• 34% of adults in the U.S. say they take a nap on a typical day.
• A person who dreams during a short nap is likely sleep deprived.
• As we age there is a tendency to take and be satisfied with shorter naps.
• Ideal nap time: 1pm – 4pm.  Napping later in the day can interfere with falling asleep at night.
• A 10-20 minute nap packs the most punch. You can feel groggy after 20-30 minute naps. A 60 minute nap may do more harm than good.
• To avoid a deep sleep, it’s best to sleep slightly upright

Read more @ wsj.com: The Perfect Nap: Sleeping is a Mix of Art and Science