Before i went to sleep I put my mac to sleep - I didn't close the lid however. This was around... 11ish, pm. I woke up at around 2:30 due to not being able to sleep and went to wake my mac up, however, my mac didn't make it's usual sound it makes when it's woken up from sleep mode. Instead, my mac went silently to my password authentication box. It only does this if i have left my mac on for a long period of time and it has gone into sleep mode/or the screen has gone black, without my assistance. When i entered my password and the screen popped up everything was how i had left it but there was a pop up above my TextEdit window which mentioned something about log out timing out. The reason im puzzled is because I put my mac to sleep, without a doubt, and dont understand how it has obviously woken up in the night? Is it possible my mac ran some kind of update, tried to restart itself but couldnt as i had not selected to save or discard my work in text edit, and therefore timed out? However, i checked the date of my last software update and it's not compatible - last softward update occured last week. So along with my previous questions, i'm curious to know whether there any other forms of updates that can occur to my mac whilst it sleeps? It was sleeping between 10pm and 2:30am. And if so, does it generally put it back to sleep? I just don't understand why it went straight to the password window without making that sound - only conclusion i can draw from it, is that it woke and ran some kind of.. update.