i had tried two bottles in the past and that was the first time i had taken zma. I really liked the stuff and slept like a baby while i was on it. I did try other brands such as Eas's and biotest's formula but did not experience the results like i did with cytodyne's. What I really liked about their formula was that i always had the most vivid dreams that i've ever experienced . i never experienced that with eas's or biotest's. i give zmass-pm a thumbs up