It’s an interesting question. But since doctors don’t really know the answer, you’ve caught the scientific community napping as well. Even so, several things come to mind.

The first thing to consider is the possibility that you nap because you have daytime sleepiness. If so, then what might be the cause?

• Do you take any medicine that might make you sleepy? Review your prescriptions with your pharmacist or next time you visit your doctor.
• Have you started having problems sleeping at night? If you sleep well at night and wake up refreshed, don’t worry. But if you feel groggy or have early morning headaches, you may have sleep apnea or some other cause of interrupted sleep.
• Could you be depressed? Ask yourself if you no longer enjoy activities that previously gave you pleasure, and whether you are feeling low.

It sounds as if your nap is voluntary and enjoyable. So it probably does not reflect an underlying sleep disturbance. If it refreshes your day without making it hard for you to sleep at night, snooze away.

For most people, a 20- to 40-minute nap between noon and 4:00 p.m. is the best way to catch a few winks without disturbing the sleep-wake cycle. But remember to give yourself a good 10 minutes to wake up gently before you engage in mentally or physically demanding tasks.

When NASA and the FAA studied napping in airline pilots, they found that napping improved mental alertness and performance. Many night shift workers are also perked up by naps as brief as 15–20 minutes.

Do naps improve overall health? Napping is the exception in America. But afternoon siestas are the rule in many Mediterranean and Latin American countries.

Scientists have learned that blood pressure drops during a siesta. But it rises abruptly on awakening. Is this meaningful? Probably not, but we can’t be sure.

Until doctors dream up a way to resolve the contradiction, there is no reason for you to deprive yourself of a pleasurable nap.