Drink a cup of coffee. Lie down flat in your clothes. Get up in 20 minutes.
Do this early in the afternoon (about an hour after lunch) or whenever when you’re feeling logy but not sleepy. The trick is to sleep just enough to feel refreshed but awaken quickly and to a state of alertness, instead of becoming disoriented with oversleep. In short: sleep long enough not to dream.
Drink a cup of coffee. Counterintuitive though it seems, it takes 20 minutes or more for caffeine to kick in. This gives your body a natural alarm clock.
Lie down flat in your clothes. Sleeping while sitting or curled up could give you a cramped neck, or make your muscles stiff. Changing into pajamas will prompt you to extend the nap more than 30 minutes. These are all bad things. I try not to cover up (with a blanket or such) or lie in a room that’s too cool, either.
Get up in 20 minutes. The coffee in Step 1 should take care of this automatically. If not, lying flat without covers in your regular daytime clothes should ensure pretty shallow sleep.
This is better than a coffee break. As a late-night and early-morning person, my body’s energy hits a long ebb during peak business hours (usually 11:30 to 5:00 pm). When I can set my own schedule, taking this kind of nap at about 1:30 gives me enough gas to power through to my early evening second wind.