Dreams & TVs

This theory that i am about to share with you is probably one of the most interesting theories that I have ever heard. I stumbled upon it while readong the book "Killing Yourself To Live: 85% of a True Story". I hope you enjoy this as profoundly as I did.

Here is my question. Have you ever had a dream that lasted a long time, like 100 years? But in reality, most dreams typically only last 20 minutes. So here's the question, how does our head know how to skip through many years, but in reality it was only 20 minutes? Is it that TV has tought us how to skip through time in our heads? Because if we were watching a TV show and it was the middle of the day and then theres a commercial and it's night time, our brains automatically understand that we have skipped hours ahead into the future without even thinking. Just like that. But what about when there was no TV, there were books, which also perpetuate the same sensation (and it follows the same basic principle), but what about before books, how did those people dream? Were those dreams only in the time-frame of 20 minutes, or did they know how to skip through time in their heads like we do now?

This theory strikes me as simple as it can be, and yet without even knowing it, this is true. How did we learn that we could skip through time in our heads?