I will be flying to Hong Kong in two weeks and since this will be my first long daytime flight, I'm not sure how I should prepare for it. My flight leaves at around 3pm and arrives the next day in Hong Kong at around 7pm. I already have enough trouble sleeping on overnight flights, I can't imagine how I will survive a 15 hour long daytime flight. Should I stay up the night before so that I can possibly sleep on the flight or would that be a bad idea since I will arrive in Hong Kong in the evening? Any tips?

I will be flying in economy which makes things even more difficult. It should be an interesting experience to say the least!