I often find interaction tiring. The one exception for me is highly intellectually stimulating conversation.

I've noticed that my I/E orientation differs based on who I am around. Around good friends and generally intelligent people, I am more E. Around people I'm less familiar with, or people I assume I will not be interested in, I am much more I. If I've done a lot of socializing in the last few days, I am more likely to be I.