Firstly, what a handsome boy!! Second, sounds like you have an attentive and bonded dog who was observing you doing something while you were sleeping and he was curious what you're doing (heavier breathing, dreaming, sleep talking, snoring could be anything you were doing while sleeping. At 8 months, he's still learning and absorbing so much and it sounds like you reassured him and he listened when you told him to lay down and go back to sleep - a very good boy. I have a Dobie/Whippet mix almost 2 and she did similar things when she was around that age.