Zero Gravity Float, Cork
Float Science: Research on Floatation Therapy
What the research says about floatation therapy: 24 peer-reviewed studies on anxiety, pain, sleep and recovery, summarised in plain English.
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Floatation therapy has been studied for decades, from early work on stress and muscle pain to recent trials in anxiety, depression, chronic pain, sleep and exercise recovery. Below are 24 peer-reviewed studies grouped by topic, each with a plain-English summary and a link to the original paper.
How to read this research
- Most of these studies are small, and several had no comparison group.
- Many come from the same few research teams.
- Treat the findings as promising rather than proven. One of the better-designed trials, on chronic pain, found no long-term benefit, and it is included here.
- Each study has a label showing its design, from randomised trials, which are the strongest, to small pilots. Every summary links to the original paper.
Floating is not a replacement for medical care. If you have a health condition, please speak to your doctor first. We update this page as new research is published.
- Overviews and reviews (2)
- Anxiety and depression (5)
- Stress, relaxation and the body (5)
- Pain and tension headache (6)
- Sleep, sport and recovery (4)
- Eating disorders and body image (2)
Overviews and reviews
Two overviews that pull many studies together. A good place to start if you want the big picture before the individual trials.
Floatation Therapy for Specific Health Concerns
In short: A review for healthcare providers: floating looks helpful for muscle pain and mental health, but most studies are small and dated.
Writing for healthcare professionals, the authors searched multiple databases, narrowed 199 articles to the most relevant, and reviewed the findings. They reported benefits for muscular pain, depression, anxiety, stress and sleep problems, with long-term benefits that appear variable. They also cover who should avoid floating, and call for larger studies.
Witte et al. (2021). Natural Medicine Journal. Published as: “Floatation Therapy for Specific Health Concerns: A review of the research on this increasingly popular intervention”
Floatation restricted environmental stimulation therapy (REST) as a stress-management tool: A meta-analysis
In short: A meta-analysis of 27 studies concluded that floating can be a useful stress-management tool.
The researchers pooled 27 studies covering the effects of floating on physiology, well-being and performance. They concluded that, despite limitations in the original studies, floating can be a useful stress-management tool in addition to or instead of other tools. Most of the studies were of healthy volunteers and were published between 1983 and 2002.
van Dierendonck & te Nijenhuis (2005). Psychology & Health. Published as: “Flotation restricted environmental stimulation therapy (REST) as a stress-management tool: A meta-analysis”
Anxiety and depression
Most of the recent work is here, much of it from the Laureate Institute for Brain Research in Tulsa, Oklahoma. Studies range from single-session trials to a randomised comparison of six sessions.
A randomised controlled safety and feasibility trial of floatation-REST in anxious and depressed individuals
In short: Six sessions of floating were practical, well tolerated and safe for people with anxiety and depression.
75 adults with anxiety and depression were randomly assigned to six weekly one-hour floats, six floats with flexible length and frequency, or an active comparison (a zero-gravity chair). Attendance was 85% and 89% in the two float groups and 74% in the chair group. There were no serious adverse events, and positive experiences were reported more often than negative ones. This trial tested safety and feasibility, so it cannot show that floating treats anxiety or depression. The authors call for larger trials.
Garland et al. (2024). PLOS ONE. Published as: “A randomized controlled safety and feasibility trial of floatation-REST in anxious and depressed individuals”
Reduced Environmental Stimulation Therapy (REST) in anxiety and depression: An experience sampling study
In short: The calming effects of floating lasted around 48 hours in people with anxiety and depression.
In the same 75-person trial, participants answered short smartphone surveys before and after each session, and again 4, 8, 24 and 48 hours later. Anxiety and depression scores fell and feelings of serenity rose, with effects lasting up to 48 hours. People also started later sessions with lower baseline anxiety, which hints that repeated sessions may add up. The authors describe these as initial findings.
Garland et al. (2023). Journal of Mood and Anxiety Disorders.
The Elicitation of Relaxation and Interoceptive Awareness Using Floatation Therapy in Individuals With High Anxiety Sensitivity
In short: A single 90-minute float lowered anxiety and blood pressure in people with high anxiety sensitivity.
31 people with high anxiety sensitivity each had a 90-minute float and a comparison session, in random order. Compared with the comparison session, floating reduced state anxiety and muscle tension and increased relaxation and serenity, and diastolic blood pressure fell by an average of about 12.8 mm Hg. Participants also became more aware of their heartbeat and breathing.
Main findings
Systolic blood pressure fell by approximately 5 mm Hg, and diastolic blood pressure showed a more pronounced reduction of approximately 13 mm Hg, often within the first 5 minutes of the float. There was a substantial reduction in state anxiety and muscle tension, substantial increases in serenity and relaxation, and significantly enhanced awareness and attention for cardiorespiratory sensations.
Highlights
The float environment elicited a relaxation response that was evident both physiologically (reduced blood pressure) and psychologically (reduced state anxiety and muscle tension, increased relaxation and serenity). The paradoxical nature of the anxiolytic effect in this sample is discussed in relation to Wolpe's theory of reciprocal inhibition and the regulation of distress via sustained attention to present-moment sensations such as the breath. The authors suggest the reduction in anxiety is likely a by-product of an environment that minimises exposure to most external triggers of stress, giving a chronically anxious nervous system a rare respite. The reduction in muscle tension, especially in the upper and lower back, was one of the more prominent effects.
Feinstein et al. (2018). Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.
Examining the short-term anxiolytic and antidepressant effect of Floatation-REST
In short: A single one-hour float sharply reduced anxiety in 50 people with anxiety and stress-related disorders.
Participants had conditions including post-traumatic stress, generalised anxiety, panic, agoraphobia and social anxiety, and most (46) also had depression. After one one-hour float they reported large reductions in state anxiety, and lower stress, muscle tension, pain, depression and negative mood. There was no comparison group, so the authors called for replication in larger controlled trials.
Main findings
Nearly 75% of the sample, and 82% of the severely anxious subgroup, reported achieving more relaxation with Floatation-REST than with any other treatment or technique they had tried in the past.
Highlights
The top 10 rated effects on the side-effect checklist were all positive. The top three were a feeling of total serenity and peacefulness, total relaxation of the body without any muscle tension, and feeling completely refreshed. The reduction in state anxiety was evident across all 50 participants (a large effect, d = 2.15). Despite a large baseline difference, the anxious group's average post-float anxiety was slightly lower than the pre-float anxiety of the non-anxious reference sample.
Feinstein et al. (2018). PLOS ONE.
Promising effects of treatment with floatation-REST (restricted environmental stimulation technique) as an intervention for generalised anxiety disorder (GAD): a randomised controlled pilot trial
In short: A small randomised pilot trial found floating reduced symptoms of generalised anxiety disorder.
People with generalised anxiety disorder were assigned to a floating programme or a control group, and symptoms changed significantly more in the float group over time. The authors concluded that floating may have potential as a complementary treatment alongside existing treatment for the disorder, and called for more studies.
Jonsson & Kjellgren (2016). BMC Complementary and Alternative Medicine. Published as: “Promising effects of treatment with flotation-REST (restricted environmental stimulation technique) as an intervention for generalized anxiety disorder (GAD): a randomized controlled pilot trial”
Stress, relaxation and the body
Studies of what happens in the body and brain during and after a float, including blood pressure, heart rate variability, brain connectivity and stress hormones, plus early work on stress and burnout.
Exploring the acute cardiovascular effects of Floatation-REST
In short: Floating lowered blood pressure and breathing rate compared with watching a relaxing nature film.
37 clinically anxious adults and 20 non-anxious adults each did a 90-minute float and a 90-minute nature-film session, in random order. Compared with the film, floating produced significant drops in systolic and diastolic blood pressure and in breathing rate, along with changes in several heart rate variability measures. Blood pressure was the only measure linked to the float-related drop in anxiety, and the changes were similar in anxious and non-anxious people.
Flux et al. (2022). Frontiers in Neuroscience.
Taking the body off the mind: Decreased functional connectivity between somatomotor and default-mode networks following Floatation-REST
In short: Floating changed how brain networks linked to the sense of self communicate with each other.
Healthy adults aged 18 to 55 had brain scans before and after 90 minutes of floating, or 90 minutes resting in a zero-gravity chair. After floating, connectivity fell within and between parts of the default-mode network (linked to mind-wandering and self-reflection) and the somatomotor cortex, which maps body sensation. The chair condition showed a similar pattern, so the effect may reflect reduced stimulation more broadly rather than floating alone.
Al Zoubi et al. (2021). Human Brain Mapping.
Preventing Sick-leave for Sufferers of High Stress-load and Burnout Syndrome: A Pilot Study Combining Psychotherapy and the Floatation tank
In short: A small pilot combined floating with psychotherapy for people with burnout, and all six participants stayed at work.
Six adults (four women and two men aged 33 to 57) took part in a 10-week programme combining relaxation in a float tank with psychotherapy sessions, with the aim of preventing sick leave in people with a high stress load and burnout syndrome. Afterwards they showed lower depression and anxiety, a more positive outlook, fewer painful areas and less severe worst-case pain, and none needed sick leave. The authors called the approach promising and recommended a randomised trial. With only six participants it can only be read as an early pilot.
Kjellgren et al. (2011). International Journal of Psychology and Psychological Therapy. Published as: “Preventing Sick-leave for Sufferers of High Stress-load and Burnout Syndrome: A Pilot Study Combining Psychotherapy and the Flotation tank”
Eliciting the Relaxation Response With the Help of Floatation-REST (Restricted Environmental Stimulation Technique) in Patients With Stress-Related Ailments
In short: Looked at whether floating can trigger the body's relaxation response in people with stress-related ailments.
Patients with stress-related ailments took part in a floating programme, and the researchers examined whether floating elicits the relaxation response, a state of reduced physiological arousal. See the full paper for the design and results.
Bood et al. (2006). International Journal of Stress Management. Published as: “Eliciting the Relaxation Response With the Help of Flotation-REST (Restricted Environmental Stimulation Technique) in Patients With Stress-Related Ailments”
Restricting environmental stimulation influences levels and variability of plasma cortisol
In short: Floating changed the level and variability of the stress hormone cortisol in healthy volunteers.
27 healthy people were studied. The authors concluded that restricting environmental stimulation affects both the level and the variability of plasma cortisol, possibly by altering the feedback control of the hormone. The levels and their variability were tracked across repeated sessions. This is a laboratory study in healthy volunteers, so it says little about treating any condition.
(1991). Journal of Applied Physiology.
Pain and tension headache
This is where the evidence is most mixed. Swedish studies from the 2000s reported improvements in muscle-tension pain. A 2021 randomised trial in Germany found no lasting benefit over placebo for chronic pain. We have included both.
Floatation Restricted Environmental Stimulation Therapy for Chronic Pain
In short: Five float sessions did not ease chronic pain over the long term in a placebo-controlled trial.
99 adults with chronic pain were randomly assigned to five float sessions, a placebo condition in the same tank (designed to control for effortless floating and sensory restriction) or a wait-list. Sessions lasted 60 to 90 minutes and were four days apart. There was no difference between groups in the main outcome, pain intensity a week after the last session, or at the 12 and 24 week follow-ups. In the short term the float group did report more relaxation and less anxiety and pain, but the placebo group showed similar changes, so those short-term effects cannot be put down to floating alone. We include it because it is one of the more rigorous trials in the field.
Loose et al. (2021). JAMA Network Open. Published as: “Flotation Restricted Environmental Stimulation Therapy for Chronic Pain: A Randomized Clinical Trial”
Treating stress-related pain with the floatation restricted environmental stimulation technique: Are there differences between women and men?
In short: Women and men with stress-related muscle pain both showed improvements after 12 float sessions.
A secondary analysis of 88 patients (69 women, 19 men) with chronic stress-related muscle tension pain, who each had 12 float sessions over seven weeks, drawn from three earlier studies. Women were more depressed than men before treatment but not after. Both sexes improved their ability to tolerate experimentally induced pain, although men showed greater endurance both before and after.
Bood et al. (2009). Pain Research & Management. Published as: “Treating stress-related pain with the flotation restricted environmental stimulation technique: Are there differences between women and men?”
Effects of floatation REST (Restricted Environmental Stimulation Technique) on stress-related muscle pain: are 33 floatation sessions more effective than 12 sessions?
In short: For muscle-tension pain, 12 float sessions appeared to be enough, and 33 sessions added nothing more.
37 patients (29 women, 8 men) with stress-related muscle tension pain were randomly assigned to 12 or 33 float sessions. Pain improved considerably after 12 sessions, with no further improvement after 33. Blood pressure was the exception: diastolic pressure was lower only after 33 sessions. The same pattern held for stress, anxiety, depression, optimism and sleep quality. The authors suggested that other complementary treatments may help patients progress beyond the first 12 sessions.
Bood et al. (2007). Social Behavior and Personality. Published as: “Effects of flotation REST (Restricted Environmental Stimulation Technique) on stress related muscle pain: are 33 flotation sessions more effective than 12 sessions?”
Effects of floatation REST (restricted environmental stimulation technique) on stress-related muscle pain: What makes the difference in therapy: attention-placebo or the relaxation response?
In short: Asked whether pain relief from floating comes from the relaxation response or from attention and expectation.
32 patients with stress-related muscular pain took part in a study that set out to separate the effect of attention and expectation (the attention-placebo effect) from the effect of the relaxation response produced by floating. The patients floated for six weeks, 16 of them also had a diagnosis of burnout depression, and the participants had lower blood pressure afterwards. See the full paper for the pain results and the comparison with attention-placebo.
Bood et al. (2005). Pain Research & Management. Published as: “Effects of flotation-restricted environmental stimulation technique on stress-related muscle pain: what makes the difference in therapy--attention-placebo or the relaxation response?”
Effects of floatation-REST on muscle tension pain
In short: Nine float sessions over three weeks reduced the most severe pain in people with muscle-tension pain.
37 participants were randomly assigned to a control group (17) or a float group (20), who had nine opportunities to float over three weeks. The most severe perceived pain intensity fell significantly in the float group, while lower-intensity pain was unchanged. They also reported more optimism, less anxiety and depression, and fell asleep more easily at night.
Kjellgren et al. (2001). Pain Research & Management. Published as: “Effects of flotation-REST on muscle tension pain”
Progressive muscle relaxation and restricted environmental stimulation therapy for chronic tension headache: a pilot study
In short: An early pilot combined progressive muscle relaxation training with floating for chronic tension headache.
The researchers reasoned that floating, which is reported to encourage a relaxed but focused state, might add to the benefit of progressive muscle relaxation training in people with chronic tension headache. It was an early pilot study from 1991, so it is best read as a starting point rather than as evidence of benefit.
Wallbaum et al. (1991). International Journal of Psychosomatics.
Sleep, sport and recovery
Studies of floating after exercise and of its effect on sleep, in elite athletes, team-sport players and trained lifters.
Acute Floatation-REST Improves Perceived Recovery Following a High-Intensity Resistance Exercise Stress in Trained Men
In short: After a hard leg workout, a one-hour float improved how recovered trained men felt.
Trained men completed a demanding session of six sets of ten back squats, then either floated for an hour or had a passive recovery period with sensory stimulation, in separate blocks. Floating improved perceived recovery, meaning how recovered the men felt.
Caldwell et al. (2022). Medicine & Science in Sports & Exercise. Published as: “Acute Floatation-REST Improves Perceived Recovery After a High-Intensity Resistance Exercise Stress in Trained Men”
Does floatation-REST (restricted environmental stimulation technique) have an effect on sleep?
In short: A systematic review found beneficial effects on sleep in all nine included studies, though the quality of sleep measures was low.
The review searched PubMed, Google Scholar, Web of Science and PsycINFO and included nine studies that measured sleep. All reported beneficial effects, in clinical and non-clinical groups, and two found the effects lasted 4 to 6 months. The authors rated the quality of the sleep measures as low in most studies, and concluded that floating may be promising for insomnia symptoms but that more controlled studies are needed.
Kjellgren et al. (2020). European Journal of Integrative Medicine. Published as: “Does flotation-rest (restricted environmental stimulation technique) have an effect on sleep?”
Floatation-restricted environmental stimulation therapy improves sleep and performance recovery in athletes
In short: In team-sport athletes, floating after exercise was linked to better sleep and recovery of performance.
19 trained male team-sport athletes completed two trials a week apart: one hour of floating after exercise, or one hour of passive recovery. The study looked at recovery of performance and at sleep, and reported improvements in both after floating. It was a small study of men only.
(2019). Performance Enhancement & Health. Published as: “Flotation-restricted environmental stimulation therapy improves sleep and performance recovery in athletes”
Floatation restricted environmental stimulation therapy and napping on mood state and muscle soreness in elite athletes: A novel recovery strategy?
In short: Elite athletes reported better mood and less muscle soreness after floating.
60 international-level athletes (28 men, 32 women) from nine sports floated after training. Mood improved on 15 of 16 mood measures and perceived muscle soreness fell by an average of 1.6 points out of 10. Combining floating with napping gave further improvement on 5 of the mood measures. Results compare before and after floating.
Main findings
Analysis of pre to post float data showed significant improvements in 15 of the 16 mood-state variables and in perceived muscle soreness. When floating was combined with napping, there was an additional significant improvement in 5 of the 16 mood-state variables. The largest effects were seen in feeling less worn out, less tired, more relaxed, more at ease and more fresh.
Highlights
All athletes volunteered, had not floated before, and represented their country at international level in athletics, basketball, boxing, cycling, football, netball, rowing, rugby or swimming. The study took place in-season over 6 months. Perceived muscle soreness fell significantly (p < 0.01), with a mean reduction of 1.6 out of 10 and a large effect size. The greatest change was in the relaxed mood sub-scale. The findings support earlier research showing improved mood after floating, including a meta-analysis that reported large improvements in psychological wellbeing (Van Dierendonck & Te Nijenhuis, 2005).
Driller & Argus (2016). Performance Enhancement & Health. Published as: “Flotation restricted environmental stimulation therapy and napping on mood state and muscle soreness in elite athletes: A novel recovery strategy?”
Eating disorders and body image
Researchers have tested floating alongside usual care in people with anorexia nervosa. This is early-stage research on a serious condition, and floating is not a treatment for anorexia nervosa. If you or someone close to you is affected, please speak to your GP or an eating disorder service such as Bodywhys.
The impact of floatation therapy on body image and anxiety in anorexia nervosa: a randomised clinical efficacy trial
In short: In hospital inpatients with anorexia nervosa, body dissatisfaction and anxiety fell after floating sessions, and body dissatisfaction was still lower six months later.
68 women and girls in hospital for anorexia nervosa were randomly assigned, two to one, to eight twice-weekly 60-minute floats alongside usual care (45 people) or to usual care alone (23). After individual float sessions the float group reported lower body dissatisfaction and lower anxiety, while the usual-care group showed no change. At the six-month follow-up, body dissatisfaction was lower than at the start for the float group and unchanged for the usual-care group. It was a modest sample at a single hospital, so this is early-stage research, and floating is not a treatment for anorexia nervosa.
Choquette et al. (2023). eClinicalMedicine.
Reduced environmental stimulation in anorexia nervosa: an early phase clinical trial
In short: People with anorexia nervosa tolerated floating and reported less anxiety and body dissatisfaction afterwards.
21 partially weight-restored outpatients completed four 90-minute sessions about a week apart: one in a zero-gravity chair, one in an open pool and two in an enclosed float pool. There was no drop in blood pressure on standing and no adverse events. After sessions participants reported lower anxiety, less negative mood and less body image dissatisfaction. With no control group this was a safety and early-effect study, and the authors called for randomised trials in acutely ill patients.
Khalsa et al. (2020). Frontiers in Psychology. Published as: “Reduced Environmental Stimulation in Anorexia Nervosa: An Early-Phase Clinical Trial”
