Sometimes people fall asleep without making the nightly rounds to turn out lights, close windows and lock doors. Sometimes they fall asleep before all of the little ones are safely tucked in bed. Sometimes people are so sound asleep that they are very hard to wake up.
Maybe they wake up and can't remember how they ended up in bed at all. Maybe they find other things amiss and they have to lie to explain it because they are too embarassed to admit that they just don't remember.
If this happened to a person, she would probably be very emotional, confused, maybe even prone to cry. She would probably be scared to death to believe that she might have done something unthinkable. There would be gaps in time which she could not explain.
Blackouts can be caused by prescription drugs, alcohol or combination of the two. I think that this is one possible scenerio which would fit the story we are getting.
JMO