How long do you dream your entire life?

It varies. We sleep on average 1/3 of our lives, but not all of that is spent in the R.E.M. sleep state. On average the R.E.M. sleep state takes up 20-25% of a healthy adults sleep cycle in an 8 hour night of sleep, but certain factors will increase or decrease the time spent in R.E.M. If you wake up in the middle of the night it takes your body longer to return to R.E.M. than if you had stayed asleep. Conversely staying asleep for longer than 8 hours will cause R.E.M. sleep periods to last longer, increasing the total time spent in the R.E.M. state.

There is no possible definite answer to this question