Drink lots of water before going to bed - stops the dehydration.
Next morning, a full fry up! Bacon, eggs, sausages, bread, black pudding etc. It may be a case of kill or cure but seems to work for me.
If all else fails, Resolve is worth a go - I think it is basically glucose but again, seems to do the trick.
Do not on any account try the Dutch idea of a raw herring with onion especially if you fancy getting back into bed with your partner!
Best of luck.
McC