Cold plunges do offer real stress relief, but the effects appear to transient rather than transformative. A major 2025 review found little evidence for lasting improvements in mood, sleep or quality of life. It examined cold exposure on its own, not contrast therapy.
Why cold plunges became a stress solution
Cold plunges have come to represent a certain kind of modern resilience. They’re often framed as a way to train the mind, sharpen focus and build mental toughness through discomfort. The logic is appealing: do something hard, emerge calmer on the other side.
For many people, that experience feels genuine. A cold plunge can cut through mental noise and create a strong sense of reset. But feeling better in the moment is not the same as delivering lasting change. As cold exposure becomes more widely used for stress relief, it’s worth asking what the evidence actually shows.
In 2025, researchers at the University of South Australia set out to examine exactly that.
What this study set out to examine
The University of South Australia published a systematic review and meta-analysis exploring the effects of cold-water immersion on mental and physical health outcomes. Rather than relying on individual trials, the researchers analysed results across multiple studies to identify consistent patterns.
Crucially, the review looked at cold exposure in isolation. This included ice baths, cold plunges and cold showers. Some studies used cold-only interval protocols (for example, repeated short immersions separated by time out of the water), but the review did not assess contrast therapy involving heat. Sauna-to-ice-bath routines, hot tub and cold plunge cycles, and other hot-and-cold approaches fall outside the scope of this research.
The findings therefore apply specifically to cold-water immersion on its own.
Stress reduction: real, measurable and short-lived
When it comes to stress, the signal was clear, but modest.
Across the studies reviewed, cold-water immersion was associated with a reduction in perceived stress at around 12 hours post-exposure. That effect was not seen immediately after immersion, nor did it reliably persist at later time points. In other words, stress levels returned to baseline.
Harvard Health’s summary of the same meta-analysis helps explain why. Cold exposure activates the body’s fight-or-flight response, increasing heart rate, breathing and stress hormones. Once the exposure ends, the nervous system settles. That contrast can feel calming, but it does not appear to retrain the stress response over time.
Put simply, cold plunges can take the edge off stress for part of a day. They do not appear to reduce underlying stress levels in a lasting way.
Mood, sleep and quality of life: weaker signals
Beyond stress, the evidence was less convincing.
The review found little consistent support for lasting improvements in mood or mental health. While individual studies occasionally reported benefits, those effects did not reliably hold up when results were pooled.
Sleep outcomes were mixed. Some improvement was observed, but only in men, and not consistently enough to suggest a dependable benefit. Measures of overall quality of life showed small early gains, but these faded after a few months of continued cold-water immersion.
Overall, the findings suggest cold plunges may influence how people feel shortly after use, without meaningfully shifting longer-term wellbeing.
A note on physical responses (and why they don’t change the stress picture)
Because the review examined both mental and physical outcomes, it’s worth briefly addressing the physical findings in context.
The researchers observed a temporary increase in inflammatory markers immediately after cold-water immersion, and again shortly afterwards. This reflects an acute stress response rather than recovery. There was no convincing evidence of sustained reductions in baseline inflammation or improvements in immune function.
This does not mean cold therapy has no physical applications. Other research suggests cold exposure can reduce perceived muscle soreness after intense exercise. However, those effects are situational and short-lived, and they do not translate into improved stress resilience or long-term health.
In that sense, the physical responses help explain why stress relief occurs briefly, but not why it would persist.
Why contrast therapy sits outside this discussion
It’s important to be clear about what this study does not cover.
Contrast therapy, where cold exposure is alternated with heat, works through different physiological mechanisms. Cold stimulates the stress response, while heat tends to promote relaxation and parasympathetic nervous system activity. Alternating between the two can feel very different from cold exposure alone.
Because the University of South Australia review did not include hot-and-cold contrast protocols, its findings should not be used to judge those routines either positively or negatively. That remains a separate question, and one that requires its own high-quality evidence.
What this study actually tells us
The key takeaway from the University of South Australia review is that cold plunges do offer genuine benefits, but those benefits are more limited than popular culture would have us believe.
- Cold plunges can reduce stress, but the effect is short-term
- There is little evidence for lasting improvements in mood, sleep or quality of life
- Physical responses appear to be acute rather than cumulative
- The findings apply to cold exposure alone, not contrast therapy
Cold plunges may have a role as an occasional stress interrupter, in much the same way that short-term symptom relief can help someone cope, but they are not a substitute for addressing the underlying causes of stress.
Keeping cold and stress in perspective
Cold plunges can feel powerful, and for some people that brief sense of calm is genuinely worthwhile. The science suggests they are best understood for what they are: a short-term modifier of stress, not a foundational solution.
At Hot Tubs Oxfordshire, we believe the most effective wellness choices come from clarity rather than extremes. Knowing where cold exposure helps, where it doesn’t, and where the evidence stops allows people to make more informed, sustainable decisions about managing stress in everyday life.
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