Made this just to see if it was possible. Hooray! It is. Makes sleeping twice as fast, no matter what your sim is sleeping on (So a cheap bed that takes, say, 9 hours will now take 4.5 to fill the energy bar, and an expensive one that takes 7 or so will now take 3.5.).
It lets my sims stay up pretty damn late at night and still get up for work. Great for sims with a LOT of stuff to do...like gardening...which takes for-freaking-ever.