Mortals are relatively ignorant of the supernatural world, a fact that increases the danger of Paradox for wielders of dynamic magic. While some mages look down on Sleepers, most wish to protect them and help them Awaken.
The reason for the Sleep varies in both games:
In Ascension, their internal Avatar has not Awakened, so they are still complicit to the Consensus, unable to think beyond that to which everyone agreed.
In Awakening, they are afflicted by the Quiescence, a shard of the Abyss within the human soul that prevents them from realizing the Truths of the Supernal World.