One more question regarding mounting drives

[rock15478]

I can't really set my computer to sleep (time out) automatically because I use it as a production machine and the software I use specifically says to turn off the energy saver and option to sleep when not active, so I always have to do this manually.

What would you recommend doing? I'd say this machine gets used 4-5 times throughout the week and I have it set to run nightly backups. I have a Lacie drive that is specifically for backups. Would you recommend leaving the drives unmounted when not running? Should I turn the drives off when not in use or leave them on? (They still make sound even when they're unmounted)

Is there any way to let these drives unmount before sleeping the computer?

Thanks for the help.