Health Haven

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.