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The Research

Adelaide researchers pooled the cold plunge evidence. Here is what held up.

Xavi Donobedian 1 min read

A University of South Australia review brought together 11 studies on cold water immersion. What worked, what did not, and what we still do not know.

Timber jetty into a calm sea at sunrise with a lone swimmer

Some of the most balanced cold water research of the past two years came from just down the road from our Somerton Park showroom.

The review

Researchers at the University of South Australia published a systematic review and meta-analysis in PLOS ONE in 2025. They pooled 11 studies with 3,177 healthy adults, using water at 15 °C or colder, by cold shower, ice bath or plunge.

What held up

  • Stress was lower 12 hours after immersion.
  • Sleep quality and quality of life improved.
  • One trial reported 29 per cent fewer sick days among people who took cold showers.

What did not, or not yet

  • Mood showed no significant change in the pooled data.
  • Inflammation rose immediately after immersion and an hour later. That is an acute stress response, not necessarily a bad thing, but it is not the calming story often told.
  • Immune markers did not change significantly in the short term.

The authors' caution

The evidence base has few randomised trials, small samples and limited diversity. The effects are time-dependent. They call for longer, better trials.

What we take from it

Cold water looks most useful as a stress and wellbeing practice, with some support for sleep. It is not a mood cure, and it is not a switch for inflammation.

That is a solid reason to own an ice bath. It is also a more honest one than most marketing offers.

  • Stay within the studied range: at or below 15 °C does not need to mean near freezing.
  • Short, regular sessions beat occasional heroics.
  • Pair it with the rest of your routine rather than using it as a fix.

Free: The Norge Longevity Guide. Heat, cold and light after 50, with the evidence and the safety rules in one place. Get the guide.

Sources

  1. Cain et al., Effects of cold-water immersion on health and wellbeing: a systematic review and meta-analysis, PLOS ONE, 2025
  2. University of South Australia via ScienceDaily

This article is general information, not medical advice. If you have a heart condition, low blood pressure or are pregnant, speak with your GP before using heat or cold.

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