Cold water and wellbeing: what the trials show so far
A review gathered every randomized trial of cold water in healthy adults. Stress was lower half a day later, sleep and quality of life improved in single studies, and mood did not change.
Worth knowing: A review is a snapshot of its search date. Several findings rest on one trial each, so a single new study could change them.
The short version
This review pooled 11 randomized trials in which healthy adults sat in cold water or took a cold shower at 15°C or colder. Stress was lower 12 hours afterwards, though not at other times. Inflammation markers rose in the first hour, a normal stress response. Single trials reported better sleep, slightly better quality of life and fewer sick days. The one trial that measured mood found no change. Most trials were small, and one cold-shower trial supplied nearly all the participants.
Keep in mind
Few trials, most small, and 3,018 of the 3,177 people came from one cold-shower trial. Several findings rest on a single study.
What they found
Stress was lower 12 hours after cold water (standardized difference −1.00, 95% confidence interval −1.40 to −0.61). There was no difference immediately, at 1 hour, 24 hours or 48 hours.
Inflammation markers rose immediately (1.03) and at 1 hour (1.26), an acute stress response. Immune measures did not change in the first hour.
Single trials reported better sleep quality, slightly better quality of life and 29% less sickness absence among people taking cold showers. The one trial that measured mood, in 20 men after exercise, found no difference.
What this means for your practice
Cold water may help some people feel less stressed later in the day, and it does not appear to harm healthy adults in these trials. It is not an established mood lift.
This does not establish a cold-water routine to follow. Go in gradually and never swim alone in open water.
Methods and limitations
What the researchers did
The reviewers searched for randomized trials in healthy adults using a cold shower, ice bath or plunge at 15°C or colder for at least 30 seconds. Elite athletes were left out.
They looked at sleep, stress, fatigue, immunity, inflammation, mental wellbeing, mood, anxiety and concentration, and pooled studies where several measured the same thing.
Eleven trials qualified, with 3,177 participants. Ten used baths and one used showers, at 7°C to 15°C, for 30 seconds up to 2 hours.
How much can this tell us?
This is the most complete look so far at what cold water does for healthy people outside sport. Its main message is how little has been tested well.
Many findings come from a single trial. The pooled stress result appears at one time point only, which makes it fragile.
Most people in the review come from one Dutch cold-shower trial, also in this library. A plunge after a sauna, in company, is a different practice from most of what was tested.
What makes it useful
- Randomized trials only
- Healthy adults, not elite athletes
- Separates effects by time after the dip
What limits it
- Only 11 trials, most of them small
- One trial supplied nearly all participants
- Many outcomes rest on one study
Where this study fits
Where this study fits
We score claims, not single studies. This one is part of the evidence for:
Cold showers mean fewer sick days. Some support
Low certaintyMedium effectIllness and death
Cold water makes you feel better. Some support
Low certaintySmall effectHow you feel or perform
Read the original
Cain T, Brinsley J, Bennett H, Nelson M, Maher C, Singh B. Effects of cold-water immersion on health and wellbeing: A systematic review and meta-analysis. PLoS One. 2025;20(1):e0317615.
DOI 10.1371/journal.pone.0317615 · PubMed 39879231