I thought it was family and friends strictly for alpha? I HATE MOBA's but....I have loved warcraft and Blizzard since 2000 so I am sure I will be playing it at some point lol.
What is your laptop sitting on? Could be overheating in middle of the night?
Also while researching I found this
http://support.microsoft.com/kb/920730
Could be a hibernation issue and not sleep?