I've bad and good experiences with Ambien. I typically use it on long red eyes, like US-Asia. As it is a hypnotic, I sometimes feel like I am just zoned out, or semi awake, instead of sleeping. More than once I've said to myself, "the Ambien didn't work, I didn't get hardly any sleep," and then I look at my watch and realize that 4 or 5 hours have passed without any memory of them. I've also had weird hallucinatory events with Ambien, like opening my eyes and believing I was at an ice cream social in a church basement instead of on a 747. I have also had amnesia events, like not remembering deplaning and doing the luggage carosel, later in the day.

It kicks in very quickly for me after I take it. I have learned to never take Ambien until I'm ready for sleep immediately. Alcohol, for me, greatly amplifies the effect, at least at first. One time, as the dinner service was beginning, I decided to take my Ambien as the carts were headed in my direction. I figured it would be better to take it on an empty stomach (don't think it much matters, actually). A few hours later I awaken and say to my travelling companion, "are they ever going to serve dinner". She looked at me and said, are you nuts, they served dinner two hours ago and you ate it and drank two glasses of wine. I had no memory of it whatsoever. Spooky. So, I still take Ambien, think it helps, but I am cautious, and prefer to be travelling with someone who can watch over me.