I wouldn't do it. I once took Ambien on a flight and did not fall asleep, and was miserable, knowing I couldn't functionally get up for hours. One of my friends, an MD no less, took it on a flight and does not remember his business class meal all over his lap, food all over the place - there are photos. And most importantly, "it is going to be a 9+ hour flight..." Rather, it is scheduled as such. When I see people popping their pills, pre-departure, I think of what fools they must be, as none of us have ever had a mechanical and had to disembark. More importantly, I am reminded of a HNL/SFO flight once upon a time, when I departed HNL at 10pm or so, and landed back at HNL an hour later with a parade of fire engines awaiting our landing. All reasons why I don't want to be any more than Benadryl drowsy, or have a few cocktails of impairment while traveling.