"I often commute on the bike and when it comes time to head home I feel a bit lethargic. Outside of caffeine, any recommendations for getting my engine restarted for the ride home?"
I commute on my bike(s) to work quite often. Some of the things I found to help:
-Try not to skip meals
-Keep muchie food at your workplace so you can at your choice munch something before heading out.
-If necessary, chill out at the workplace a while before heading out. I don't like spending any more time at work than I have to, but sometimes I can tell I need to collect my thoughts, even if I'm just staring at nothing for 5 minutes.
-Drink water through the day to keep hydrated. Riding dries me out pretty quick. Don't just drink before heading out, drink water (I try to avoid cokes and the like) all through the day.
Funny thing about dehydration is you don't feel thirsty until you're aready in the beginning stages of it, and it's tougher to catch up once you've fallen behind. Therefore, I try to drink water with a large glass mug (about 2 1/2 coffee cups worth) at a time, not 2 seconds of slurping at a water fountain. I'm a hefty guy (230 lbs?) so what amount of water works for me may not work for you.
I figure I'm drinking enough if I have to urinate several times a day and it all comes out clear or close to clear. If it's dark and smelly, that's a sign of dehydration.
...and by the time I ride home, which isn't far: 11 miles, I usually get another big glass of water as soon as I'm in the kitchen, because by this time my mouth is starting to feel dry again. In other words, I make this an all waking hour habit of drinking water.
At some point I heard another good reason to drink water this much: it helps keep kidney stones from forming. I haven't had a K-stone problem but I know a guy who didn't listen to his doctor to "drink water, lots of water" and he had 2 kidney stones in the same year.
I dunno if this will help your before ride home lethargy, but it can't hurt.