Now for dreams ending so fast when you come to realization, this could be because its the end of your rem period. Now the black is a state where your not too awake and when your not too asleep its like one foot in the dream world and another foot in your waking life. "The black" almost always leads you to another dream and they are more likely to be false awakenings so when you go through this black stage as soon as you "wake up" reality check.