One of the nine elements that generally occur during NDEs is the tunnel experience. This involves being drawn into darkness through a tunnel, at an extremely high speed, until reaching a realm of radiant golden-white light. Also, although they sometimes report feeling scared, they do not sense that they were on the way to hell or that they fell into it. Instead of a tunnel, some people report rising suddenly into the heavens and seeing the earth and the celestial sphere as they would be seen by astronauts in space. Once on the other side of the tunnel, or after they have risen into the heavens, the dying meet people who glow with an inner light. Often they find that friends and relatives who have already died are there to greet them. (Dr. Raymond Moody)

Here is an interesting link:
http://www.near-death.com/experiences/research16.html
Some people say, a newborn remembers its birth, and stores the memory until death. As the baby travels down the canal, it sees light at the end. When the person dies, it remembers the light at birth, explaining the tunnel of light. But, wait, babies don't open there eyes until a few days.:)

I fainted from blood loss once. (hemorrhaging from a miscarriage)
The blackeness creeped in from the outer regions of my field of view & closed in. I think that's where people's recollections of a 'tunnel' come from.
Scared the bejeesus out of me. Then I fainted again. :(
I thought I was going to die & I just wanted more than anything for my kids & my husband to be there.
With thoughts like that it's not hard to see how people would visualize loved ones at their sides.

That's my personal take on it anyways.

One of the nine elements that generally occur during NDEs is the tunnel experience. This involves being drawn into darkness through a tunnel, at an extremely high speed, until reaching a realm of radiant golden-white light.
They say that in other cultures where Heaven or it's equivlent is described as a city, people in NDE see tall buidlings. It's probably a mental reaction to the situation like a dream state would be my guess.



babies don't open there eyes until a few days.:)
Only if you're a puppy or something. :p
Humans are born with their eyes open.