My child upper lips bleeding only at night, and it looks like theres a cut in the middle of his upper lips. soon he woken up blood stain on his teeth?

Common enough: Tearing of frenulum ( midline attachment of upper lip to gum margin) tears relatively easily when a child falls & hurts his mouth or face. This may lead to an initial burst of blood which quickly stops or sometimes may ooze for a while. He must have had that so when he woke up he had some staining of his teeth with blood. If this is happening frequently u shd have him checked right away.