Do dreams mean anything?

So i'm sat wondering "Do dreams mean anything?" - that's a interrogative sentence may I add. (English revision is kind of taking over my brain right now so excuse the random out bursts of analyse) anyhow back to answering my question. So dreams resemble our thought processes, they are a way for our brain to make sense of our thoughts, almost like a filing system. Last night I had a dream about a friend who I had seen that day but my dream soon turned into a 'nightmare'. I was challenged to cross a long bridge; below this bridge there were train tracks and at the middle of the bridge it was broken leaving a massive jump from one side to the other. If you fell the chances were you'd be dead. So in my dream/nightmare I followed three of my friends across this bridge until I reached this part - the jump. I couldn't do it so I turned away but now suddenly what was a bridge was just handle bars made from a tree, I slipped and almost fell but managed to pick myself back up, once I reached the safe land I started to hallucinate, in my dream which sounds kind of crazy, it was almost as if I was having flash backs as well, I was seeing things in my dream which no one else was. My dads friend appeared who passed away a couple years ago, he was just there floating staring at me with a blank expression on his face. Then someone else appeared but I can't remember who it was as the image in my head is quite vague. What did all of this mean? I understood my friend was in the dream as I had saw him that day, but why the broken bridge and the train tracks? Why Leigh? Why the weird hallucinations and flash backs - this is what I don't understand. Something makes me think it is related to how i'm feeling, that I want to cross this bridge (revise & pass my exams) I want to succeed but there is something stopping me and I feel there is nothing I can do about it, accept turn around and give up; but as I'm trying to give up there is something stopping me, telling me I can't and I won't. So are dreams just the imagery of our minds? Do they represent our emotions?