There's a right time for everything—including napping on the job. In his book When: The Scientific Secrets of Perfect Timing, Daniel Pink reveals the formula for taking the perfect nap, what he calls a nappuccino.
First, chart the times of day when your energy plummets. Do that for a week to discover your ideal nap time. Then unplug, isolate yourself from sound and light, chug some coffee, and enter dreamland for 25 minutes and no longer. Napping for more than 30 minutes leads to sleep inertia, whereas, Pink points out, shorter naps offer the benefits of increased mental function and alertness.