Dr. Kevin Tracey

Your heart rate goes up.

Your blood pressure goes up.

And that's the opposite, allegedly, of a parasympathetic arrest and digest response.

But what happens if you stay in the cold water and you cold adapt?

And here, Eric, it's very hard to find well-controlled...

Clinical studies.

I found a few, and they're in the book.

But it's very hard.

Usually it's military-type soldiers in Iceland or something or in the Baltic states getting sprayed with water in a cold room and dressed in a bathing suit.

And then they give their blood.

So there's some data like this.

If you cold adapt to some point for some period of time, you will actually feel your heart rate slow down, at which point you can say, my vagus response is exceeding my fight or flight response.

They're both still active, by the way.

But let's just say that you've tipped from primarily sympathetic to primarily parasympathetic.

So, okay, now you've stimulated your vagus nerve, but you've done a million other things to your nervous system

Two, you haven't put a device on your neck targeting a few hundred fibers to turn off inflammation.

Now, do the fibers that made your blood pressure go up first and then down and your heart rate go up first and then go down, are those the same fibers that go to your spleen and control inflammation?

I don't think so.

Does the whole thing act as an on-block effect?

everything at once response?