It’s pretty easy to become the master of the caffeine nap. The idea is simple enough: drink a cup of coffee, then take a 15 minute nap. It takes a little bit for the caffeine to kick in, so this oxymoronic combination isn’t too far-fetched. Then once your alarm goes off 15 minutes later, you wake up refreshed and ready to battle the monsters of the day.
The caffeine nap isn’t just a concept though. It’s a real scientific “thing.” Sleep researchers at the University of Britain put several fatigued drivers in a driving simulator to determine the best ways to make them more alert. Apparently, there’s a chemical in your body called “adenosine,” which makes you sleepy. Coffee chases this chemical away, which is pretty cool.
Info from: http://www.sleepdex.org/caffeine-nap.htm