PROOF OF HEAVEN

I started reading "Proof of Heaven" last night. It's a true story about a neurosurgeon who dies for a period of time and claims that he visited heaven and he can prove it. It's pretty interesting so far, and I'll finish the book but already I am skeptical since he's in a coma. A coma isn't dead..and so it seems to me anything that occurs while you're in a coma is brain activity and not neccessarily afterlife. Right? Maybe he'll convince me. I'll let you know.