I think napping is great, when you can! My dad, a doctor, used to be a devotee of the afternoon nap (on weekends, after a sandwich and beer, what a luxury!)—which, I discovered later, is also recommended by the Ayurvedic tradition (eastern medicine) for the physiology of the body and the recharge of the mind.
The siesta is practiced in many forms throughout the world (from Europe, in Italy; throughout warm places like the islands of the South Pacific to East Asia, in India—where ayurvedic medicine recommends you lay on a particular side after eating for better digestion).
ON a personal level, when I was working as a horse wrangler (quite physical) and training as a competitive canoe paddler for a long-distance race, I used to take a short nap before practice and it really helped my performance.
I now work in television and film, and we often work outrageously long hours—so a 15–30 minute nap can get you through a long shoot; I have heard 38 minutes is the max you wanna ‘nap’ because if you stay asleep longer, you switch gears and go into a deeper level in your sleep cycle, and therefore will feel grumpy for being interrupted if that gets cut short.
Nap time also in kindergarten (and pre-school) seems pretty essential to keeping the peace and replenishing the brain trust!