#most horrifying experience--- do you ever wakeup at night and can't move???

I was distraught until i came to know the reason behind that horrid experience which made me afraid to the darkness. Dusk was frightening to me and at night all horrible scene started flashing in my mind which i have ever seen in the horror movies. Problem was becoming serious and many nights i couldn't even sleep. but a little research of mine helped me a lot. And now i am completely fine and all that spooky experience has gone far.
but the question still remains and lets look at the facts in brief;

A good sleep depends on a lot of factors than we generally know about. many people like me experience the problem of suddenly waking up in middle of the night but being unable to do anything.
There are many theories like; What is the good time to sleep? What to eat before sleep sleep to get a relaxed good night sleep? or What must be the position to get a better sleep?
But the are hardly any theory about the bizarre things related to sleep.

THIS IS WHAT HAPPENS;

i read somewhere that various social and psychological factors influence sleep. and such frightening experience is named as Sleep Paralysis. and several studies have shown that most of the people it includes are students who have a disrupted sleep pattern and people with mental disorder like anxiety and depression.

But if we woke up and our brain is awake, how can the body not move??

There is stage named as REM sleep and REM stands for rapid eye movement. we dream through many stages but the dream experienced in REM sleep appear to be more real. such as the dreams where you feel like you are falling somewhere, they are realistic ,aren't they?? The brain is highly active in this sleep and many believe that the body is not able to act as well. which is called REM antonia.
but this effect however last a few minute or seconds.

And the people who are depressed or sad feels some kind of a presence around too.

AND there are different type of sleep paralysis;

FIRST > People feel intense pressure on the chest and they feel they can not breath. And thats what i have experienced too. This happens mainly because they are scared.

SECOND > This sleep paralysis gives the feeling of a presence , fear, and visual and auditory hallucinations. Even a slight sound can give you the fright of your life.

THIRD > Some people feels like they are levitating or flying around the room. This type of sleep paralysis is different because different areas of the brain are active at the time the person is half sleeping.

However , prevention is difficult about sleep paralysis. but the day i came to know the facts about this problem, its all gone away. because now i know that there is nothing to get scared as there is no ghost is my room, lol...
Has this ever happened to you?????? What are your experience???