Some people suggest having a few drinks to relax before flying, especially when going on holiday. As a very frequent traveller I learnt several years ago that alcohol and flying aren't a great mix due to the increased affects from being at a high altitude. To arrive refreshed, don't drink alcohol and do drink water in abundance, you'll get over the jet lag considerably more quickly and be free to enjoy a lot more of your time.
Hangovers at altitude are the worst I've ever had. Woke up after a transatlantic flight in First with US Airways having parties in NYC and then continued drinking champers onboard, and my head hurt for days.
