Sleeping is the standard way to recover energy in the sims, but it takes so long...There are two ways you can avoid sleeping at all, but still top off your energy quickly. here they are.
#1- Coffee machine or Slushrush smoothie counter
One of the best ways to prevent energy from falling to zero is to guzzle coffee or slush drinks until you have a full bar. I recommend the smoothie bar over the coffee machine because it not only restores more energy, it also restores comfort and hunger. Beware, though. you need to use the toilet often while topping off your sleep gauge.
#2- Bug zapper
Ever wondered what good the bug zapper was actually FOR? well, in addition to providing mild amusement for your sim, it can "recharge" his batteries. Touch the bug zapper about 6 times, and you have a full energy gauge, even from zero. painless, right? well, actually, it wasn't so painless for your sim. comfort has probably dropped to zero after you get done, so recover it with a dip in the hot tub or a nice sit on the couch.