I'm really envious of people who are actually able to take naps because it just doesn't work for me. By the time I actually "phase out", for which I need at least like 20-30 minutes, most of my lunch break would already be over, resulting in me waking up all groggy and irritated.
Being able to sleep anytime, anywhere is basically something you can train to. When you do, it's extremely powerful to stay alert. As a starter you don't have to make actual naps, just close your eyes and rest for a few minutes.
You maybe know about any good online resources for nap training?