>Extroverts find socializing energizing. And can find alone time draining.

This sounds insane to me. I'm an introversion solipsist.

Socialization is inherently more demanding. Whole parts of the brain must light up -- reading faces and tone and filtering thoughts and modulating your speech and delivery and listening to others' speech. By physics alone, in the same way that a computer processing some data necessarily consumes more power than a computer doing nothing, socialization must burn more brain calories than not socializing.

After I've socialized a lot, I'm dead tired (and maybe more stressed).