panic disorde
"I take alprazolam for panic attacks, which can hit at any time and be severe within just a minute or so.  I can take a half of one of these when I feel a panic attack coming on, and it usually stops it.  If it gets to a full-blown attack, then I can take a whole one and it will knock it out.  The only problem is that it does make me sleepy, which is much better than the panic attack."