It wasn't like he was a stable guy taking it for insomnia. He had long history of personality disorder, including multiple personalities, and drug abuse.

"This, incidentally, is what Bergwall says was his daily intake, with extra top-ups when requested: six 5 mg. Valium, four 1 mg. Xanax, one 10 mg. prefill Valium, 1.5 mg. Halcion, two Rohypnol, six Treo comp, six Panocod."

http://www.gq.com/story/thomas-quick-serial-killer-august-20...