Floating (isolation tank)

What it is

The tank is an enclosed cabin or an open pool with shallow water saturated with Epsom salt. Because of the high salt content, the body floats on the surface by itself. The water is heated to skin temperature, and light and sound are switched off or dampened. In the studies, a session usually lasts one hour.

The method originates from research on sensory deprivation and isolation and was later developed further as a relaxation technique. Today there are floating centers in many cities, along with research groups in the USA, Sweden and Germany studying the procedure in anxiety, pain and eating disorders.

How it is supposed to work

The idea is simple: when sight, hearing, temperature, gravity and movement almost disappear as stimuli, the baseline activation of the nervous system decreases. At the same time, attention turns inward. In studies, floaters perceive their heartbeat and breathing much more strongly than people in a comfortable reclining chair.

Precisely this shift in attention is today the most discussed explanation. Researchers describe an altered state of consciousness with a feeling of boundlessness that was linked to the improvement in mood. Biological markers such as stress hormones have been measured, but the results are inconsistent. A mechanism that goes beyond deep relaxation is not established.

What users report

People who float often describe, even after the first session, a feeling of weightlessness, a dissolving sense of time and relaxed muscles. Many report an afterglow, a calm, elevated mood for the rest of the day. One study found that this afterglow depended on how deep the relaxation in the tank was.

Some need several attempts before they can let go. The first minutes with claustrophobia or racing thoughts are not a bad sign. In enclosed cabins, you can leave the lid or door open and control the light yourself.

What the studies show

Jonsson and Kjellgren 2016 — generalized anxiety

50 people with self-reported generalized anxiety disorder, 25 each in the floating and waiting-list groups, 12 sessions. The primary endpoint, anxiety symptoms, improved significantly more with floating. 37 percent of those treated were in full remission afterwards. Sleep problems and emotion regulation also improved. The study was not blinded.

Choquette 2023 — anorexia

68 female inpatients, 45 with floating in addition to standard treatment, 23 with standard treatment only. 8 sessions of 60 minutes each over 4 weeks. The primary endpoint was body dissatisfaction, and it was met. After 6 months, it was lower in the floating group, effect size 0.53. There were no study-related side effects.

Loose 2021 — chronic pain with placebo

99 people with chronic pain disorder at Hannover Medical School, allocated to floating, an indistinguishable placebo in the same tank and a waiting list. 5 sessions of 60 to 90 minutes each. The primary endpoint was pain intensity one week after the last session. It was missed, and there was no difference in the long term either. In the short term, the floating and placebo groups improved equally.

Where the data stop

Most studies compared floating with a waiting list or standard treatment. In that case, it remains open how much of the effect is due to expectation and attention. The only study with a genuine sham treatment found no specific advantage in chronic pain: the improvement also occurred in the placebo tank. This does not speak against the experience, but against the assumption that sensory reduction itself is the active ingredient.

For sleep disorders and smoking cessation, the review found little to no effect. In trained athletes, an hour of floating did not improve heart rate variability, whereas a nap did. The claim that significant amounts of magnesium are absorbed through the skin is considered scientifically unsupported. Advertising claims about blood pressure, detoxification, PTSD or ADHD are not based on controlled studies.

Status, approval and legal

Floating is a wellness service and not covered by statutory health insurance; you pay for it yourself. There is no approval procedure and no state quality control specifically for floating centers. You can recognize reputable providers by visible water hygiene with filtration and disinfection between guests, an introduction before the first session, the option to open the cabin at any time, and the fact that they make no promises of healing.

Safety

Floating is well tolerated. In the randomized studies with patients with anxiety, depression and anorexia, no serious side effects occurred, not even over six sessions. The very salty water stings in the eyes and in fresh cuts or shaving nicks. With pronounced claustrophobia, an open pool or an open lid helps. Anyone who has epilepsy, a cardiovascular disease, an open skin condition or an infection, or who is pregnant, should clarify this with a doctor beforehand. Floating does not replace psychotherapy for anxiety disorders, but can accompany it.

Sources

• Lashgari et al., BMC Complement Med Ther 2025 (systematic review)
• Feinstein et al., PLoS One 2018 (anxiety, single session)
• Jonsson, Kjellgren, BMC Complement Altern Med 2016 (generalized anxiety, RCT)
• Choquette et al., EClinicalMedicine 2023 (anorexia, RCT)
• Loose et al., JAMA Netw Open 2021 (chronic pain, placebo-controlled)
• Garland et al., PLoS One 2024 (safety and feasibility, RCT)
• Stuart et al., J Pain Res 2026 (review, chronic pain)
• Besson et al., BMJ Open Sport Exerc Med 2024 (floating vs. nap)
• Gröber et al., Nutrients 2017 (transdermal magnesium)
• Pantazis, Wittmann, Conscious Cogn 2025 (afterglow after floating)