Yes, naps are a very good thing! Keri Glassman covers some of the stats on naps in this 1 minute video. An ideal time is around 26 minutes and it not only boosts your productivity but has other benefits as well. I LOVE taking naps in the afternoon.
In some cultures naps are much longer and called siestas are part of everyday. For example, in Spain they have a 2 or 3 hour siesta in the afternoon, then stay up later at night. Everything closes during the ‘siesta’ time.