insomnia
"I have been taking ambien or zolphidem for almost 15 years. I had horrible insomnia where I couldn't sleep sometimes at all during the night. The insomnia went on for about 2 years before I tried ambien. it worked immediately.  I don't take it every night and when I do I break off a third of the pill. The only side effect is sometimes grogginess in the morning. I worry about a little memory loss. I was told it disrupts your REM sleep which can affect memory. Trying to get off completely but don't want to go through that horrible insomnia again."