Isn’t it our minds still thinking while we are asleep?
I can’t think or remember…
EDIT: And why sometimes are our dreams longer then other times…and sometimes I mean they feel really long…
There are many concepts regarding exact causes of dreams. They vary from treating dreams as a side effect of reorganising information in brain that occurs during sleep (and therefore refusing to give any kind of importance) to seeing them as an insight into higher (spiritual) world [1]. Personally I would rather agree with the first option but not exactly. If dreams were needless, they would be soon eliminated by evolution. Since we are still dreaming, they must serve important purpose for our psychophysical condition.
The unusual longevity of dreams can depend on length of REM phase, when they occur. However, since in dreams the overall perception may be greatly altered, it’s perfectly possible to experience time flowing much slower than it does in reality.
Dreams can be interpreted as the subconcious thinking.
Unnecessary things like dreams are not phased out through evolution unless they pose a detriment to the organism.
Ok… 
well… …its all confusing stuff…but I think I understand, thanks.
REM sleep seems to be quite important. In the documentary “the secrets of sleep” they mention an experiment where they hook people up to an EEG and then when the see that they are entering REM sleep. they wake them up, so that they don’t get any REM sleep at all, or at least very little. What happened to them was that they started dreaming while awake. They concluded that REM sleep was given such a high priority that it forced it’s way into the waking state. In that light it doesn’t seem like an unnecessary function.
dreaming while awake?..wow im interested to know what thats like…you mean like extreme hallucenations? (sp?)
From what I remember at the moment, I didn’t get the impression they had EXTREME hallucinations. I did get the impression they had SOME hallucinations.