Achieve-IT!: How to Take A Caffeine Nap
http://goalsuccess.typepad.com/goaltips/2006/02/how_to_take_a_c.html
"The Caffeine Nap is simple. You drink a cup of coffee and immediately take a 15 minute nap."
MJ PEAK PERFORMANCE: Snooze, You Win - Improve your mental and physical performance by power napping
http://www.mensjournal.com/healthFitness/0601/napping_power.html
"You must keep the nap to 20 minutes or slightly less, and if you need the extra sleep, wait until the 50-minute mark."