The siesta cultures near the equator may have it right. It turns out a mid afternoon nap is not such a bad idea. In fact, we may have been meant to sleep in the middle of the day. Although many believe that the mid day slump we experience is due to a heavy lunch, that is not the case. Sleep researchers have found that our bodies experience a slight drop in body temperature and a readiness to sleep in the afternoon regardless of whether we slept well the night before or not.
We often cover up and push through the urge to nap with caffeine and an afternoon snack of carbs (one reason why Starbucks and vending machines do so well).
Research suggests that we can benefit from a ten minute to a forty five minute nap in the afternoon so long as it is no later than 4:00 pm. Benefits from a nap include alertness and an improved mood.
So if you are able to do so (and keep your job), take that nap!
Resource: Say Goodnight to Insomnia, by Gregg D. Jacobs, Ph.D, Pages 96-98