Swedish Float Therapy Research: 7 Studies from Karlstad University

Updated: 12 October 2026 · Compiled by Float Vietnam

Quick answer: The Karlstad group in Sweden has published a long series of float therapy studies on stress-related muscle pain, stress, anxiety and sleep. A 2014 randomised trial in 65 working adults found lower stress, anxiety, depression and worst pain after 12 floats of 45 minutes over 7 weeks. A 2016 trial in 50 people with generalised anxiety found symptoms improved and the gains held at 6 months. These are small studies that need larger trials.

Who is the Karlstad group, and why did Sweden study floating?

If the Laureate Institute in the US is the hub of modern brain-focused float research, Karlstad University in central Sweden asked more everyday questions: can floating help people with stress, aches and poor sleep feel better? The group, led by psychologists Anette Kjellgren and Torsten Norlander with Sven-Åke Bood and many colleagues, has studied floating (flotation-REST, the restricted environmental stimulation technique) since around 2000. In Sweden, long-term stress and stress-related muscle pain are very common reasons for sick leave, so a deep, drug-free form of rest was of interest as prevention.

The group usually used closed float tanks or cabins, with sessions of about 45 minutes repeated over several weeks. This article summarises seven key studies by topic. Full citations (DOI, PMID) are in our float therapy whitepaper. To compare with the US team, read Laureate Institute float research.

Stress-related muscle pain: studies from 2001, 2005 and 2007

This is the topic the Karlstad group studied earliest and most closely. In 2001, Kjellgren and colleagues randomised 37 people with muscle tension pain to floating (9 sessions over 3 weeks) or a control group. The float group reported less of their most severe pain (milder pain did not change), lower levels of MHPG, a metabolite linked to the sympathetic nervous system, more optimism, less anxiety and depression, and easier sleep onset.

In 2005, Bood and colleagues asked a subtle question: do people feel better simply because they get more attention? They had 32 people with stress-related pain float over 6 weeks, with one group receiving much more staff attention and conversation than the other. Blood pressure, pain, anxiety, depression and stress fell, energy and optimism rose, and the gains were largely the same whatever the level of attention. The authors suggested that the deep relaxation response while floating, not just the attention, does most of the work.

In 2007 the same group compared 12 with 33 float sessions in 37 people. Twelve sessions already gave a clear improvement in pain and psychological measures, and going up to 33 added nothing more; only diastolic blood pressure was lower after 33. It is one of the few data points on “how many sessions are enough”. Read more on floatation therapy for pain and float therapy for back pain.

Stress in working adults: the 2014 trial

The group’s most cited trial is Kjellgren and Westman, published in BMC Complementary and Alternative Medicine in 2014. Sixty-five healthy working adults, mostly women (51 of 65), were randomised: 37 floated 12 times for 45 minutes over 7 weeks, and 28 waited their turn. Compared with the wait-list, the float group reported less stress, depression, anxiety and worst pain, and more optimism and better sleep quality; the wait-list group did not change. The authors described floating as a promising form of preventive health care. Limits: it was a pilot, all measures were self-reported, and participants knew which group they were in.

For how floating lowers stress, read floating reduces stress.

Generalised anxiety: the 2016 trial

In 2016, Jonsson and Kjellgren randomised 50 people with generalised anxiety disorder (GAD) to 12 float sessions or a wait list. The float group improved on GAD symptoms, sleep difficulties, emotion-regulation difficulties and mindfulness, and the gains were still present at the 6-month follow-up. Depression did not change significantly, and no negative effects were reported. The authors themselves stressed that a pilot trial cannot establish efficacy. Read more on float therapy and anxiety.

Insomnia and creativity: mixed results

In 2022, Norell-Clarke and colleagues (including Kjellgren) followed 6 people with insomnia through 12 floats of 45 minutes, using a single-case design. Three improved on their main insomnia symptom and two on sleep efficiency, with gains held at 2 months; total sleep time did not change, and two people did not improve. These are very early results. See float therapy for insomnia.

Back in 2003, Norlander, Kjellgren and Archer tested how floating affects creativity in two randomised experiments with 70 people in total. After floating, people tended to be more original and creative but did worse on a logic test; floating once or three times made no difference. An interesting hint for creative work, but not a firm conclusion. Read floating for creativity.

Summary and how to read the results

The table below collects seven key Karlstad studies. Strengths: one team, studies repeated over many years, a control group in most trials, and fairly consistent results on stress, pain and mood. Weaknesses: small samples, no blinding (people know they are floating), and mostly self-report questionnaires. That is why Float Vietnam presents floating as a form of deep rest that sits alongside professional care, not as a medical therapy.

Study	Design, participants	Main findings
Kjellgren et al. 2001	Randomised, 9 floats in 3 weeks, n = 37	Less worst pain; more optimism; easier sleep onset
Norlander et al. 2003	2 randomised experiments, n = 70	More original and creative; worse logic
Bood et al. 2005	Attention-controlled, 6 weeks, n = 32	Less pain, blood pressure, anxiety, stress; not driven by attention
Bood et al. 2007	Randomised, 12 vs 33 sessions, n = 37	12 sessions gave clear gains; 33 no better
Kjellgren & Westman 2014	Randomised wait-list, 12 × 45 min, n = 65	Less stress, anxiety, depression, pain; better sleep
Jonsson & Kjellgren 2016	Randomised wait-list, 12 floats, n = 50 with GAD	GAD symptoms and sleep improved, held at 6 months
Norell-Clarke et al. 2022	Single-case, 12 × 45 min, n = 6 with insomnia	Mixed: 3 of 6 improved on main symptom

For the wider picture, including US and Australian studies, read our float therapy evidence review.

Note: This page is for general information. Float therapy supports wellbeing but does not replace diagnosis or treatment by a doctor. If you have a medical condition, ask your doctor before floating.

Try it at Ōmni Space. Float Vietnam’s float rooms are at 16C Quoc Huong, Thao Dien, Ho Chi Minh City (Saigon), open daily 9:00–21:00. Book a float or read the float therapy FAQ.