I'm grateful to be able to travel, but I hate long-haul flights in economy, which realistically, is the cabin I'm most likely to be buying tickets in. And it's not because I'm fussy about the food or entertainment; it's down to not being able to sleep.
I drink lots of water, wear compression socks, and move around as much as I can, but I generally feel so uncomfortable (plus restless legs, bloating, and sometimes swollen ankles) that sleep eludes me. I lived outside the UK for ten years, so I've lost count of the number of times I've flown through the night, sitting up in pretty cramped conditions of economy, and not managed even an hour of rest.
