Cold exposure and stress hormones over 12 weeks
Twenty women did regular winter swimming or whole-body cryotherapy for 12 weeks. One stress-hormone response stayed strong throughout; another faded.
The short version
Twenty healthy women did either winter swimming (a very brief dip in near-freezing water) or whole-body cryotherapy three times a week for 12 weeks. Each session still raised their noradrenaline two- to three-fold, with no sign of that response fading over the three months. Their ACTH and cortisol response, by contrast, became smaller over the same weeks, suggesting the body’s stress-axis response settled down with repetition. Markers of inflammation did not change. The study included only women, was small, and had no group that skipped cold exposure altogether, so it cannot show what would have happened without it.
Keep in mind
Small, women-only, and with no group that skipped cold exposure, so it cannot show what would have happened without it.
What they found
Noradrenaline rose two- to three-fold after cold exposure throughout the 12 weeks, in both the winter-swimming and cryotherapy groups, with no sign that this response weakened with repetition.
ACTH and cortisol, two markers of the body’s stress-axis response, were lower by weeks 4 through 12 than in week 1, suggesting this particular response settled down with repeated exposure. Adrenaline and the inflammatory markers measured (IL-1β, IL-6, TNF-α) did not change.
What this means for your practice
This tells us something about how the body’s stress hormones respond to repeated cold exposure, not what cold exposure does for health or mood over time.
This does not establish a cold-exposure routine to follow. In KUUME, cold water is always your own choice, never a default.
Methods and limitations
What the researchers did
Twenty healthy Finnish women took part in either regular winter swimming (about 20 seconds in 0-2°C water) or whole-body cryotherapy (about 2 minutes at -110°C), three times a week for 12 weeks. Researchers drew blood at intervals to track hormones and inflammatory markers.
This tests whether the body’s response to cold changes with repetition, not just what happens after a single exposure.
There was no group that avoided cold exposure altogether, so the study cannot say what would have happened to these markers over 12 weeks without any cold exposure.
How much can this tell us?
This was a repeated-measures study in a small, healthy, female-only group, with no comparison group that skipped cold exposure. It cannot tell us what would happen in men, in people with health conditions, or without any cold exposure at all.
A hormone response that persists or fades over 12 weeks is a physiological finding, not by itself a noticeable or lasting health benefit.
What makes it useful
- Tracked the same people repeatedly over 12 weeks, not just once
- Compared two different cold methods, with similar hormone results
- Measured inflammatory markers as well as hormones
What limits it
- Small (20 people) and women only
- No group that skipped cold exposure altogether
- A hormone change is not the same as a measured health benefit
Where this study fits
Where this study fits
We score claims, not single studies. This one is part of the evidence for:
Cold water triggers a surge of noradrenaline and dopamine. Well supported
Moderate certaintyLarge effectBody signals
Read the original
Leppäluoto J, Westerlund T, Huttunen P, Oksa J, Smolander J, Dugué B, Mikkelsson M. Effects of long-term whole-body cold exposures on plasma concentrations of ACTH, beta-endorphin, cortisol, catecholamines and cytokines in healthy females. Scand J Clin Lab Invest. 2008;68(2):145-153.
DOI 10.1080/00365510701516350 · PubMed 18382932