) and Deloitte Consulting are among those that encourage employees to add a midday snooze to their to-do lists. Sleep scientist Sara Mednick applauds this trend. Mednick, a researcher at the Salk Institute for Biological Studies in San Diego and author of the new book Take a Nap! Change Your Life (Workman Publishing), says napping can enhance productivity. She explains how to Associate Editor Arlene Weintraub.What are the main benefits of napping?Research on sleep deprivation shows that even at six hours a night, there are all sorts of changes in the body. Insulin rises to pre-diabetes levels. There's an increase in heart disease. Without sleep you don't learn. My research shows that people deteriorate during the day. It's difficult to sustain productivity. Naps can add back to the sleep you're deprived of at night. And a nap enhances productivity even if you have enough nocturnal sleep.You describe an "optimized napping formula" in your book. What is that?A nap involves different stages of sleep that lead to different kinds of improvements. Rapid eye movement [REM] sleep, for example, is good for improving creativity and perceptual ability. Slow-wave [deep] sleep is good for restoring muscle function. The formula helps you harness those.So what would be the optimum nap for a middle-aged executive working long hours?A 20-minute nap in the afternoon, between 1 p.m. and 3 p.m., right after lunch, would be ideal. You don't want to get into deep sleep, because you need to be alert. This nap will allow you to be as productive right after the nap as you were before. That's what a lot of businesspeople need for on-your-feet thinking.If your office isn't set up for napping, how can you nap?Find a room where no one can disturb you. Turn off your e-mail and phone. I nap on the floor of my office, with a pad and a blanket. I'll also nap in the car. If I have a meeting, I'll get there 15 minutes early and set my cell phone alarm to wake me up.What will it take for napping to become an accepted practice in the workplace?It has to come from CEOs recognizing that this doesn't take away from productivity. It's not an embarrassment. I compare it to telecommuting. When that began, it had a bad name. Working at home was for people who were lazy. Then CEOs realized they were getting more from employees who were allowed to work at home. I predict the same will happen for napping.What do you say to people who have trouble napping during the day?I tell them to get rid of nap blockers: too much caffeine or alcohol. There's nothing wrong with that morning coffee at 7 a.m. or 8 a.m. if you're going to nap at 1 o'clock. But while alcohol makes you tired, it disrupts the sleep cycle. So no martini lunches. And you need to remove the mental blocks--thinking you're not being productive or that you're being lazy if you nap.Some people are afraid to nap because they'll feel groggy when they wake up. How can they avoid that?That's called "sleep inertia"--the inability to shrug off sleep. It increases as you go deeper and deeper into sleep. So the trick is to avoid getting into deep sleep. If you nap about 20 minutes, you'll be in light sleep, which is easy to get out of. Or you can sleep longer, say about 60 minutes, to get out of deep sleep and into REM.Some sleep experts say people who have trouble sleeping at night should not nap. You disagree. Why?For the most part, the research has found that napping does not interfere with nocturnal sleep unless you havesevere insomnia. A 15-minute nap at 1 p.m. won't prevent you from sleeping at 10 p.m.You describe a tactic called "extreme napping." Explain.In some situations, where there's a lot of stress, some people can't fit in core nighttime sleep. Extreme napping is a way to regulate short amounts of sleeping and waking. So you could, over 24 hours, take a 1 1/2-hour nap every 8 hours. It can be successful, but if you don't do it right, you could get sick. I recommend it for short-term use only--say, if you're under a deadline or you're attending a conference. Ultrashort sleep is a way to make sure your body gets enough.