What causes our eyelids become swollen when we are tired or hungover?

[duketheduck]

Does anyone know what the physiological reason behind this is?

[lillie]

I'll have a go at this: I think it's something to do with the lymphatic system. It is partly responsible for draining toxins and when you are tired it slows down and is less effective and then everything goes all puffy. Also, when you are hungover you are dehydrated and that causes water retention (your body is building up as much water as it can), and again that makes eyes all puffy. I think this is the reason, but don't quote me on it. By the way are you Anna - and why did you change your name?