Daily sauna use does produce real acute physiological signals (heart rate, heat-shock proteins, relaxation, and a measured BDNF increase) — but the claim that it "literally grows new brain cells" goes well beyond what those same studies show.

noli's read

The day-by-day progression (day 1: heat-shock proteins; day 5: cardiovascular efficiency; day 10: cortisol and endorphins; day 14: BDNF and "new brain cells") stacks real acute signals into a slightly too-tidy narrative. Heat-shock proteins are well documented from the first sessions onward. Improved cardiovascular efficiency with repeated sauna use is plausible and consistent with the heat-adaptation literature. The relaxation and mood lift after a session are documented by a Japanese study on the so-called "totonou" state (EEG measurements, 2023). BDNF does rise acutely after heat exposure — several studies confirm this (hot water immersion, repeated sauna over 7-10 weeks in both young and older subjects). But the jump from "higher BDNF" to "literally growing new brain cells" is a stretch: BDNF supports synaptic plasticity and neuron survival, it isn't proof of measurable human neurogenesis — a topic that remains debated in adults to begin with. This is the video's most clearly overstated point, grafted onto otherwise real mechanisms.

the sources

1. 1Laukkanen T, Khan H, Zaccardi F, Laukkanen JA 2015
2. 2Laukkanen T, Kunutsor SK, Zaccardi F, et al. 2018