The Perfect Nap: Sleeping Is a Mix of Art and Science
online.wsj.com
online.wsj.com
When I started taking shorter, more controlled naps(similar to the suggested in the article) I found it much easier to come out of the nap refreshed, and not nearly as tempted to roll over for another 15 minutes of sleep (as we all know where that leads).
I used to avoid naps, primarily because the block of sleep wasn't worth being up all hours of the night and dragging myself out of a funk once I woke up, but if you start playing around with different schedules and durations that work best for you, they can be very helpful for focus and productivity.