this book. I read portions of it at Amazon and boy does it seem dead on.
“Just being around people can be overstimulating to introverts. Their energy is drained in crowds, classes, or any noisy and invasive environment. They may like people very much, but after talking to anyone, they usually begin to feel the need to move away, take a break and get some air. When overstimulated, the introvert’s mind can shut down, saying, no more input, please. It goes dark.”
This totally explains my need for a forced downtime after any socially involved event. OMG. Did I mention I had to have it?