Mac wakes up periodically from sleep... huh?
My new Mac, running the latest OS X Mountain Lion 10.8.2, periodically wakes up from sleep and does something, then goes back to sleep. What is going on?
Mac Pro, OS X Mountain Lion (10.8.2)
If you have 'Wake for network access' selected in the Energy Saver Control panel your Mac will occasionally wake from sleep for short periods of time to maintain network registrations.
http://support.apple.com/kb/HT3774