I don't like to take naps. Well, let me clarify: I love naps. But I don't like waking up all groggy. So a 'coffee nap' sounded interesting to me.
A coffee nap is exactly what it sounds like: You drink a cup and then immediately take your nap. While this may seem counterintuitive, the caffeine in coffee doesn't kick in for about 30 minutes, so dozing off just after you drink your java is very possible. And that short sleep will provide its own energy punch: Power naps have been shown to improve alertness and performance.
The ideal coffee nap is 30 minutes long, which means you're waking up just as the caffeine starts to work its magic. The result: You feel both rested and stimulated.
(Health)