There's a truly terrifying SF story from I think the 50s or even earlier about someone who experiences their whole life that way - it's worked out in great detail.

It's not told in order, of course, but the "cause" seems to be these alien mushrooms that the protagonist eats as a teenager, but the consequences percolate backward as well as forward to their whole life from birth to death.

This eternal but completely static situation was very well explained. I still feel sick thinking about it.