Welcome to SF! mcb3030
In order to have the defragmenter running a scheduled run should actually be waking Windows out of sleep mode once the tool is started. The sleep mode itself is simply a power management option for power saving when the system is idle after so many minutes of inactivity.
Once the scheduled run starts the hard drive activity will come about while the display may not come out of sleep there. The way to wake a sleeping pc is to simply move the mouse, use the touch pad which wakes up the display and perform some other simple task waking the hard drive.
Actually unless you are performing a great deal of file transfers, downloads, uploads, creating new files, deleting fiiles, moving, copying file here and about the drive should be found at 0% to start with. This was first called the PreFtech in XP, later SuperFetch in Vista, and now 7 where the defrag tool runs at a low usage rate in the background being preloaded by Windows.
When simply ignoring the 5 sata drives in the desktop here for over a month the analysis showed 0% on all 5 HDs were one never saw the defrag run on it in ? try a full year's time on that one!
