First, plenty of water.

Yes, plenty of water, and no refined anything. . .have an apple every so often between (healthy) meals. Stretch. get out for a short walk every few hours.

Just a touch of caffeine, but not too much.

Oh, wear sunscreen. No wait.

Cold water, that is. Applied to the face at regular intervals.

Nah, bunnyfire's right--I find I have more energy when I drink lots of water, which I rarely do at home (but drink 2-3L/day at work. Go figure.)

Do you have an office-type area at home that you work in? I found that otherwise I'd be constantly distracted by chores/laundry/whatever that needed doing.

On preview, seconding what danf said, too. Unless you're a coffee fiend, in which case...

One hard-boiled egg.

Save the sugar loading until after 3pm or so, that way you may get the boost, but finish before the crash.

Oh and on the caffeine thing, military studies have shown that maximum productivity results from slow constant low-dose caffeine, such as caffeinated chewing gum.

Or tea. That was the other thing I was going to say. YMMV, but I find tea much less of a caffeine roller-coaster than coffee. Just try not to finish the second pot by noon.

I swear I learn something new from you bunnies everyday on this thing. I had no idea there was such a thing as caffeinated chewing gum.

nth-ing the water. And getting up and moving around, even if out to the mailbox and back. Maybe some music you don't normally listen to. And a tablespoon of peanut butter to go with one of those apple snacks.

And now on a purely speculative note, I've been wondering if replacing all my sucrose, fructose, etc. sugars with pure glucose (only available from beer brewing stores as far as I can tell) would have any benefit on brain function.

Jolt Chewing Gum