"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&#039;m tired, it usually works very well.  "