I've been advocating a midday nap for years. It's pretty obvious that it's beneficial. Luckily i've lived 10 minutes away from work for about 2 years. So on those days when I feel especially sluggish, I can go home and take a quick nap, and then face the afternoon refreshed. That's the only good thing to come out of the useless 1 hour lunch that I have to take. It's never taken me longer than 30 minutes to eat lunch.