How To: Get your MacBook Pro to sleep in OS X Lion
Pre-OS X Lion, all I needed to do to put my 2008 MacBook Pro to sleep was close the lid. However, since upgrading Lion, I’ve noticed that it never really seemed to go to sleep anymore, especially when plugged in to a power source. I would be watching TV and hear the sound of my MBP’s fans whirring from across the room, and even though the lid was closed and I assumed it would be asleep, when I opened it I would find it was actively running a Time Machine back up or a Sophos Anti Virus scheduled scan or something. I would also still see it on my network as an available share. A couple times I even noticed it happening while on battery power – and on one emotionally scaring occasion I removed my nearly scalding-hot MBP from its laptop bag to find the fans whirring and the battery down to 8 percent.
I’m not sure if this behavior is specific to my model of MacBook, or just my MacBook in particular (I had modded it in the past by removing the optical drive and adding an SSD drive – no idea if that is to blame or not), but it was annoying, and had worked fine in Snow Leopard. After doing a little sleuthing, I eventually found the cure, which seems to make no sense, but I can’t argue with the results. So if you are having the same problem, let me know if this works for you.
Step 1: Open System Preferences, and Click on SHARING
Step 2: Uncheck EVERYTHING that is checked.
Step 3: Close System Preference.
Step 4: Open System Preferences > Sharing, and re-check whatever you want.
Problem solved. (For ME at least).
I have no idea why this unchecking/rechecking of options would work, but it seems to have done the trick for me. Good luck.