My PhD advisor likes to drink a coffee just prior to falling asleep. That way the caffiene slowly kicks in and wakes him up. I can't do this--I already have trouble sleeping and I feel the effects of coffee quickly.

But to answer your question-- for me, washing my face helps a lot. I don't know why. Not that I nap all that often.

I am groggy but I drink a Coke Zero and within 10-20 mins I feel great. Whereas without sleep I would be flagging.