interesting article, makes sense and the tunnel sensation I have always thought is simply your sight failing one final time and not some imaginary pathway into heaven (or hell for you naughty people).
As said above I think once you're done, you're done there is no afterlife or heaven & hell. I thought I would believe in it as I love reading up on the Egyptians whose race is one that believed in afterlife more strongly than most any other civilisation, they went to great measures to make sure they were cattered for in the afterlife. Even workers and those not so lucky in life (like the Pharoahs) would spend the moments away from the enduring labour of work on their own burial chambers, creating a world fit for the next life.
I do not pity them or even think they're wrong to have done that, that is what they believe I just don't which is why I suppose I find them such an intriguing civilisation to read up on.
When you see that tunnel, basically you're thoroughly ****ed, it's you final chance to say goodbye as once that tunnel gets smaller and smaller and thus turns into darkness you're gone, not even purgatory will meet your gaze as you can gaze no more.
Job done, hope you lived your life to the fullest, RIP.