What kind of functions sleeping & dreaming provide?

There's few parts of you which may require sleeping: brain & body. Your body needs sleep, because physically it needs the ways relax to longer than you can afford yourself relaxing during the day. Plus mechanisms employed during the sleeping can help them relax the way you would never relax yourself by your own efforts.

Your brain needs sleep, because the neurons needs rebooting. During the day brain exploits different maps of neurons depending on the way of thinking you choose and depending on the activities you perform during the day. For average human there's a hundred maps available within neuron networks. During the day you choose around 3 to 7 of them to apply to your situations during the day. The fact that you're not using hundreds of other maps at the moment is cruicial: you know the rule - if you don't use the information in your brain, it gets restructurized or worse: it gets deleted totally. That's why sleep is important - here comes another God's invention called "dreaming".


Dreaming 

This picture aren't representing the truth: the longest part of the neuron is axon which is so long that it wouldn't be possible to take a picture on nano-camera or to represent it within the range of reasonable even imaginable picture.

Dreaming exploits the most important parts of neurons - the essential ones. Brain can't delete the information without your permission. What is a permission? It is your psychological comfort - in other words brain always cares about your psychics: it deletes the information which may harm your perception, and it restores the information loosing which also may harm your ability to perceive world quietly (without psychological breakthroughs). Dreams helping brain to find those connections between your psychology & between existing connections. That's why its so useful to remember your emotions - because they're helping in exploiting your brain more efficiently during the nights.

While brain keeps performing its emotional maintenance functions during the night, it should maintain the whole rebooting process, that's where sleeping mode for neurons brought to action. When you're dreaming you may find out that the dreams which you see during the sleep showing you details of memories which you would never remind yourself consciously. Also during the sleep you find out that your memories are organized the way you would never organize it that way - they has logical order, there's even more logic than sometimes you may think about your conscious analysis.

When you dream two particular things happen to your neuron network maps:
1. Neuron networks keeps doing background restructurizing processes which also takes time
2. As part of restructuizing process your neurons are killing old processes. Humans has tendency to get obsessed with things they do. Of course it may be important to analyze important things over and over again, but brain also must keep doing its job: architect of brain understood, that without switching activities, you won't get the maximum potential of your brain - because when you learn two similar subjects, you starting to compare them, and that's beginning of the process where brains are best: in connection/junction points perfection. That's the analytics machine which looks like boiling room - you put a lots of things in your huge pot of soup, then you try its taste and learn to prepare more and more dishes within your capabilities.

What is subconsciousness
People get used to think about subconsciousness as about incredible valve where you can store whatever you want. Its not true. I do believe in limited brain structure about past. Power of brains are logical & mathematically explainable powers. E.g. when you're trying to remember some event which you already forgot, here comes mathematics when brain is trying to compare outputs from its neurons in order to understand whether some things are true and some things are lie.

While if you would had the access to your subconsciousness it would give you access to huge range of information, its still doesn't guarantee you that you'll remember everything you want. Brain experts use the world "subconsciousness" only to describe the background processes happening during thinking process. The background processes are important: they are the ones which make possible thinking itself: even the thinking itself are background process, because when you recognize someone's face - you don't understand how does it happened, you just understand that here's two faces and you can compare them - without knowing how you do it.