I can relate to this as I'm going on the flight that took over from yours as the world's longest: Auckland-to-Doha on Qatar Airways. And for anyone who thinks the Travel team fly only business class, I'm booked in for economy class all the way.
For a start, choose your seats before you go. I always consult Seat Guru for the layout of the plane to help decide. The window is better for sleeping, as you can lean against it. But the aisle is good if you don't sleep all that well and want to move around.
During my time working in Travel, I've become obsessed with creating the ultimate carry-on pack for a long flight. One essential is noise-cancelling headphones. They take up a bit of space, but are so much better than those provided by the airline. I put them on, start up a nature doco or dry drama, pop a sleeping pill and before I know it, I'm out like a light.
Not everyone recommends sleep aids, as you can be a bit dazed and confused when you arrive, but with 17 hours, it should have worn off once you get there and you'll have your well-rested boyfriend around anyway.
Some people, Travel Editor Winston Aldworth among them, recommend having a few drinks but I find that makes my sleep worse.
Invest in a decent travel pillow. They look dorky, but really make all the difference. An inflatable one is more practical space-wise, but I still think you can't beat the bean-bag type ones. Don't get a cheap one. I got a cute Totoro neck pillow in Vietnam and had the unpleasant experience of it bursting on my flight home. Little bits of plastic everywhere. Luckily my fellow passengers had littered the aisles with sunflower seed shells, so I didn't feel too conspicuous.
I also try to get into the time zone I'm going to as soon as I get on the plane and only sleep at the appropriate time. It helps lessen the jet lag at the other end.
What are your long-haul sleeping tips? Send them in and I'll publish the best.
We've had lots of responses about North Korea and we'll share them next week.