Floatation REST

1. Introduction

Version followed: the open-pool floatation-REST research protocol of the Laureate Institute for Brain Research, Tulsa (Feinstein, Khalsa and colleagues: the 2018 interoception crossover study and the 2023–24 randomised safety and feasibility trial), with the Karlstad tank programme (Kjellgren; 12 sessions of 45 minutes) as a named variant and Suedfeld and Borrie's REST framework for chamber REST. Chamber REST and week-long darkness stays appear as variants only.

REST stands for Restricted (or Reduced) Environmental Stimulation Technique/Therapy. Peter Suedfeld and Roderick Borrie coined the term to replace "sensory deprivation", which they considered inaccurate [source: Suedfeld, UBC REST page]. It is an environment and technique, not a psychotherapy. There is no published treatment manual for a talking therapy built around it. The trial protocols below describe screening, preparation, the session environment, instructions, scheduling, safety monitoring and debriefing. Anything here about weaving floats into psychotherapy is marked [synthesis].

There are two forms [source: Suedfeld, UBC REST page]:

• Flotation REST: the client lies on their back in a shallow pool of Epsom-salt (magnesium sulphate) solution at roughly skin temperature, in a dark, quiet room. This cuts visual, auditory, tactile, thermal and gravitational input.
• Chamber REST: the client stays alone in a dark, quiet room, usually for up to 24 hours.

Proposed mechanism. The Laureate group's account is that taking away external input makes internal bodily signals, such as heartbeat and breathing, easier to notice. On that view, floating gives anxious people, especially those who fear bodily sensations (high anxiety sensitivity), a safe setting to meet interoceptive signals while the body is deeply relaxed. In their study, floating reduced state anxiety and raised serenity, and lowered blood pressure compared with watching a film [source: Feinstein et al. 2018, interoception paper]. Suedfeld's account stressed relaxation and lowered arousal in flotation, and increased openness to new information in chamber REST [source: Suedfeld, UBC REST page; chamber details uncertain, see 4.12]. John C. Lilly built the first water-immersion isolation tank in 1954 at the US National Institute of Mental Health. He held that the brain is a "programmed biocomputer" whose "internal programming" a person could explore and change in the tank. This is Lilly's own theory, not an established mechanism [source: Wellcome Collection; Wikipedia, Isolation tank].

History and status. Lilly's first design fully submerged the subject in body-temperature water. After leaving NIMH in the late 1950s, he developed the horizontal Epsom-salt float [source: Wellcome Collection]. Commercial tanks were first sold in 1972 by Glenn Perry, who had attended a workshop of Lilly's [source: Wikipedia]. Lilly later combined tank sessions with psychoactive drugs. This is history only: it is not part of any clinical protocol, it is not for use, and no details are given here [uncertain: Lilly's own books].

Flotation is not a drug or medical device treatment. In the jurisdictions checked, commercial float centres are regulated as aquatic or public-health facilities. Western Australia, for example, applies its aquatic-facilities Code of Practice, requiring water filtration and disinfection, a call alarm and light inside the tank, and an age minimum of 16 [source: HealthyWA]. Clinical use for anxiety and depression is still investigational [source: Laureate RCT preprint].

2. Framework

This framework is put together from the trial protocols, because no single manual covers it [source: Laureate RCT preprint; Feinstein et al. 2018; Kjellgren & Westman 2014; [synthesis] for phase labels].

Chamber REST (Suedfeld): usually one stay of 24 hours or less in a furnished dark room, often with therapeutic support. It was used for smoking, overeating, alcohol problems, phobias and other targets [source: Malůš et al. 2016; Suedfeld reference list]. It needs a dedicated, staffed facility, and no current open protocol was found [uncertain].

3. Guiding principles

• Voluntariness and free exit. The client can open the door or leave the pool, call staff and stop at any time. Practical meaning: rehearse the exit before the first float, and say plainly that stopping early is fine [source: HealthyWA; Feinstein 2018; Kjellgren & Westman 2014; Malůš et al. 2016: "nobody should be forced"].
• Neutral, non-alarming framing. Suedfeld found that standard introductions that stressed a panic button primed people to expect a bad reaction, and that restricting movement caused stress of its own. Practical meaning: present safety features as routine conveniences, not as signs of danger [source: Suedfeld, UBC REST page].
• Minimal instruction. In the Laureate protocols the only guidance was stillness and staying awake, with no instruction about how to spend the time. Practical meaning: don't load the float with tasks unless you are deliberately running a variant [source: Feinstein 2018; Laureate RCT].
• Minimise sensory noise. Unscented products, a shower first, no eating or drinking during the float, a sound-, light- and vibration-isolated room, and water and air at skin temperature. Practical meaning: check the facility, not just the client [source: Feinstein 2018].
• Screen first, and conservatively. Use published exclusions and refer for medical clearance where general health guidance says so. Practical meaning: don't book a float for someone with psychosis, bipolar disorder, epilepsy or active suicidal intent [source: Feinstein 2018; Laureate RCT; HealthyWA].
• Sober floats only. No alcohol or drugs. Sedating medicines raise the risk of drowning. Practical meaning: check the medication list and same-day use before every session [source: HealthyWA; Laureate RCT].
• Measure every session. Laureate checked adverse effects and positive and negative experiences after every float. Practical meaning: use a brief checklist and verbal enquiry each time [source: Laureate RCT].
• Client preference matters. Pool vs tank, and fixed vs chosen schedule. The client-chosen-schedule arm had the lowest dropout, though the difference was not significant. Practical meaning: offer choices where safe [source: Laureate RCT].
• Adjunct, not replacement. REST may deepen or speed up therapy but does not replace it. It should sit in a protected frame with preparation and integration. Practical meaning: keep the main treatment going [source: Malůš et al. 2016].
• Attribute the metaphysics. Lilly's "biocomputer" and "psychic liberation" ideas, and any "transcendence" framing (Suedfeld 1985 used the word in a title), belong to their authors. Practical meaning: present the float to clients as relaxation and body awareness, and explore their spiritual readings respectfully without endorsing them [source: Wellcome Collection; Suedfeld reference list; [synthesis]].

4. Intervention inventory

The trials' interventions are environmental and procedural. Example language is illustrative unless it is quoted and cited.

4.1 Medical and psychiatric screening

• Purpose / when: before any float course, to rule out people for whom salt water, darkness, isolation or deep relaxation are unsafe.
• Steps:
  1. Take a psychiatric history. Laureate excluded bipolar disorder, schizophrenia, eating disorders (in the anxiety and depression trial), active suicidality with intent or plan, current inpatient treatment, and moderate or worse substance use disorder. Diagnoses were checked with a structured interview [source: Feinstein 2018; Laureate RCT].
  2. Take a neurological history. Laureate excluded epilepsy and other neurological conditions; the 2018 study also listed stroke, severe brain injury, Parkinson's disease and dementia [source: Feinstein 2018; Laureate RCT].
  3. Check physical and skin health. Exclude skin conditions or open wounds that would sting in salt water, and anyone who cannot swim, is uncomfortable in water, or cannot lie comfortably in a shallow pool. Laureate also excluded pregnancy, confirmed by urine test [source: Feinstein 2018; Laureate RCT].
  4. Apply public-health guidance. Float centres advise against floating with epilepsy, kidney disease, low blood pressure, open wounds or ulcers, claustrophobia, or any contagious illness, including diarrhoea or gastroenteritis and for 14 days afterwards. Under-16s are not admitted. Clients who are pregnant, or who have heart conditions, asthma, severe psoriasis or eczema, psychosis, or sensitivity to sulphate, magnesium, chlorine or bromine, should see a health practitioner first [source: HealthyWA].
  5. Review medicines. Laureate excluded daily benzodiazepine use. People using benzodiazepines or opioids only as needed had to abstain for 24 hours before each float. Medication or psychotherapy had to be stable for at least 8 weeks (6 weeks in 2018). Sedating medicines raise the risk of drowning [source: Laureate RCT; Feinstein 2018; HealthyWA].
  6. Use clinical judgement on items the sources don't list but that follow from the method [synthesis]: severe untreated trauma or dissociative disorder without stabilisation; uncontrolled cardiovascular disease or recent surgery (refer for medical clearance); severe hearing or vision loss affecting orientation; and a history of solitary confinement, abduction or other trauma tied to darkness or restraint.
• Example language (illustrative): "Before we book anything, I need to go through some health questions. The float is gentle, but salt water, darkness and being alone don't suit everyone."
• Watch for: clients playing down symptoms to get access; panic disorder with marked claustrophobia (HealthyWA says not recommended; Laureate included panic disorder, so decide case by case, see 5.2); eating-disorder history (see 5.10).

4.2 Informed consent and expectation-setting

• Purpose / when: at the information meeting, before orientation.
• Steps:
  1. Explain the environment, how long sessions last, how many there are, and that the client may stop at any time. Make clear that taking part is voluntary and confidential [source: Kjellgren & Westman 2014].
  2. Describe common experiences neutrally: deep relaxation, changes in time sense, stronger awareness of heartbeat and breathing, brief colours or shapes in the dark, and feeling detached. Describe common nuisances: dry mouth, itching, salt stinging the eyes or small cuts, and sometimes nausea on a first float [source: Laureate RCT; HealthyWA].
  3. Mention that fear or panic-like feelings sometimes come up early and usually pass. In the 2018 study one participant first thought they were having a panic attack and then relaxed [source: Feinstein 2018].
  4. Frame safety features as routine, not alarming [source: Suedfeld, UBC REST page].
  5. Get consent and record it. Laureate used formal written consent within an IRB-approved trial; Karlstad recorded verbal consent [source: Kjellgren & Westman 2014; Laureate RCT].
• Example language (illustrative): "Most people find it very relaxing. Some notice their heartbeat more, or see a few colours in the dark. That's normal, and you can sit up and leave whenever you want."
• Watch for: expectations of cure or of mystical experience. Gently correct these to "relaxation and body awareness" [synthesis].

4.3 Facility orientation and exit rehearsal

• Purpose / when: at the first visit, before the first float.
• Steps:
  1. Walk the client through the float centre [source: Kjellgren & Westman 2014].
  2. Show them how to open and close the tank door from inside, and where the internal call alarm and light are. In Western Australia operators must do this before the first session [source: HealthyWA].
  3. Show them the intercom to staff, and explain how the end of the session will be signalled. Laureate played music through speakers [source: Feinstein 2018].
  4. Offer an open pool with no enclosure, which the client can get out of at any time, or an enclosed tank, according to preference [source: Feinstein 2018; Laureate RCT].
• Example language (illustrative): "Here's the handle, and here's the call button. Try opening it yourself now, so your hands know how."
• Watch for: hesitancy at the door. That suggests choosing the open pool [synthesis].

4.4 Same-day checks and preparation

• Purpose / when: before every float.
• Steps:
  1. Check for alcohol and drugs. Laureate used a urine drug screen and breathalyser before every session and excluded anyone who tested positive. Commercial centres refuse intoxicated clients [source: Laureate RCT; HealthyWA].
  2. Confirm the client is not acutely ill and has no new cuts, fresh shaving or sunburn [source: HealthyWA].
  3. The client eats several hours beforehand and does not eat or drink during the float [source: Feinstein 2018].
  4. The client showers with unscented products before entering [source: Feinstein 2018; HealthyWA].
  5. Take brief pre-session ratings. Laureate measured state anxiety, serenity and other mood ratings, and blood pressure in one study [source: Feinstein 2018].
• Example language (illustrative): "Quick check-in: anything to drink or any medication today that we haven't talked about?"
• Watch for: same-day use of sedatives or other substances. If present, don't float (see 5.9).

4.5 Introductory or habituation float

• Purpose / when: a first float that lets the client get used to the setting before therapeutic sessions or measurement begin.
• Steps:
  1. Schedule one float, which can be shorter (Laureate's first float was 60 min) [source: Feinstein 2018]. Some studies used two habituation sessions [source: 2023 flotation-REST review, citing Schulz & Kaspar 1994].
  2. Debrief as in 4.10 and decide together whether to continue.
• Example language (illustrative): "Think of today as getting to know the pool. There's nothing to achieve."
• Watch for: novelty effects. Positive ratings (relaxation, serenity) fell across sessions in the Laureate RCT, so the first float may feel the most striking [source: Laureate RCT].

4.6 Standard pre-float instruction

• Purpose / when: immediately before each float.
• Steps:
  1. Give a short, consistent instruction set. Laureate read a scripted instruction asking participants to "try to find a place of stillness of both body and mind" and to stay awake, keeping movement and speech to a minimum [source: Feinstein 2018].
  2. Give no further guidance on what to do with the time. Laureate explicitly gave none [source: Feinstein 2018].
  3. Use the same instructions every session. In the RCT, all arms emphasised stillness and wakefulness; the full set is in a supplement not drawn on here [source: Laureate RCT; uncertain for exact wording].
• Example language: paraphrase the Laureate instruction in your own words, for example (illustrative): "Let your body and mind settle as much as you can, try to stay awake, and keep movement and talking to a minimum."
• Watch for: clients who ask for a task. Offering one is a deliberate departure from the protocol; mark it as a variant [synthesis].

4.7 Environment set-up (therapist or facility check)

• Purpose / when: before every float, especially in a commercial centre.
• Steps: confirm the following [source: Feinstein 2018; Laureate RCT; Kjellgren & Westman 2014; HealthyWA]:
  • Water and air at skin temperature (about 35 °C).
  • Water saturated with Epsom salt so the client floats with their face clear.
  • Shallow water (about 28 cm in the Laureate pool).
  • A room that is lightproof, soundproof and free of vibration.
  • Filtration and UV-based disinfection between users.
  • A working call system.
  • A no-slip floor.
  • An end-of-session signal.
  • No pumped oxygen (an operator rule in WA).
• Example language: not applicable.
• Watch for: the water feeling too cool or too warm, smells, or noise leaking in. These break the low-stimulation conditions [synthesis].

4.8 The float session and in-session monitoring

• Purpose / when: the core intervention.
• Steps:
  1. Set the session length for the version you are following: 60 min fixed (Laureate RCT), up to 90 min (Feinstein 2018), a client-chosen length of up to 2 h (Laureate preferred-schedule arm), or 45 min (Karlstad) [sources as cited].
  2. The client enters the water, lies on their back and settles. Light goes off: the room is completely dark once the door is sealed and the pool light is off [source: Feinstein 2018]. Earplugs are optional in many tank set-ups [source: Malůš et al. 2016].
  3. Staff stay reachable by intercom or call alarm. Safety is monitored in ways that keep the client's privacy [source: HealthyWA; Feinstein 2018].
  4. The end is signalled (music, in Laureate's case). The client gets out slowly [source: Feinstein 2018].
  5. Physiological monitoring, such as the waterproof-cuff blood pressure readings in the 2018 study, belongs to research or medical staff. It is not needed in routine practice [source: Feinstein 2018].
• Example language (illustrative, before the door closes): "I'll be right outside. The call button is by your right hand. See you when the music starts."
• Watch for: early exits. In 2018 most people floated the full time; a few left when the end music began. Repeated early exits call for review [source: Feinstein 2018; [synthesis]].

4.9 Scheduling the course

• Purpose / when: at planning, and reviewed during the course.
• Steps:
  1. Choose a schedule: 6 weekly sessions (Laureate fixed); 6 sessions within 12 weeks at least 24 h apart, timed by the client (Laureate preferred); or 12 sessions of 45 min about twice a week over 7 weeks (Karlstad) [source: Laureate RCT; Kjellgren & Westman 2014].
  2. Hold sessions at a consistent time of day where possible [source: Feinstein 2018].
  3. Plan follow-up reviews; Laureate used 6 weeks and 6 months [source: Laureate RCT].
• Example language (illustrative): "Would you rather fix one day a week, or book floats when you feel you need them, at least a day apart?"
• Watch for: dropout. Across the Laureate arms it was 16–24% in the pool arms and 32% in the chair arm over 6 sessions, with reasons mostly unrecorded [source: Laureate RCT].

4.10 Post-float recovery and debrief

• Purpose / when: straight after every float.
• Steps:
  1. Allow about 30 min to shower and rest before the client leaves [source: Kjellgren & Westman 2014].
  2. Ask about adverse effects. Laureate used a 43-item checklist plus verbal report, with free text for any item endorsed and a follow-up question on whether each experience felt positive or negative. Make your own short checklist; the trial instrument is not reproduced here [source: Laureate RCT].
  3. Repeat the pre-session ratings, about 30 min after the float [source: Feinstein 2018].
  4. Optionally use a body-map tracing and retrospective ratings of heartbeat, breath and other body sensations, as Laureate did [source: Feinstein 2018].
  5. Hold a short debrief interview [source: Feinstein 2018].
• Example language (illustrative): "What did you notice in your body? Was any of it uncomfortable, and did that change over the float?"
• Watch for:
  • Lingering detachment or disorientation. Clients may also notice smell, sound and light more strongly afterwards, which is reported as normal [source: HealthyWA].
  • Nausea.
  • Hallucination-like imagery, mostly colours and shapes, which was usually neutral or positive in the trial [source: Laureate RCT].
  • Disturbing memories (see 5.4).

4.11 Linking floats to interoceptive work in therapy [synthesis]

• Purpose / when: for clients with high anxiety sensitivity or panic, using the Laureate rationale that the float lets people meet heartbeat and breath sensations while relaxed [source for rationale: Feinstein 2018]. The procedure itself is [synthesis]; no source describes a combined protocol.
• Steps:
  1. Hold the therapy session on the day of a float or the day after.
  2. Review the body map: which sensations appeared, how the client read them, and how their meaning changed (for example, "heart pounding = danger" becoming "heart beating = just my body").
  3. Tie this to the client's ongoing treatment, for example CBT for panic.
• Example language (illustrative): "You noticed your heartbeat and, after a while, it stopped feeling dangerous. What do you make of that?"
• Watch for: turning the float into avoidance ("I can only relax in the tank"). Plan how calm states carry over into daily life.

4.12 Chamber REST (Suedfeld) — specialist variant

• Purpose / when: historical and specialist. Suedfeld and colleagues used it for smoking cessation, weight reduction, alcohol problems, snake phobia, claustrophobia, essential hypertension and children with autism [source: Suedfeld reference list; UBC REST page].
• Steps (general):
  1. The client stays alone in a dark, quiet room with a bed, a toilet and often an armchair. Food and drink are provided as needed.
  2. The stay lasts up to 24 hours, often with therapeutic support [source: Malůš et al. 2016].
  3. Suedfeld reported that fewer than 10% ended a 24-hour stay early because of unpleasant experiences [source: Malůš et al. 2016, citing Suedfeld 1980].
  4. Targeted messages or information were apparently presented during some addiction applications, but the content, timing and format were not confirmed in the sources [uncertain].
• Example language: not given; no sourced language was found.
• Watch for: only consider chamber REST inside a staffed research or specialist programme. It is not an office procedure.

4.13 Mental rehearsal during REST

• Purpose / when: Suedfeld's sports studies found that tasks which benefit from mental rehearsal improved more when the rehearsal happened in the tank [source: UBC REST page]. Using this clinically, for example for imagery rehearsal of a feared situation or a new skill, is [synthesis].
• Steps [synthesis]:
  1. Agree on one short rehearsal scenario before the float.
  2. The client rehearses it in the middle part of the float, then returns to stillness.
  3. Debrief afterwards.
  4. Mark this as a departure from Laureate's no-instruction protocol.
• Example language (illustrative): "Once you've settled, picture walking into the meeting calmly, two or three times, then just let it go."
• Watch for: distress during imagery when the client is alone. Don't use it for trauma memories (see 5.4).

4.14 Extended darkness stay — named variant, not office practice

• Purpose / when: a Czech research variant ("Darkness Therapy") with week-long stays [source: Malůš et al. 2016].
• Steps (general):
  1. The client stays in a windowless house with no light sources or devices. Meals arrive at set times after a bell.
  2. A one-way intercom connects to staff, and there is an emergency light and a spare key.
  3. A therapist visits daily for 30–45 min.
  4. At the end the client readjusts to daylight gradually, using sunglasses.
  5. Screening covered psychopathology, use of psychiatric medicines, acute illness and bleeding.
• Watch for: in pilot work participants reported anxiety, unpleasant memories, the return of repressed experiences, unpleasant dreams and physical discomfort. How well clinical populations tolerate this is unknown [source: Malůš et al. 2016].

4.15 Chair-REST as a lower-intensity option

• Purpose / when: this was Laureate's comparator: a reclining zero-gravity chair in a dark, quiet room, fully clothed, with the same schedule and instructions [source: Laureate RCT]. Offering it to clients who can't use water (skin conditions, fear of water) or as a step towards floating is [synthesis].
• Steps: lie back in the chair in a darkened room, with the same instructions as 4.6 and the same debrief as 4.10.
• Watch for: in the trial it had the highest dropout and lower serenity ratings than the pool [source: Laureate RCT].

4.16 Harm-reduction consultation for clients who float commercially [synthesis + HealthyWA]

• Purpose / when: a client is floating, or plans to, at a commercial centre outside therapy.
• Steps:
  1. Screen using 4.1.
  2. Advise floating sober, with no alcohol, drugs or sedating medicines beforehand. A 2018 drowning in an isolation tank was followed by an autopsy that found ketamine [source: Wikipedia, Isolation tank; secondary].
  3. Advise choosing a licensed centre with a call alarm and proper disinfection.
  4. Suggest an open pool or leaving the door ajar for a first float.
  5. Bring experiences into session.
• Example language (illustrative): "If you go, go sober and choose a place that shows you the call button and exit first."
• Watch for: floats used to manage a crisis or in place of care that is needed.

5. Handling problems

Documented adverse effects [source: Laureate RCT; HealthyWA; Feinstein 2018; Malůš et al. 2016; 2023 review]:

• Dry mouth, the most common pool-related effect, possibly from the salt.
• Itching.
• Fear or panic, rated more negatively in the preferred-schedule pool arm than in chair-REST.
• Visual hallucination-like imagery and detachment, usually rated neutral or positive.
• Nausea on first floats.
• Salt stinging the eyes or cuts.
• Heightened senses afterwards.
• One ear infection after a float, judged unrelated.
• In early tank designs, discomfort and fear, which Lilly and Shirley (1961) reported.
• In longer darkness stays: anxiety, unpleasant memories and dreams.

The Laureate RCT reported no serious adverse events attributed to floating. One pool-arm participant attempted suicide before follow-up; investigators judged this unrelated.

5.1 First-float fear or panic-like surge

• Sourced: fear and panic were among the negative experiences recorded. In the 2018 study a participant first thought they were having a panic attack, then relaxed [source: Laureate RCT; Feinstein 2018].
• Response [synthesis]:
  1. Before the float, agree a plan: sit up, turn on the light or open the door, use the intercom, breathe slowly, then choose whether to lie back down.
  2. Afterwards, normalise and reframe what happened as noticing body sensations.
  3. Next time use the open pool or a shorter float.
  4. Never pressure the client to stay in.

5.2 Claustrophobia and fear of dark or water

• Sourced: float-centre guidance says floating is not recommended with claustrophobia [source: HealthyWA]. Laureate offered an open, unenclosed pool [source: Feinstein 2018]. Suedfeld wrote on using sensory deprivation to treat claustrophobia [source: Suedfeld reference list; paper uncertain].
• Response [synthesis]: start with chair-REST or an open pool; consider a dim light or open door at first, explaining that this departs from protocol; build up gradually. Severe claustrophobia is better treated with standard graded exposure first.

5.3 Hallucinations, depersonalisation or detachment

• Sourced: colours and shapes, and feeling "in my own world", were usually rated neutral or positive [source: Laureate RCT].
• Response [synthesis]: normalise them as effects of the dark. Ask about distress, how long it lasted, and whether the client could tell it was imagery rather than reality. If you see persistent derealisation, paranoid ideas, or experiences the client believed were real, stop the course and do a psychiatric assessment. Psychosis and bipolar disorder are exclusions [source: Feinstein 2018; HealthyWA].

5.4 Trauma memories or disturbing material

• Sourced: unpleasant memories and the return of repressed experiences were reported in extended darkness [source: Malůš et al. 2016]. PTSD was an inclusion diagnosis in the 2018 Laureate cohort [source: Feinstein 2018].
• Response [synthesis]: make sure the client is stabilised before floating. Before each float, agree a grounding routine: touch the pool edge, open your eyes, use the call button. Afterwards process the material in therapy, not alone at home. Pause floats if intrusions increase. Don't use floats for unstructured trauma processing.

5.5 Suicidality and deterioration

• Sourced: active suicidality with plan or intent was an exclusion. A suicide attempt occurred during follow-up in the RCT [source: Laureate RCT].
• Response [synthesis]: do a standard risk assessment at baseline and at every review. Keep the main treatment and the safety plan going; floating is an adjunct. Re-screen after any crisis before floating again, and make sure the client is not left isolated straight after a float if their mood is low.

5.6 Stuck or declining benefit

• Sourced: positive ratings fell across six sessions [source: Laureate RCT]. Sessions longer or shorter than 60 min have not been tested [source: Laureate RCT].
• Response [synthesis]: explain this habituation in advance. Shift the focus from the novelty of the float to what carries into daily life (see 4.11). Consider the client-chosen schedule. If the float adds little, stop it and keep core therapy.

5.7 Non-adherence and dropout

• Sourced: dropout was 16–32% depending on arm. Possible reasons include unmet expectations, cost and time; trial participants were paid, so real-world feasibility is unknown [source: Laureate RCT].
• Response [synthesis]: explore cost and travel early; offer preference-based scheduling; check expectations after the first float; and treat missed floats as information, not failure.

5.8 Physical problems

• Salt in eyes: this causes discomfort [source: HealthyWA]. [synthesis] Keep the face dry and have fresh water and a towel within reach.
• Itching, dry mouth, stinging cuts: expected [source: Laureate RCT]. [synthesis] Cover small cuts if the centre allows; drink water before and after rather than during, in line with Laureate's no-drinking rule.
• Nausea on a first float [source: HealthyWA]: [synthesis] get up slowly and sit before standing.
• Low blood pressure: a listed contraindication [source: HealthyWA]. In an anorexia nervosa study no orthostatic hypotension was found [source: 2023 review, citing Khalsa et al. 2020]. [synthesis] Rise slowly anyway.
• Falling asleep: buoyancy keeps the client afloat [source: HealthyWA]. The protocol instruction is to stay awake [source: Feinstein 2018].
• Infection: don't float with any contagious illness, or for 14 days after gastroenteritis [source: HealthyWA].

5.9 Intoxication or sedative use

• Sourced: intoxicated clients are not permitted to float, and sedating medicines raise the risk of drowning [source: HealthyWA]. Laureate tested before every session [source: Laureate RCT].
• Response [synthesis]: cancel and reschedule without shaming the client; review their substance use; involve the prescriber about sedating medicines. Never let a float be combined with drug use.

5.10 Eating disorders and body image

• Sourced: eating disorders were excluded from the Laureate anxiety and depression trial, and the group studied anorexia nervosa separately [source: Laureate RCT; 2023 review]. That protocol is not drawn on here [uncertain].
• Response [synthesis]: only offer floating within a specialist eating-disorder programme with medical oversight. Being unclothed and noticing the body may trigger distress.

5.11 Ruptures and frame problems [synthesis]

• Typical ruptures:
  • The client feels abandoned in the dark, or feels the therapist "outsourced" care to a tank.
  • Disappointment when floats don't deliver expected peak experiences.
  • Conflict over the therapist screening them out.
• Responses:
  • Name the float as an adjunct and keep regular sessions.
  • Explore the client's expectations and any spiritual meanings they bring, attributing them (Lilly's "biocomputer" view is his own theory).
  • Explain exclusions as safety decisions, and offer alternatives such as relaxation training, chair-REST or standard interoceptive exposure.
• Dual roles: if you own or receive referral income from a float centre, disclose it.

5.12 Historical and spiritual claims clients bring [synthesis]

• Clients may cite Lilly's later work, mixing the tank with drugs, or commercial claims of "enlightenment". Explain that these are historical or promotional claims, not clinical protocols, and that clinical floats are always drug-free.
• Health claims for floatation are often exaggerated [source: Wikipedia, Isolation tank; secondary].

Sources

Sources:

• Feinstein et al. 2018, Floatation-REST, interoceptive awareness and anxiety sensitivity (PDF; title as listed by host)
• A randomized controlled safety and feasibility trial of floatation-REST in anxious and depressed individuals (medRxiv preprint)
• Systematic review of flotation-REST literature (medRxiv preprint, 2023)
• Suedfeld's Research Involving Extreme & Unusual Environments: REST (UBC)
• Suedfeld REST reference list (UBC)
• Kjellgren & Westman 2014, Beneficial effects of treatment with sensory isolation in flotation-tank (BMC Complementary and Alternative Medicine)
• Floatation tanks (HealthyWA, Government of Western Australia)
• Malůš, Kupka & Dostál 2016, Existential meaning in life, mindfulness and self-esteem in the context of restricted environmental stimulation (Psychologie a její kontexty, PDF)
• Wellcome Collection article on Lilly and the isolation tank
• Isolation tank (Wikipedia; secondary)

Further reading (not drawn on; from reference lists):

• Suedfeld, P. (1980). Restricted environmental stimulation therapy. In R. Herink (Ed.), The Psychotherapy Handbook.
• Suedfeld, P., & Borrie, R. A. (1999). Health and therapeutic applications of chamber and flotation REST. Psychology and Health, 14, 545–566.
• Suedfeld, P. (1990). Restricted environmental stimulation and smoking cessation: a 15-year progress report. International Journal of the Addictions, 25, 861–888.
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• ClinicalTrials.gov NCT03899090 and NCT03610451 (pages did not render).