Andrew Huberman· PhD
One to three minutes of cold water exposure will wake you up because of that adrenaline release and, and I want to highlight the and, it will serve to increase your core body temperature. That's right, your body and brain interact as a bit of a thermostat system where if you put something cold on the surface of your body, your brain, a little cluster of neurons in the so-called medial preoptic area, act as a thermostat and say, "Ah, the external of my body is cold and therefore I'm going to heat up my core body temperature." So it's a little bit paradoxical. People think, oh, if you get into cold water or an ice bath, your body temperature is going to drop. And indeed, that's true if you stay in for a while, but if you just get in for about one to three minutes, or under the cold shower for one to three minutes, your core body temperature will increase.