I don't know how a software would know the backups are complete. Sometimes the backup take 10 min, sometimes they take 2 hours.

anyway, energy saver is fine -- except does anyone know why in 10.5 set to Never you could sleep at night, but with 10.6 set to Never you cannot sleep?

Kevin's original solution is fine except I wonder what would happen if I woke the computer after the 11pm schedule to sleep/ sliders set to never.
I would then have to do a manual sleep. With Snow Leopard I may have to manually redo the sliders -- big hassle.