Drink lots of it. Preferably before, during, and after your little soiree. Alcohol can dehydrate you, so make sure you definitely have some before switching out the light.
There's not actually a cure for hangovers, but you can certainly ease the pain. For some people, coffee is a must. But if you don't drink the black stuff, most hot drinks can give you much needed boost.
A fry up
Hopefully you followed the most ancient party rule and had a decent dinner before you went out. But if not, the traditional fry-up can sort you right out. Concerned about snotty eggs? Cook it yourself.
No one's expecting you to spring out of bed for a swift 10k, but getting up and getting active can cure the worst of things. Sweat that badness out with a walk, swim, or even a few laps of the garden.
While scientists are yet to prove, or perhaps even bother testing this, we're pretty sure that cuddling a dog when you're feeling sorry for yourself is the best way to cure what ails you.