Does the mood gizmo make it so you don't have to sleep?
It does when the exhausted moodlet appears, you can max out the energy bar with it when you do that! Some say you can do that with the mummies curse too.
Once you are a mummy, your energy bar turns into some weird looking design and you never need to sleep... but you move at like 1/4 your normal speed, so you end up losing SO much time just getting around that to me it really isn't worth it.
I will have to get M&M's for all my sims now... MMMMMmmmmm M&M's aaaaaaaaaalllcggghhhhhhh!!!! <--- Homer Simpson drool sound