5mg of melatonin may not be enough, especially if it's used irregularly. 10mg usually works for me. If you decide to use melatonin remember that it only brings on the initial drowsiness. It does not keep you asleep. As such, you need to be cognizant of when it starts acting and be ready to let the drowsiness to envelope you. If you fight it for whatever reason (i.e just want to finish out the paragraph of the book you carry with you on layovers), you just missed your opportunity. The onset of the drowsiness, is relatively quick but it doesn't last should you get distracted. And yes, your dreams may become "interesting".