Justin Bieber is recovering from concussion after he knocked himself out during a show in Paris.The Boyfriend singer was performing in the capital on Thursday evening when he walked into a glass wall backstage and lost consciousness."So basically... I'm in Paris and I'm like, performing on the tallest building in Paris," Bieber told TMZ . "There's a glass wall behind me, but there's a railing behind the glass, and so, I went to reach for the railing and I hit my head on the glass."It really hurt and I felt a little light-headed, but my adrenalin, I feel, pushed me through it and I performed my last song. After that, I went off stage and I immediately felt really weak. I was walking down the stairs and I passed out for like, 15 seconds... I feel good, I have a little bit of a headache, but I feel fine. I mean, you've got to laugh at yourself sometimes."