I was dreaming that my  now 8 month old daughter was 12 and was having a sleep over at our place.  I was so tired (been sick and over-worked lately) that in the dream I was sleepy and went to sleep!  I was dreaming, and in this dream I went to sleep.  What happened then?  Total black out. 

This was between snoozes on my alarm clock.  So I woke up from a complete nothingness of mental state 10 minutes later as the snooze went off again.  This has not happened to me before, that I can recall.  When I calm my thoughts and go over the dream again, I get a split second of very deep vibrant blackness that almost has a negative shine to it.. hard to explain; but only for a split second then there is no memory.

Sounds you really had a sleep deprivation. Too less sleep for a while, and sleep will get you quite forcefully, like falling into that blackness even in a short alarm-clock snooze period.

Spooky