Hey man,
Just wanted to let you know that I feel your pain on this. The last couple of weeks I've been noticing some really nasty dark bruises under my eyes. Even though I sleep 8+ hours a night and drink plenty of water, it's not going away.
I was doing a lot of Google searching on the subject today. I'm pretty sure I have what's called "allergic shiners." The dark bruises and puffiness are caused by allergies and nasal congestion that comes with those. So there's not much I can do unless I treat the root of my allergies, which has been an ongoing struggle since I was an adolescent.