The feeling you get the day after you see a really fantastic concert.
1. The desire to relive the concert,
2. Thoughts similar to "they the band
were right there!" or "i'm never going to see them again!"
3. Emotional pain when listening to the band's music.
Post concert depression can last up to a week, depending on the awesomeness of the concert, and, even after a long time, listening to the band's music may cause a relapse.
I saw (insert fantastic band here) last night and now i've got post concert depression!