People who ended showers with cold water missed fewer days of work
By self-report, there were 29% fewer days absent. No difference was observed on days participants felt ill.
The key idea
Fewer self-reported days absent did not mean fewer sick days: no clear difference appeared there.
The study, in plain language
More than 3,000 employed adults ages 18 to 65 were randomized to four groups: shower as usual or end with 30, 60, or 90 seconds of cold water. The assigned phase lasted one month, after which they could continue on their own for two more. Everything was measured with online surveys.
When the three cold-water groups were combined, the analysis estimated 29% fewer days of work absence than in the comparison group. There was no clear difference in days participants felt ill, and the three durations did not differ from each other. Participants reported everything themselves, knew which group they were in, and about 20% were lost to follow-up. The trial did not measure immune defenses or show that there were fewer infections.
What they found
- Those who ended their shower with cold water reported 29% fewer days of work absence than the comparison group.
- There was no robust difference between groups in the number of days participants felt ill.
- The three cold-water durations, from 30 to 90 seconds, did not differ in work absence.
How they studied it
Researchers randomized 3,018 employed adults ages 18 to 65 into four groups: usual shower or a cold finish of 30, 60, or 90 seconds. The assigned phase lasted 30 days, with 60 more days of optional continuation. Absence and sick days were measured by participants’ own survey responses.
What the study cannot show
- Participants reported outcomes and adherence themselves, there was no blinding, and about 19.6% were lost to follow-up.
- The trial measured self-reported sick and absence days, not immunity or confirmed infections.
Something to think about
When you hear that a habit improves health, what exactly was measured: symptom days or days off work? They tell different stories.
The original study
The Effect of Cold Showering on Health and Work: A Randomized Controlled Trial
Source under CC BY 4.0. English adaptation and explanation by PaperFlow, with AI assistance. The text has been reorganized for a general audience; it is not the complete paper and does not imply endorsement by its authors.
One study alone does not represent a field's consensus. Educational content does not replace professional advice. Report a possible error.
