Cold Plunge Benefits: Less Stress, Fewer Sick Days, Weaker Gains

Cold plunges are everywhere. Ice baths in gyms, tubs in back gardens, cold showers promoted as a daily reset.

The claims are big: less stress, better sleep, stronger immunity, faster recovery.

So what are the real cold plunge benefits? The research has caught up a little with the hype.

Some benefits look real, others are unproven, and there’s one surprising downside for anyone trying to build muscle.

What are the real cold plunge benefits?

The honest answer: some short-term effects on stress, recovery and possibly wellbeing. But the evidence is thinner than the marketing suggests.

The best overview is a 2025 systematic review and meta-analysis in PLOS One. Researchers at the University of South Australia gathered randomised trials of cold-water immersion in healthy adults.

They included cold showers, ice baths and plunges, in water of 15°C or colder, for at least 30 seconds.

The authors noted that cold plunges have grown hugely popular, with “largely unsupported claims” in the media. Their aim was to test those claims against the trials.

What the review found

Stress: lower, but only later

There was no clear change in stress immediately after a cold plunge, or one hour later. But 12 hours later, stress was significantly lower.

By 24 and 48 hours, the effect had gone again. So the benefit seems real but short-lived.

Inflammation: briefly up, not down

Many people plunge to reduce inflammation. In the short term, the review found the opposite.

Inflammation markers rose significantly immediately after the cold, and stayed raised an hour later. The authors describe this as an acute inflammatory response.

They note an earlier review found inflammation fell 24 hours after immersion. So timing matters, and the picture is mixed.

Sleep, mood and quality of life

One small trial in men found better sleep quality after cold immersion following heat training. The same trial found no difference in mood.

The largest study found slightly higher quality of life scores among people taking cold showers. Its own authors judged the gain too small to matter clinically.

The cold-shower trial: fewer sick days

What it tested

The biggest single study was a 2016 randomised trial in the Netherlands, published in PLOS One. It recruited 3,018 adults aged 18 to 65 who didn’t usually take cold showers.

Some were randomly assigned to a control group. The rest ended their usual hot shower with 30, 60 or 90 seconds of cold water, every day for 30 days.

What it found

People in the cold-shower groups took 29% fewer sick days off work than the control group.

But the number of days they actually felt ill didn’t change. The authors suggest the showers may have made symptoms milder, rather than shorter.

The length of the cold shower didn’t seem to matter. No serious side effects were linked to the showers, and 79% of people in the cold-shower groups stuck with it for the full 30 days.

Exercise mattered more

Regular physical activity on its own cut sick days by 35%. The authors estimate that cold showers plus regular exercise together would cut them by 54%.

Most people found the cold uncomfortable. Yet 64% carried on with cold showers after the study ended.

The most common benefit people reported was feeling more energetic. Some compared it with the effect of caffeine.

The twist for gym-goers

Recovery: some help

Cold plunges have long been used by athletes to recover. A September 2026 umbrella review in Sports Medicine – Open pulled together 15 meta-analyses covering 161 studies.

Cold-water immersion after exercise reduced muscle soreness for up to 96 hours. It also helped some measures of power and jump performance recover over the next day or two.

Strength: a real downside

But regular cold plunges after resistance training came with a cost. The review found they “impaired strength and hypertrophic gains”, meaning muscle growth.

The authors recommend using cold plunges strategically, rather than “routine application after all exercise sessions”.

They also flagged the evidence quality as low to very low. So even the recovery benefits are uncertain.

The risks of cold plunges

The cold shock response

Getting into very cold water triggers a sudden stress response. The 2025 review describes rapid rises in stress hormones and blood pressure within minutes of immersion.

That’s part of what may later lower stress. But it’s also why caution matters, especially for anyone with heart problems.

What the trials don’t tell us

The trials mostly included healthy adults, and most included only men. The cold-shower trial excluded people with serious health problems.

The 2025 review’s authors say future studies should closely examine safety. So the trials say little about risks for older people or those with medical conditions.

What earlier research found

The main review

The 2025 PLOS One review is the first to look broadly at cold-water immersion in the general public, rather than in athletes. Its authors conclude there is “currently limited high-quality evidence” for the general population.

The cold-shower trial

The 2016 cold-shower trial remains the largest single study. Its findings on sick days rested on self-reports, which the review notes could introduce bias.

Athletes and recovery

The 2026 umbrella review is the strongest summary for athletes. It found recovery benefits for soreness, but downsides for strength and muscle growth with routine use.

How it fits together

Cold plunges seem to do something. But the effects are specific and short-lived, and they depend on timing and how often you plunge.

How much should you trust this?

Early. There are real effects in randomised trials, but most studies are small, short and in narrow groups.

What makes it convincing

• The 2025 review included only randomised trials.
• The cold-shower trial was large, with over 3,000 participants.
• The 2026 umbrella review pooled 15 meta-analyses for athletes.

What makes me cautious

• Most trials were small, and most included only men.
• The sick-day finding relied on self-reports.
• Effects on stress appeared at one time point only.
• Evidence quality in the athlete review was low to very low.
• Water temperatures and times varied widely, so there’s no agreed “dose”.

What this means for you

• A short cold shower is a low-risk way to try it. The big trial used 30 to 90 seconds at the end of a shower.
• Don’t expect big health changes. The benefits found so far are modest and short-lived.
• If you lift weights, skip the ice bath right after. Regular use may blunt strength and muscle gains.
• Use it for soreness when it matters. It may help you recover for the next day’s training or event.
• Talk to a doctor first if you have a heart condition or other health problems, as the trials mostly studied healthy people.

In this short Wall Street Journal video, you can see the science behind cold plunges explained:

What we still don’t know

1. What’s the right dose? Temperature, time and frequency haven’t been worked out.
2. Are there long-term benefits? Most trials looked at short-term effects.
3. Does it help women in the same way? Almost all trials apart from the shower study included only men.
4. Is it safe for older people? Trials mostly studied healthy, younger adults.
5. How does it affect mood? Only one small trial has looked at this.

My take: a useful shock, not a cure-all

What I like about the research is that it tests a trend that’s mostly been driven by influencers. And some effects hold up.

I’m less convinced by the grand claims about immunity and inflammation. The evidence points in different directions, depending on timing.

If you enjoy a cold plunge, there’s no strong reason to stop. Just keep it short, avoid it straight after strength training, and don’t expect it to transform your health.