Try this next time. Change the power settings from SLEEP to HIBERNATE.
When I go to bed at night, and my computer goes to sleep for a while, i don't know how long because I'm asleep, it will do odd things. When i wake up, my computer is turning on, then off, then on, and it keeps doing this over and over without any human interaction. When i unplug the power cord from the computer, then plug it back in, it works, sort of. When i turn it on after doing this, i get a black screen, but a restart will let me use my computer. It never does this unless its sleeping for a long time. Any problems?
A new power source
A new graphics card