Trial.” Frontiers in Psychology, 2020. frontiersin.org