This is NPR's life kit. I'm Elise Hugh.

Dopamine. You've probably heard of it.

Dopamine is a chemical that we make in our brain,

and it's essential for the experience of reward, pleasure, and motivation.

That's Dr. Anna Lemke. She's a psychiatrist and on faculty at the Stanford University School of Medicine,

where she runs the Addiction Center.

I occupy the classic three-legged stool of academic medicine, which is I see patients,

I teach, and I do research.

You forgot to mention you're also an author.

Oh, yes, and I always forget that, by the way. I always forget that.

Dr. Lemke wrote a book called Dopamine Nation,

finding balance in the age of indulgence.

In it, she helps us better understand pleasure, feeling good.

But as it turns out, pleasure needs its counterweight, pain.

One of the most interesting findings in neuroscience in the past 75 years

is that pleasure and pain are co-located in the brain.

That means that the same parts of the brain that process pleasure also process pain,

and they work like opposite sides of a balance.

If you imagine that in your brain there's a teeter-totter, like in a kid's playground,

and when it's at rest, it's level with the ground.

When we experience pleasure, tips one way, when you experience pain, it tips the other.

But one of the overarching rules governing this balance is that it wants to remain level.

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