Hope I'm not duplicating but haven't seen this adequately addressed elsewhere. Sleep works just fine on my mini; whether closing the lid or choosing sleep from the apple window, the mini goes right to sleep and wakes right up when opening the lid. However, when per my battery power/energy preferences display goes to sleep for more than 15 minutes or so, I can't get the display to wake back up and have to do a hard shutdown. Power button stays solid the whole time unlike with sleep when choosing from the apple menu or closing the lid where it happily snores away. No amount of keyboard activity or trackpad activity can get the mini to come back. I do much writing while reading and thinking much in between paragraphs and need these energy settings for battery life. The computer sleep is checked to happen at 15 minutes, the display at 10 minutes and "hard disk to sleep when possible" is enabled. So what gives? To repeat, sleep works fine for me when induced from closing lid or choosing from the apple menu.