the big thing is how you feel after. That’s an altered state, a preferable state, especially if you can do a complete immersion vs shower. That supposedly activates both the PNS and SNS. But beyond that wonderfully energized sense of well-being that endures for an hour or so after the treatment, you also have extended levels of dopamine.
Cold water immersion provides a 2.5x incresae in long-duration dopamine, up to 3 – 4 hours. In that sense, there is nothing else that compares to cold water in terms of creating sustained increases in dopamine.
Some say your circulation benefits.
There’s also a self-discipline you will have to develop in order to routinely immerse yourself in cold water. No matter how many times you do it, the Id will try to talk you out of it. That’s because it’s built on the pleasure principle. It only wants pleasure. And stepping into cold water is not pleasurable.