Table 2: Sauna studies of rheumatological disease/chronic pain/depression.

Study characteristics Study sample Intervention ComparatorsHealth effectsAdverse side effects
Author & yearLevel of evidenceDesignPop/countrySauna typeDurationComparator/
controls
Outcome
measures
Positive/
negative/
negligible
None/mild/
moderate/
severe

2015
Kanji et al. [50]
IRCTChronic tension headache/New Zealand37Multiple types, sauna voucher cards8 weeksControl group received advice and educationNPRS (numeric pain rating scale), BDI (Beck Depression Inventory), HDI (Headache Disability Index)Positive,
44% reduction in HA intensity in 6 weeks of treatment arm. Mean change in headache intensity between sauna and control group = 1.27 points (95% CI 0.48–2.07; = 10.17; df = 1,117; )
None

2005
Masuda et al. [51]
IRCTChronic pain/Japan46FIR4 weeksControl group received same course of behavioural counselling, CBT, rehabilitation, and exercise therapyVAS for pain; pain behaviour assessment by researchers with 11-item questionnaire; Zung SDS (self-rating depression scale); anger scoring with CMI (Cornell Medical Index); sleep quality with simple 0–10 scoring; degree of satisfaction of treatments with simple numerical scoring; return to work 2 years after interventionPositive,
increased likelihood of return to work 2 years later (); decrease in anger scoring in sauna group compared to control (4.5 ± 1.1 to 2.2 ± 1.6, )
Moderate,
2 patients excluded -could not tolerate sauna - acute bronchitis and claustrophobia

2005
Masuda et al. [52]
IRCTMild
depression/
Japan
28FIR4 weeksControl group received placebo,
45 min bedrest at 24°C and postrest shower in addition to the same rehab programs, physical therapy, occupational therapy
Somatic complaints with CMI (Cornell Medical Index);
Zung SDS (self-rating depression scale); VAS for hunger and relaxation; plasma levels of ghrelin, glucose, catechol-amines; daily caloric intake.
Positive, improved somatic complaints (), improved hunger scores (), and improved relaxation scores () in sauna group compared to control group. Plasma ghrelin concentrations and daily caloric intake increased in sauna group (, and , , respectively); = Student 2-tailed -testNone

2009
Oosterveld et al. [53]
III2 single-group
(side-by-side)
intervention pilot trials
Rheumatoid arthritis (RA) and
ankylosing spondylitis (AS)/The Netherlands
34FIR4 weeksNo control group; two groups receiving same sauna interventionVAS, EPM-ROM (Escola Paulista de Medicina range of motion), DUTCH-AIMS (Dutch arthritis impact measurement scales), BASMI (Bath Ankylosing Spondylitis functional index of range of motion), BASDAI (Bath Ankylosing Spondylitis disease activity index); serum ESRPositive,
pain and stiffness decreased in RA () and AS () groups during sauna sessions only.
Mild-
12−24% scoring uncomfortable on well-being scores during beginning of sauna

2015
Amano et al. [54]
IIIClinical study with control group, pilot trialFemales with chronic fatigue syndrome/myalgic encephalomyelitis/Japan15FIR8 weeks6/15 chose not to undergo sauna interventionSF-36 survey; SRQ-D (brief self-rating questionnaire for depression); STAI (state-trait anxiety inventory questionnaire)Positive,
7/9 in sauna group improved during sessions; 4/9 were still improved at follow-up 9−40 months afterwards; 2/9 non-responders.
3/6 controls receiving usual treatment improved at follow-up
Moderate-
heat intolerance in most participants,
protocol changed.

2015
Soejima et al. [55]
IIISingle-group clinical studyChronic fatigue syndrome (CFS)/Japan10FIR4 weeksNo control groupNumerical rating scales for fatigue and POMS (profile of mood states) questionnairePositive, decreased fatigue (), improved POMS scores for anxiety (), depression (), fatigue () and performance status () after saunaNone

2011
Matsumoto et al. [56]
IIISingle-group clinical studyFemales with fibromyalgia and autoimmune disorders/Japan44FIR12 weeksSauna only one part of intervention; combined with underwater exercise therapy; no control groupVAS-visual analogue scale; no. of tender pts on clinical exam; FIQ (fibromyalgia impact questionnaire); SF-36 quality of life questionnairePositive, reduced VAS pain scores (); fewer # of tender pts (); reduced symptoms based upon FIQ (); improved quality of life on SF-36 questionnaire (–0.05) after combined sauna + underwater exercise therapyNone

FIR = Far-infrared sauna; ESR = erythrocyte sedimentation rate; VAS = visual analogue scale; CBT = cognitive behavioural therapy.