Here’s the situation:
I was in a daydream, and within the situation I was daydreaming of in my head I committed a grave sin with full knowledge and consent. (sorry if that’s not a great explanation…I don’t know how else to describe it now…)
Would that be a mortal sin?
I don’t think so since according to Edwin Healy SJ, “'Full advertence means the attention that a businessman would give to an important business deal. Hence actions performed when one is half asleep,** in a daydream**, or half distracted would not be classified in this category.”