Sauna use or heat stress can lead to lasting positive effects on mood and anxiety, potentially mediated by the dynorphin pathway.

“But over time that binding of dynorphine into the CAPA receptor leads to downstream changes in the way that the feel good endorphins, things like endorphin binding to the mu opioid receptor, and there are still other feel good endorphins, so to speak. That system becomes much more efficient, such that people feel an elevation in their baseline level of mood, and when a good or happy event comes along, they feel a heightened level of happiness or joy or awe or improved mood in response to that.”

“And in terms of the mental health benefits, it seems that getting a little bit uncomfortable in that heat environment, sauna or otherwise, provided it's safe, is going to be the best way to access those mental health effects by way of increasing dinorphine, which as you recall, will then increase the ability of endorphin to have its positive effects on mood after you get out of the sauna or other deliberate heat exposure.”

“But over time, that binding of dinorphine to the cappa receptor leads to downstream changes in the way that the feel-good endorphins, things like endorphin binding to the muopioid receptor, and there are still other feel-good endorphins, so to speak. That system becomes much much more efficient such that people feel an elevation in their baseline level of mood. And when a good or happy event comes along, they feel a heightened level of happiness or joy or awe or improved mood in response to that.”

“And I started to notice...so when I was in graduate school, I was very stressed out, lots of pressure, failed experiments, and exams. And so I started using the sauna a lot before I'd go into the lab and I noticed that there was a very profound effect on my brain because I started to be able to handle stress better. My anxiety was lower. I felt good, and these were lasting effects. I felt good days later. And so I started reading about what's going on here. I started reading about heat stress, and I came across the dynorphin pathway which is an endogenous opioid that we make in our brains, sort of the counter to endorphin because it sort of makes you feel dysphoric rather than euphoric. And then I started reading about how dynorphin actually is a part of the...both endorphin and dynorphin are part of the thermoregulatory pathway. So dynorphin actually cools the body down. And when your body heats up, you increase dynorphin to cool it down. It's sort of a response mechanism. So when you're sitting in a hot sauna or when you're working out really vigorously and you feel that sort of uncomfortable heat where you're like, "Oh, I want to stop. I feel..." I think that's probably dynorphin. So dynorphin binds to the kappa-opioid receptor which then sensitizes the mu-opioid receptors. So now, I was thinking, well, maybe some of these lasting effects from the sauna were mediated through that.”