The Lazarus Symptom

15 year old Lenville has a question. Readers are invited to answer.

In the year 1244, at age 29, King Louis IX of France "died" of plague. During his funeral ceremony, to everyone's horror, he sat up in his coffin. He lived for another 26 years. Similar incidents take place even now where people look like they are dead but are actually still alive. What is the viewpoint of scientists as well as the Catholic Church on this particular symptom?