In short, people used to go to sleep at sunset, get up after 3 or 4 hours, then socialize or spiritual time for a few more hours, go to sleep for another 3 or 4 hours and wake up at sunrise.
Nowadays, we usually knock out our sleep in one segment, wake up to an alarm clock and forget what we dreamt about.
We spend a third of our lives sleeping... might as well make the most of it! Check out my lucid dreaming page for more sleep tips! :)
more info here: http://www.collective-evolution.com/2014/10/02/your-ancestors-didnt-sleep-like-you-are-were-doing-it-wrong/