So this refers to my new 2011 imac i5 27 inch. Usually, when I turn the computer back on from sleeping, I can hear the harddrive's "rumbling" slightly and I know it's waking up. There were a few instances where I thought I didn't hear that "rumble." So I went into terminal and checked the imac's "wake reasons". To my surprise, it didn't record the wake reasons for those two times, which led me to think that it wasn't sleeping when it should be. I have it programmed so that it sleeps 15 minutes after being idle. And those two times, the computer was supposed to be sleeping for over 8 hours. Is there anything wrong? I did close most programs (maybe just safari was on?). Thanks in advance for any advice!