Welcome to HEALTHCARE MAGIC..
As per your complain bleeding from tongue post trauma is not an abnormal finding and is due to rupture of small blood vessels due to trauma with the tooth..
In case if the bleeding is continues it needs immediate medical attention and if the cut on the tongue there is a possibility that the doctor needs to put stitches to initiate healing and cessation of bleeding..
In case if while sleeping the mouth of your son is pooling with blood you should take care as it can cause choking
and breathing difficulty and also aspiration of blood into respiratory passage which can be fatal..
You should make him sleep reclined laterally..
Take him to a Pedodontist or an Oral Surgeon immediately so that he can access the situation and treat accordingly..
As of now you can take a sterile gauge piece and apply moderate pressure over the bleeding area to reduce bleeding.Cold
compresses will also help in cessation of bleeding..
Hope this information helps..
Thanks and regards..
Dr.Honey Nandwani Arora.