Effects of Cold-Water Immersion on Health and Wellbeing: A Systematic Review and Meta-Analysis
Technology context Cold-water immersion in baths and showers at 7-15°C - closest available evidence for chilled plunge systems
Finding: Cold-water immersion produced a significant reduction in stress at 12 hours post-exposure, but also a significant acute increase in inflammation immediately and one hour afterwards.
Main limitation: Only 11 studies met inclusion, effects were time-dependent rather than sustained, and stress reduction was absent at every timepoint other than 12 hours.
Executive summary
This is the most current and most directly relevant synthesis for someone considering a cold plunge for general wellbeing rather than athletic recovery.
The reviewers searched for randomised trials in healthy adults undergoing cold-water immersion via cold shower, ice bath or plunge, at water temperatures of 15°C or below for at least 30 seconds. Eleven studies comprising 3,177 participants met the criteria. Immersions were performed in baths in ten studies and showers in one, at temperatures from 7°C to 15°C, for durations from 30 seconds to two hours.
The headline results are time-dependent and more nuanced than most marketing suggests. Inflammation increased significantly immediately after immersion (SMD 1.03, 95% CI 0.37-1.68, p<0.01) and at one hour (SMD 1.26, 95% CI 0.59-1.94, p<0.01) - an acute inflammatory response, not a reduction. Stress was significantly reduced at 12 hours post-immersion (SMD -1.00, 95% CI -1.40 to -0.61, p<0.01) but showed no significant effect immediately, at one hour, at 24 hours, or at 48 hours.
Meta-analysis found no significant effects on immune function immediately or at one hour, though narrative synthesis noted a 29% reduction in sickness absence among participants taking cold showers in one study. Improvements were also observed in sleep quality and quality of life, but not in mood.
The authors conclude that cold-water immersion delivers time-dependent effects with potential practical application for stress management and wellbeing, while noting the evidence base is constrained by few randomised controlled trials, small sample sizes, and a lack of population diversity.
Why this research matters
Almost all older cold-immersion research studied athletes recovering from exercise. This review asks the question an ordinary buyer is actually asking: what does regular cold immersion do for a generally healthy person?
It also directly contradicts a common marketing claim. Cold plunging is frequently sold as anti-inflammatory. In healthy adults, immediately after immersion, this meta-analysis found inflammation went up. That does not make cold immersion bad - an acute stress response followed by adaptation is a plausible and well-recognised pattern - but it does make the simple 'reduces inflammation' claim wrong as stated.
Study design
- Study type
- Systematic review with meta-analysis (PROSPERO CRD42024500591)
- Studies included
- 11
- Total participants
- 3,177
- Population
- Healthy adults aged 18 years and over
- Intervention
- Acute or long-term cold-water immersion via cold shower, ice bath or plunge
- Water temperature
- 7°C to 15°C (inclusion threshold ≤15°C)
- Immersion duration
- 30 seconds to 2 hours
- Delivery method
- Baths in 10 studies; shower in 1
- Comparator
- Varied by included trial
- Outcomes assessed
- Sleep, stress, fatigue, energy, skin health, immunity, inflammation, mental wellbeing, depression, anxiety, mood, concentration, alertness
- Analysis method
- Random effects models, standardised mean differences, RevMan 5.4
- Quality appraisal
- PEDro scale; mean score 6.4 (7 moderate quality, 4 high quality)
- Sex distribution
- Not reported in the source
What the researchers found
Inflammation. Significant increases immediately post-immersion (SMD 1.03, 95% CI 0.37-1.68, p<0.01) and at one hour (SMD 1.26, 95% CI 0.59-1.94, p<0.01), indicating an acute inflammatory response.
Stress. A significant reduction at 12 hours post-immersion (SMD -1.00, 95% CI -1.40 to -0.61, p<0.01). No significant effect immediately (SMD -0.09, 95% CI -0.45 to 0.63), at one hour (SMD -0.29, 95% CI -0.66 to 0.08), at 24 hours (SMD -0.06, 95% CI -0.50 to 0.38), or at 48 hours (SMD 0.09, 95% CI -0.28 to 0.46).
Immune function. No significant meta-analysed effect immediately (SMD -0.16, 95% CI -0.82 to 0.51) or at one hour (SMD -0.18, 95% CI -1.09 to 0.74). Narrative synthesis noted longer-term signals including a 29% reduction in sickness absence among cold-shower participants.
Sleep and quality of life. Improvements observed. Mood. No improvement observed.
What the results mean
A standardised mean difference of around 1.0 is conventionally read as a large effect, and -1.00 for stress at 12 hours is a substantial figure. The catch is that it appears at one timepoint only. An effect present at 12 hours and absent at 1, 24 and 48 hours is either a real but transient phenomenon or a chance finding among many comparisons - and with 11 studies it is difficult to distinguish the two.
The inflammation result is the most useful thing here for a buyer. Cold immersion produced an acute inflammatory rise in healthy adults. That is consistent with cold as a stressor to which the body adapts, and it is inconsistent with the way the technology is usually marketed.
What is reasonably supported: cold immersion has measurable short-term physiological and psychological effects, some of which look useful for stress and sleep. What is not: any claim of sustained, general anti-inflammatory benefit.
What this study does not prove
- It does not establish that cold-water immersion reduces inflammation. In healthy adults it found the opposite acutely.
- It does not establish sustained stress reduction. The effect appeared at 12 hours and at no other measured timepoint.
- It does not establish immune benefit. The meta-analysed immune outcomes were not significant; the sickness-absence figure comes from narrative synthesis of a single study.
- It does not establish long-term health outcomes. The authors specifically call for future trials to examine long-term effects.
- It does not identify an optimal protocol. Temperature ranged from 7°C to 15°C and duration from 30 seconds to 2 hours across included studies.
- It does not generalise across populations. The authors note a lack of diversity in study populations.
- It does not distinguish a chilled plunge system from an ice bath or a cold shower; all three were pooled.
Evidence strength
Systematic review with meta-analysis
A meta-analysis statistically pools results from multiple studies to produce a combined estimate, which is generally the strongest form of evidence short of a single very large trial.
Its strength depends entirely on what went into it. Here that was 11 randomised studies with a mean PEDro methodological quality score of 6.4 - seven rated moderate quality and four high. That is a respectable but small base, and the authors are explicit that the field is constrained by few randomised trials and limited population diversity.
Strengths and limitations
Strengths
- Most recent synthesis available, published 2025.
- Restricted to randomised trials in healthy adults, which matches the question a general buyer is asking.
- Large pooled sample at 3,177 participants.
- Formal quality appraisal using the PEDro scale, with scores reported.
- Pre-registered on PROSPERO, reducing scope for selective reporting.
- Assessed outcomes at multiple timepoints rather than a single post-exposure measurement, which is what revealed the time-dependency.
- Reports null results alongside positive ones.
Limitations
- Only 11 studies met inclusion criteria.
- Wide heterogeneity in temperature (7-15°C) and duration (30 seconds to 2 hours).
- Lack of diversity in study populations, acknowledged by the authors.
- Several outcomes rest on a small number of trials.
- Effects were time-dependent, and multiple timepoint comparisons increase the chance of a spurious positive.
- Immersion method varied (bath versus shower), and neither is a temperature-controlled circulating plunge.
- Sex distribution of participants not reported in the source.
Does this apply to the equipment IMPERVITA sells?
This is closer to a cold plunge purchase than most of the cold literature, but it is still not a study of chilled plunge systems.
Ten of the eleven studies used baths - which in practice means water chilled with ice to a target temperature, not a filtered system holding a setpoint continuously. The physiological exposure is comparable: cold water at 7-15°C for a defined period. What a plunge system changes is not the exposure but the logistics of repeating it.
That distinction matters for how you read the evidence. Nothing here suggests a chilled system produces different physiological results from an ice bath at the same temperature. What a chilled system offers is a repeatable, known temperature and sanitation that makes frequent use practical - and since several effects in this review relate to regular rather than single exposures, repeatability is the relevant benefit.
No published evidence distinguishes the health outcomes of one plunge brand from another.
Evidence in context
This review broadly agrees with the older exercise-recovery literature on direction while asking a different question. The 2012 Cochrane review found cold immersion reduced delayed-onset muscle soreness compared with passive recovery, and a 2018 meta-analysis of recovery techniques placed cold exposure among the more effective methods for inflammatory markers - in exercising populations.
It also sits alongside a genuine tension in the field. A 2015 randomised trial found cold immersion immediately after resistance training blunted long-term strength and hypertrophy adaptation, and a 2021 review concluded that chronic cryotherapy use during resistance training blunts the anabolic training effect. Those findings concern timing rather than whether cold immersion does anything.
A 2022 review of voluntary cold-water exposure describes the field as a continuing subject of debate, which remains a fair summary. Evidence quality has improved since 2012 but the number of high-quality randomised trials is still small.
Related research
- Cold-water immersion (cryotherapy) for preventing and treating muscle soreness after exercise The Cochrane review of cold immersion for muscle soreness - the benchmark for the exercise-recovery question rather than the general-wellbeing one.
- Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training The randomised trial showing blunted strength adaptation when cold immersion follows resistance training, which is the key timing caveat.
- Cold water immersion: kill or cure? The safety review covering the cold shock response and the circumstances in which cold water is genuinely dangerous.
- Health effects of voluntary exposure to cold water - a continuing subject of debate A review that deliberately presents the field as unsettled and examines the metabolic and immune claims critically.
- The cold truth: the role of cryotherapy in the treatment of injury and recovery from exercise Separates cryotherapy for acute injury from cryotherapy as a routine recovery habit.
- An evidence-based approach for choosing post-exercise recovery techniques to reduce markers of muscle damage, soreness, fatigue, and inflammation Places cold exposure alongside massage, compression and active recovery on shared outcome measures.
Practical buyer relevance
Three things follow from this review for someone comparing plunge systems.
First, be sceptical of anti-inflammatory marketing. In healthy adults this meta-analysis found an acute inflammatory increase. A seller who claims otherwise is not citing the current best evidence.
Second, the outcomes that did look favourable - stress at 12 hours, sleep quality, quality of life - relate to regular use. That makes the specifications governing whether you will keep using it the ones that matter: how quickly the system recovers temperature between sessions, how much maintenance the water needs, and whether it sits somewhere you will actually walk to. Those are the questions covered in the cold plunge buying guide.
Third, temperature is a genuine variable, not a marketing number. Studies here ran from 7°C to 15°C. A system that holds a setpoint reliably lets you keep a protocol consistent; a system that drifts several degrees through a hot afternoon does not. Ask for the maintained temperature at a stated ambient temperature, not the minimum the chiller can reach.
Safety context
Cold-water immersion carries genuine physiological risk. Sudden immersion triggers the cold shock response - an involuntary gasp, hyperventilation, and a sharp rise in cardiac load - which is the mechanism behind cold-water drowning and is documented in the review by Tipton and colleagues listed in this library.
People with cardiovascular disease, high blood pressure, a heart rhythm disorder, Raynaud phenomenon, or cold urticaria, and people who are pregnant, may require guidance from a qualified healthcare professional before using cold immersion. Never plunge alone, and never after drinking alcohol.
Full source record
- Title
- Effects of Cold-Water Immersion on Health and Wellbeing: A Systematic Review and Meta-Analysis
- Authors
- Cain T, Brinsley J, Bennett H, et al.
- Organization
- University of South Australia
- Publication
- PLOS ONE
- Year
- 2025
- Volume / issue / pages
- Volume 20, issue 1, article e0317615
- PMID
- 39879231
- PMCID
- PMC11778651
- Study type
- Systematic review with meta-analysis of randomised trials
- Sample size
- 11 studies, 3,177 participants
- Population
- Healthy adults aged 18 and over
- Topic
- Cold Therapy, Recovery, Sleep
- Document type
- Meta-analysis
- Technology context
- Cold-water immersion in baths and showers at 7-15°C - closest available evidence for chilled plunge systems
- Related equipment context
- Cold Plunge Systems
- Source last verified
- 19 August 2026
References
- Effects of cold-water immersion on health and wellbeing: a systematic review and meta-analysis
- Cold-water immersion (cryotherapy) for preventing and treating muscle soreness after exercise
- Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training
- Cold water immersion: kill or cure?
- Health effects of voluntary exposure to cold water - a continuing subject of debate
- The cold truth: the role of cryotherapy in the treatment of injury and recovery from exercise
- An evidence-based approach for choosing post-exercise recovery techniques to reduce markers of muscle damage, soreness, fatigue, and inflammation
Information provided by IMPERVITA is for educational and general wellness purposes and is not intended to replace professional medical advice, diagnosis, or treatment.
