Skip to content
Sauna Hype

Whole-body heating raised blood BDNF in ten men

In this 2021 PLOS ONE study, ten men spent 90 minutes in a water-perfused suit under three conditions. Researchers measured brain-derived neurotrophic factor (BDNF), a protein that helps nerve cells grow and survive, in their blood.

The paper

Serum and plasma brain-derived neurotrophic factor concentration are elevated by systemic but not local passive heating

Ogawa T, Hoekstra SP, Kamijo YI, Goosey-Tolfrey VL, et al.. PLOS ONE, 2021;16(12):e0260775.

Read the paper ↗PubMed 34882699 ↗Free full text ↗

See the study at a glance

Design
Crossover study with three conditions
People
10 men
Who they were
Recreationally active men.
What they did
Ninety minutes on three occasions in a suit that pumps water through tubes against the skin. The suit heated the whole body on one visit. On another it heated the legs and cooled the upper body, and the third visit was a control.
How long
Three separate sessions

These numbers came out of it

19.1 → 25.9

Serum BDNF rose from 19.1 to 25.9 ng/mL with whole-body heating.

2.74 → 4.58

Plasma BDNF went from 2.74 to 4.58 ng/mL with whole-body heating.

No rise

Heating only the legs didn't raise BDNF.

Unchanged

Each platelet carried the same amount of BDNF as before, and platelet counts rose along with BDNF.

The researchers did this

Ten recreationally active men spent 90 minutes in a water-perfused suit on three occasions.Source 1 · Crossover trialSerum and plasma brain-derived neurotrophic factor concentration are elevated by systemic but not local passive heatingOgawa T, Hoekstra SP, Kamijo YI, et al.. PLOS ONE, 2021.Read the paper ↗PubMed ↗ One session heated the whole body. Another heated the legs while cooling the upper body, and the third served as a control.

Whole-body heating raised serum BDNF from 19.1 to 25.9 ng/mL. Plasma BDNF climbed from 2.74 to 4.58 ng/mL. When only the legs were heated, neither measure rose.

Platelet counts rose along with BDNF after whole-body heating, and the amount of BDNF per platelet did not change.

A hot-water study found a similar short rise. In eight men, 20 minutes in 42°C water raised serum BDNF at the end of the soak and 15 minutes later. Levels were back to baseline by 30 minutes.Source 2 · Crossover trialHead-out immersion in hot water increases serum BDNF in healthy malesKojima D, Nakamura T, Banno M, et al.. International Journal of Hyperthermia, 2018.Read the paper ↗PubMed ↗

The study can't tell you these things

  • The study had ten recreationally active men and no women.
  • The heat came from a water-perfused suit worn for 90 minutes. We couldn't find any study that measured BDNF after a sauna.
  • BDNF was measured in blood, and the study didn't test the brain or thinking.
  • How long the rise lasted after the heat stopped isn't in the abstract.

We cited these sources

  1. 01Ogawa T, Hoekstra SP, Kamijo YI, Goosey-Tolfrey VL, Walsh JJ, Tajima F. F, et al.. Serum and plasma brain-derived neurotrophic factor concentration are elevated by systemic but not local passive heating. PLOS ONE. 2021;16(12):e0260775. doi:10.1371/journal.pone.0260775 PMID 34882699
  2. 02Kojima D, Nakamura T, Banno M, Umemoto Y, Kinoshita T, Ishida Y, et al.. Head-out immersion in hot water increases serum BDNF in healthy males. International Journal of Hyperthermia. 2018;34(6):834-839. doi:10.1080/02656736.2017.1394502 PMID 29157042