Using Sleep mode or Energy Saver is _not_ recomended on any Mac based DAW, or audio system.
PCI based systems, like ProTools Mix, Digi001, MOTU PCI324 have problems when Sleep or Energy Saver is used. Drivers for these cards can become corrupted, or the PCI cards will not allow the computer to truly go into it's low power mode... which we've found causes unstable behaviour.
We've found that corruption of preferences is most common. However, application, driver, and system corruption occurs as well.

We suggest setting Energy Saver to NEVER (so that it never sleeps or shuts down on it's own). Digidesign and MOTU recommend this as well. As an alternative, either turn your monitor off, or shut the entire system down.