Does cron do its work if the CPU is sleeping

[Carter Tomassi]

I leave my G4 on with the Energy Saver set to put the computer to sleep 
in one hour and the monitors less than that. And "Put the HDs to sleep 
when possible."  is  also  checked.

Is cron still re-activating the CPU and HDs at around 4 a.m.? I am 
something up at that hour and never have heard the drives starting up.

TIA,
Carter