I find it also varies on my mood.

If I am already fairly tired befor a long haul (ex LHR) then I won't bother and I try to limit myself to 2-3 hrs sleep so at least I can function until a reasonable hour at the far end.

However, sometimes I feel wide awake so I may have a 2 of the bottles of wine (WT/WT+) or a few glasses (J) to help me nod off. Then when I wake up, lots of water to rehydrate.

Coming back from the US, I don't often drink as I try and stay up late the night before the flight to make myself naturally tired.

It's a tough call and will vary per person, but definately lots of water will help combat the effects.

Does it really enhance dehydration to drink alcohol on a plane? Why are the effects supposed to be that much worse?