Every Lunchtime !
I eat my lunch in the van, then have a large black coffee to wash it down - though a Red Bull works just as well. Set the alarm on my watch - Then have a nap for 20 mins, when you wake up the coffee / RedBull has just got in your system and you're buzzin' and ready to go for the afternoon !
Got that from an American cycling coach who swears by it every day - takes the caffine 20 mins to react with your body, so when you wake up from your 20 minute nap you are on a high. Any longer than 20 mins and it doesn't work - 4 hours is overdoing it !
Don't try Nescafe Decaf though - doesn't work
Dave.