There are surprisingly few ways to increase energy levels in this game. And yes,
(imitating my mother's voice) "There are no substitutes for planning ahead and getting a good night's sleep on a high quality bed."
Munching on some of the herbs from Uni can help a little, but much like coffee or eating coffee beans, that really just stalls the energy depletion when levels are at or near the bottom and unless you grow or find high quality herbs, there is Herb Nausea to contend with. Then there is the miracle of TrimaSim pills:
http://modthesims.info/download.php?t=455990 (warning: do
not take on an empty stomach, could be fatal!)
But the mod you were probably really looking for is here:
http://modthesims.info/d/520627
Of course, it could be argued that instead of popping pills and washing them down with coffee every day, one could use testingcheatsenabled and drag the energy bars of our sims up ourselves. Yes, that's cheating but so are the pills. We are really meant to snooze our sims better and at the appropriate times of the day/night for their work schedules.