I had a pretty bad one when I was flying from Helsinki to Bangkok years ago; was seriously wondering if they'd let me into the country Nah wasn't that bad, but I really felt like crap. Too much whisky, dry cabin air, dehydration, high altitude... It sucks. So I only drink beer on planes ever since then.
That said, I have no trouble sleeping on planes (or anywhere else, for that matter), whether sober or not.