I learned to sleep with my eyes open......

I would say it depends a little on your work. If you have a desk job or something that is not physical then getting up, moving about a little, stretching and performing some simple physical exercises can really help wake you up. You might look a little silly while performing them in a work place, but it might be worth it. If your work is quite physical already though I'd say the most important things are what you do outside work. Keep a regular sleeping pattern and be sure to sleep well, make sure you eat healthy meals and at not too large intervals to keep your energy up throughout the day. When you sleep make sure that it's quality sleep, avoid TV and monitors for a period before you go to bed and avoid eating any large meals right before bed. These things also apply for the situation above although it requires more planning. Some people might recommend coffee, that however is a bad idea. The feeling of coffee waking you up that coffee drinkers get is actually a return to their normal state, because if they don't drink coffee they start "detoxing" and it makes them feel tired. http://voices.washingtonpost.com/checkup/2010/06/does_caffeine_really_wake_you.html My knowledge of grammar isn't that great so I'll leave that up to someone else. I can make a few comments though. In the first sentence I'd probably insert "What do you do when you're sleepy in the afternoon?" or "What do you do when you feel sleepy in the afternoon?". For the next line I would probably use notify instead of notice. You could replace "not sleepy" with "awake" in the second to last line.

What do you usually do when you feel sleepy in the afternoon? As a teacher, I can't afford to be sleepy in front of a class!