Sleep

I want to know why we dream. It has nothing relevant with what I did in the previous day. So where is my brain getting this stuff?
And sleep is weird, you lay around waiting for it to happen. You don't know when it does happen and then the night feels like it was 2 seconds and then, you just wake up. When you have a hard time falling asleep, but you feel really tired, if you're so tired why isn't your body going to sleep? Why do our eyes move really fast when we fall asleep? I heard that there is a part during your sleep when your eyes start moving back and forth really fast. I thought sleep was for rest? What are our eyes looking at? Where do we go? Does our brain trick our body into believing we are somewhere else? I've also heard, that when you think about doing something, like running or tensing up your body; that your body tensing the muscles that you would use to do whatever  you are thinking of, very slightly. I heard it's because since you are thinking of it, your body cannot comprehend the difference between a thought, and actually doing it. Why is our body unable to understand the difference from a thought and actually doing it?
I wish I could go to one of those places where they like monitor brains, and sleep. So I can get all kinds of crazy answers. ugh, the brain is so creepy!!