I believe that coma is a form of refuge when things become too heavy to bear but when it is still too soon to die, because emotional accounts have not yet been settled. I've often had the impression that those in a coma were giving the people around them time to prepare for the ultimate separation. Some of them are waiting for a particular visit, or a reconciliation that has not yet taken place.

Marie de Hennezel, Intimate Death by Marie de Hennezel, Carol Brown Janeway, translator