i read everywhere that dreaming is the last stage of 4 in the sleep cycle and you dont start dreaming till about 40-60 minutes after falling asleep… so how comes when i wake up in the morning and go back to bed for 30 minutes i dream right away? surly it cant be true… 
Every cycle (of 90 minutes) the last REM stage gets longer. It can be up to an hour at the end of the night.
During REM most people wake up (10-15 times each night), but we forget we do. It is just like when somebody talks to you in the middle of the night, you can’t recaal the conversation in the morning.
So, when you wake up during REM phase you can continue dreaming after you fall back into sleep. In the morning it is more likely to remember your wake-ups.
Beside that: it is also possible to dream in NREM (non-REM) sleep. 
ok, but how come we start dreaming again instantly? i fall back to sleep for 10 minutes and i dream for i think all 10… how come i dont need to go through all the stages again?
If you wake from REM for only a brief time, you continue where you left off… in REM
Rem nature is still unkown,so we dont really know “why”.But it seems to be somehow important for us cuz if you deprive yoursef of sleep for long enough you will start dreaming right off.
also, you may lose sense of time, so even if you dream for only 15 minutes, it can seem like 5 or 6 hours.
I think the whole process of “falling asleep” is still a big mystery.
If I get woken up after just minutes of sleep, I sometimes catch my thoughts drifting off into a dream. This is during my first sleep cycle for that day also, so I havn’t been to REM cycle yet … I think. These dreams however, seem to be “mini-dreams” and are the hardest for me to remember. But I remember some dreams that I’ve had just minutes after falling asleep.
Is this REM? If so, why so soon?
Is HI, or Hypnagogic Imagery, related to REM?
I tend to believe that you can dream the second your eyes close, it depends on how sleepy you are, and how long it takes for you to fall asleep. But I don’t think it takes 40 minutes to start to dream.
No, this is not REM.
It is not directly related. However, in both cases brainwaves are relatively high. (Close to consiousness). In later sleepcycles during the night (after waking up) you can experience hypnagogia before going back into REM sleep.
Recent studies show that REM sleep and dreams are two different systems.
We also dream in NREM sleep, but it seems that those dreams are somewhat harder to remember, possibly due to slower brainwaves.