27" iMac HDD Spinning up randomly while sleeping

I can NOT figure out what is causing this but my 27" imac is in my room and during the night it seems like the harddrive spins up (I can hear it) every 30 minutes or so. I've tried to figure out what it is and can NOT figure out what it is for the life of me.

I am using WIRELESS connection if that helps at all. Disabled bluetooth..thats all I can think of.

-Matt

Try checking in the power settings to see if you have it set to turn the drives off when your computer is not in use. That might be the reasons that the drives keep coming back on.

In the Energy Saver menu::

"Put the harddisk to sleep when possible" is checked.

Wake of network access is NOT checked...

That is weird, the only thing I could think of could be if you have certain programs to check for updates every ... so if it is on a regular schedule it could be waking up to check for updates?