It depends on what you plan to do next. If you know you'll do something that'll need your body strength, coffee is not good as it'll weaken your body.
Eat more vegetables and avoid meats in the breakfast. Drink plain water and not other beverages. You should be able to maintain your consciousness up to noon.
And if there's less that 3 hour left for sleep, don't sleep at all. In that way you'll get extra 3-4 hours of clear mind to do whatever is left.
If there's something important to be done in the afternoon, half day leave is recommanded.