Seventy-five treatment-seeking adults entered a careful test of deep rest and the simplest number from the trial was about showing up. People assigned to the two water-based groups completed 85% and 89% of their six planned sessions. People assigned to chair-based rest completed 74%.
The PLOS ONE study, published in June 2024, tested whether repeated sessions of Reduced Environmental Stimulation Therapy by floating could be practical and safe for people with both anxiety and depression. The trial was led by Meredith M. Garland and colleagues, with participants recruited through the Laureate Institute for Brain Research and the local community.
The researchers framed the work as an early safety and feasibility trial. The results do not prove that floating treats anxiety or depression. They do show that many people in this outpatient sample were able to complete repeated sessions and that the study team recorded no serious adverse events tied to any of the three rest conditions.
Six sessions tested repeated floating
The intervention studied here is called floatation-REST, short for Reduced Environmental Stimulation Therapy. In the pool version, a person floats on dense saltwater in a quiet room with little light and sound. The water is warmed near skin temperature and Epsom salt helps the body float with little effort.
Garland and colleagues wrote that earlier studies had found single float sessions to be safe and well tolerated in people with anxiety and depression. A single session can show what happens during one visit, while repeated sessions raise a different question: whether people will return, stay in the setting long enough and avoid serious safety problems across weeks.
The new trial was registered at ClinicalTrials.gov as NCT03899090. It used a randomized parallel design, meaning participants were assigned to one of three conditions and then followed through the planned sequence of visits.
The team screened 1,715 people before randomizing 75 adults. Each participant had anxiety and depression symptoms and each was assigned to complete six rest sessions. The study also included follow-up visits at six weeks and six months, although the main article focused on safety, tolerability and feasibility rather than claiming a clinical cure.
Three groups made the comparison clearer
One group received pool-REST, with six weekly one-hour float sessions. Participants could choose an open or enclosed circular pool and each pool was located in a room designed to limit outside light and sound.
A second water group received pool-REST preferred. The same floating pools were used, but participants could choose session length up to two hours and could schedule the six sessions more flexibly within a 12-week period, with at least 24 hours between sessions.
The comparison group received chair-REST. Participants reclined in a Zero Gravity chair for six weekly one-hour sessions in a dim and quiet room. The chair setting copied some parts of floating, including a still body position and reduced stimulation, while leaving out the warm saltwater pool.
Using chair-based rest helped the researchers compare floating with another quiet rest setting instead of comparing it only with no treatment. The chair room still allowed more outside light and sound than the pool rooms and participants remained fully clothed at normal room temperature.
The water groups crossed the adherence mark
The primary feasibility target was an 80% adherence rate to the assigned sessions. The two water groups passed that mark. Mean adherence was 85% for the fixed pool group, equal to an average of 5.1 sessions out of six. The flexible pool group reached 89%, equal to an average of 5.3 sessions.
The chair group averaged 74% adherence, equal to 4.4 sessions. The authors reported that the chair group fell below the planned 80% mark, while the two pool groups met it. Because this was a small early-phase trial, the paper cautioned that the observed differences in adherence were not tested as proof that one format is clinically better than another.
Dropout patterns also favored the water groups numerically, especially before the first intervention session. After randomization and before treatment began, dropout was 16% in chair-REST, 4% in pool-REST and 0% in pool-REST preferred. Across the six-session intervention, dropout reached 32% in chair-REST, 24% in pool-REST and 16% in pool-REST preferred.
A survival analysis did not find a significant difference in dropout among the three groups. The study also took place during the COVID-19 pandemic and two participants were withdrawn by investigators after shutdowns prevented completion within the planned timing rules.
Flexible floating lasted longer
Session duration gave another clue about tolerability. Across the whole study, the team administered 373 rest sessions and 317 of them lasted at least 50 minutes. That means 85% of sessions reached most of the planned or chosen duration.
The fixed pool group averaged 53.0 minutes per session. The chair group averaged 58.4 minutes. The flexible pool group averaged 75.4 minutes, meaning participants who could choose longer floats often stayed beyond the one-hour schedule used in the other two groups.
Researchers reported that the flexible pool sessions were significantly longer than sessions in either the chair group or the fixed pool group. They also found no significant duration difference between the fixed pool and chair groups, which both had prescribed one-hour sessions.
The earlier single-session floatation study in PLOS ONE had suggested short-term reductions in anxiety and depressed mood after one float, while calling for larger controlled trials. The six-session trial answered a narrower next question by checking whether repeated exposure could be completed and monitored in a clinical sample.
Safety checks were central
Safety carried extra weight because floating changes the ordinary sensory environment. The rooms are quiet, the light is low and the body rests in warm, salty water. For some people, such a setting may feel calming. For others, stillness and reduced outside input can be uncomfortable.
The researchers screened for several risks before enrollment. Exclusion criteria included feeling uncomfortable in water, some skin problems or open wounds, certain neurological or psychiatric conditions, active suicidal intent with a plan, inpatient psychiatric treatment and moderate to severe substance use disorder. Before float sessions, urine and breath testing also checked for several drugs and alcohol.
Across the trial, the study recorded four adverse events and all were judged unrelated to the intervention. One chair-REST participant reported two migraine episodes with nausea on days of early rest sessions. One pool-REST participant with seasonal allergies reported an ear infection four days after a third session. Another pool-REST participant reported a suicide attempt the night before the six-week follow-up and was evaluated at a psychiatric emergency department.
The paper reported no serious adverse events associated with any rest condition. It also found that positive experiences were endorsed more often than negative ones and were rated with greater intensity. Negative experiences above the mild range were uncommon across the repeated sessions.
What the trial can and cannot show
The main result concerns safety and feasibility. Six sessions of floating appeared practical for many people in the sample, especially in the two pool groups and the repeated program did not produce serious intervention-related harms during the trial.
The study was small, with 25 people assigned to each condition. It was also an early-stage trial and the authors framed the results as a first step for testing repeated floatation in anxiety and depression. Larger randomized trials would be needed to test symptom change, compare benefits with established care and learn which patients are most likely to find repeated floating useful.
Costs and real-world access also remain open questions. Participants were compensated for research involvement, so the trial did not measure whether people would pay for six sessions, travel to a float center on their own, or keep using the approach outside a structured study.
For now, the finding is narrower and still useful. In a monitored outpatient trial, Meredith M. Garland and colleagues found that repeated floating could be delivered to adults with anxiety and depression with good adherence in both pool groups, acceptable tolerability and no serious adverse events linked to the intervention.
