The sleep experts say a 10-20-minute power nap gives you the best "Brain Reboot" but depending on what you want the nap to do for you For a quick boost of alertness, experts say a 10-20-minute power nap is adequate for getting back to work in a pinch. For cognitive memory processing, however, a 60-minute nap may do more good, Dr. Mednick said. Including slow-wave sleep helps with remembering facts, places and faces. The downside: some grogginess upon waking. Finally, the 90-minute nap will likely involve a full cycle of sleep, which aids creativity and emotional and procedural memory, such as learning how to ride a bike.