The Dread living in the depths woke up again as he felt that something was off recently. He felt an increasing amount of "Willpower" appearing in the air from time to time.
It had very sharp senses. It was able to feel and know everything that was happening in that cave from far away without too much effort.
The monster was sleeping for nearly a month, so a lot of things happened while he was unconscious. For a moment, he didn't even remember about the boy that fell inside that cave and whom the Dread was expecting to be his next meal in just some months.
As said before, it didn't have high expectations on Dean, although he could manage to survive until that point.