If you’re very tired and can’t keep your eyes open, researchers at the Loughborough University in Britain found out that the combination of a cup of coffee with an immediate 15 minutes nap afterwards provided the most alertness for the longest period of time.
This is called The Caffeine Nap, and was deemed by the researchers as the most effective method for tired drivers to keep themselves awake.
I’m a big believer in power naps. Snoozing for 20 minutes really gives me a boost after lunch time. Here’s an article that categorizes naps and explains the different benefits of each kind of nap.