insomnia
"I am a registered nurse and I have found that different people react differenly to the same medication.  That goes for all types of medications.  As for me, I have been taking this for about a year.  It has been a life-saver for me because I have always had trouble in trying to sleep through the night.  However, most nights it works within 30 mins and I sleep pretty well through the night.  Occasionally, it does not seem to be working.  I think it has to do with how tired I am, if I have drank coffee, drank a coke, or eaten chocolate late in the day.  If I'm tired, it usually works very well.  "