I know it's annoying but people snore, it's a fact of life and they have no control over it at all.
Unfortunately I am a snorer especially if I have had an alcoholic drink, or I've got a cold, or hayfever, or my asthma is particularly savage that day, or if the air is very dry as on a plane.
I don't like doing it, I wish there was a magic cure but there is nothing I can do apart from staying awake, and on an overnight flight when I've spent the whole of the day working it wouldn't be possible for me to stop myself sleeping. I think it's ridiculous for people to suggest that people who snore should stay awake on long flights.
I also hate listening to the other snorers (in actual fact I find it very difficult to sleep on planes even in international business class) but I just pop in some earplugs, or my headphones and accept that I'm on public transport.