Two hours of sauna a day for a week sent growth hormone up 16-fold
The 16-fold growth hormone claim comes from a 1986 study in Acta Physiologica Scandinavica. Researchers put ten Finnish men through fourteen hours of sauna in seven days.
The paper
Endocrine effects of repeated sauna bathing
Leppäluoto J, Huttunen P, Hirvonen J, Väänänen A, et al.. Acta Physiologica Scandinavica, 1986;128(3):467-470.
See the study at a glance
- Design
- Single-group study of repeated saunas
- People
- 10 men and 7 women
- Who they were
- The participants were healthy Finnish adults. The women took part only in the prolactin measurements.
- What they did
- Each session was an hour in an 80°C Finnish sauna, twice a day for seven days. Blood was drawn beforehand and on days 1, 3 and 7.
- How long
- One week
These numbers came out of it
16×
The men's growth hormone rose this much over their own starting levels.
Day 3
By the authors' account, this is when the growth hormone response began to fade.
2.3×
Prolactin rose this much in the men and more than fourfold in the women.
5 of 7
Five of the seven women missed a period after the experiment.
The researchers did this
Ten healthy men sat in an 80°C sauna for an hour, twice a day, for seven days in a row. Blood samples taken before and during the week tracked a panel of hormones.Source 1 · Clinical trialEndocrine effects of repeated sauna bathingLeppäluoto J, Huttunen P, Hirvonen J, et al.. Acta Physiologica Scandinavica, 1986.Read the paper ↗PubMed ↗
In the men, growth hormone rose 16-fold and prolactin 2.3-fold. The growth hormone response faded after the third day, while prolactin stayed high to the end. Thyroid hormones and testosterone held steady, and cortisol dipped slightly.
The authors suggested that the dehydration from so much sweating may be behind the rise in growth hormone and prolactin. Among the women, five of the seven missed a period after the experiment.
The study can't tell you these things
- There was no comparison group of people who skipped the sauna, so every change is measured against the same people a few days earlier.
- Fourteen hours of sauna in a week is far more than anyone takes at home.
- Hormones were all the study measured, so it can't tell you anything about muscle or health.
- The abstract doesn't say which day growth hormone peaked.
People quote it like this
Podcasts and wellness sites cite this paper for the idea that saunas raise growth hormone 16-fold. Most leave out the two hours a day it took and the fade after day three. An ordinary 15-minute session produced a far smaller rise, and older men showed none.Source 2 · Clinical trialHeat Exposure Elevates Plasma Immunoreactive Growth Hormone-Releasing Hormone Levels in Man*Leppäluoto J, Tapanainen P, Knip M. The Journal of Clinical Endocrinology & Metabolism, 1987.Read the paper ↗PubMed ↗
We cited these sources
- 01Leppäluoto J, Huttunen P, Hirvonen J, Väänänen A, Tuominen M, Vuori J. Endocrine effects of repeated sauna bathing. Acta Physiologica Scandinavica. 1986;128(3):467-470. doi:10.1111/j.1748-1716.1986.tb08000.x PMID 3788622
- 02Leppäluoto J, Tapanainen P, Knip M. Heat Exposure Elevates Plasma Immunoreactive Growth Hormone-Releasing Hormone Levels in Man*. The Journal of Clinical Endocrinology & Metabolism. 1987;65(5):1035-1038. doi:10.1210/jcem-65-5-1035 PMID 3117831