hmm, that's an interesting perspective. see my comment here:
https://news.ycombinator.com/item?id=36795067
i can definitely see that the comfort level is a factor. however, it can take a long time before i get comfortable with someone. i have no idea how much, but a few hours at a party are almost never enough, unless we hit the right topic. so yeah, after those conversations i was bouncing off the walls too.
likewise i have given presentations on various topics in front of dozens or hundreds of people. my comfort level depended on how well prepared i was, and how the audience reacted. during the speech part anxiety is higher because i get little to no feedback, but then the Q&A can turn things around if people have lots of questions that show their interest in the topic.
oh, and when i am drained, i can't go to sleep. i have to do something interesting for myself for at least an hour or more in order to divert my thoughts away from the draining experience.