This was a very interesting article, given that I just experienced something similar.

Flight from SFO -> IAD last week. As soon as we took off, they asked for a doctor. He spent 2 hours treating the patient before they started drink service, and continued until we landed. We were all quite worried about the person, but found out at the end of the flight that they had overdosed on NyQuil. That made the whole ordeal fairly frustrating.