insomnia
"Started taking Ambien 5 years ago while I was in nursing school. I would sometimes only get 45 minutes of sleep without it. With it I could easily sleep 8  hours. It worked amazingly well. Now, 5 years later, it seems I have built up quite the tolerance and sometimes need to take 2 just to make me half sleepy. Another problem is my doctor does not like to give me refills as this medicine is meant for short term use. He does refill it, but only after a long lecture every month."