Dr. Matt Walker

And one of the fascinating things that we didn't quite mention in the episode where we described what is sleep, and we described the different stages, including REM, and we spoke about the brain changes.

Something utterly unique happens during REM sleep.

Levels of a brain chemical called noradrenaline are completely shut off.

It is the only time during the 24-hour period when you see the complete cessation of noradrenaline in the brain.

And of course, noradrenaline is associated with many different functions.

You've elegantly described them.

One of the functions is that it's associated with emotional responsivity and the focus and that sort of strong sort of emotional energy.

And people will know we speak about, it has two names, noradrenaline or norepinephrine, same thing, US, UK.

But people, of course, are familiar with the sister chemical in the body called adrenaline.

upstairs in the brain, we can think about noradrenaline.

And during REM sleep, noradrenaline is completely shut off.

This stress-associated neurochemical, it's not only associated with stress, but it's associated with lots of things, but stress included.

No, it's not.

It seems to be specifically within the brain that there is this blockade of noradrenaline and serotonin goes down too.

Whereas another chemical called acetylcholine, which is another neurotransmitter, that ramps up in the brain.

However, if you look at other parts of the brain, the memory-related centers of the brain, such as the hippocampus that we've spoken about before, and the amygdala that I just mentioned too, those are very active during REM sleep.

So we laid out this biological model that is almost beautiful.

That REM sleep is this perfect condition for emotional overnight therapy, where you can reactivate and sort of experience and reprocess those emotional memories.

But you're doing it in a neurochemically, quote unquote, safe environment that allows you to strip away the emotion from the memory.

Exactly.