Sometimes when i am falling asleep, right before i get to sleep my body jerks violently as if i trip and fall & hit something. Ive talked to some of my friends about it and they experiance the same sensation as well. Have any of you had this happen, and if anyone knows what it is could you post an explination? Thank you.
Well it’s been discussed before on the forum, but I can’t find the post, so I’ll repeat what I wrote, then 
Science is not absolutely sure why it happens, but a theory is that it’s because of the falling sensation, and the jerking is a primitive reflex to this sensation. If it is true, then this reflex must have comed from the reptiles, because they have a reflex of strecthing out their arms and legs when falling.
The teory I came with, is from a scientific magazine I read once. But I don’t have excatly the issue where I read it, so I can’t make any reference to it 
The other thread is at…
slagt.net/ld4all/viewtopic.php?t=311
Edit: Oops, no that’s wrong… Try slagt.net/ld4all/viewtopic.php?t=417
Auugh, I hate when that happens!! Here’s an explanation from “Why Do Clocks Run Clockwise” by David Feldman (keep in mind that this was published in 1987):
"What are those twitches and jerks that occasionally wake us just as we are falling asleep?
"It has probably happened to you. You are nestled snugly under the covers. You aren’t quite asleep but you’re not quite awake. Just as your brain waves start to slow, and you fantasize about owning that Mercedes Benz convertible, you are jolted awake by an unaccountable spasm, usually in a leg.
"You have been a victim of what is called a ‘hypnic jerk,’ a phenomenon explained in David Bodanis’s marvelous The Body Book:
"‘They occur when nerve fibers leading to the leg, in a bundle nearly as thick as a pencil, suddenly fire in unison. Each tiny nerve in the bundle produces a harsh tightening of a tiny portion of muscle fiber that is linked to it down in the leg, and when they all fire together the leg twitches as a whole.’
“Sleep specialists haven’t pinned down what causes hypnic jerks or why they occur only at the onset of sleep. Although some people experience them more often than others, their appearance is unpredictable, unlike myoclonic jerks, spasms that occur at regular intervals during deep sleep.”
Ahh… Now I have a better idea of exactly what you are talking about. I was talking to a friend recently who is taking a course “The Biology of Psychology” and he was explaining this to me, that this sensation of jerking awake that is involuntary is normally because the motor cortex is shutting down. That is, control over your body is starting to be lost and because of that you get muscle spasms.
I thought they were called myoclonial jerks, or is that something else? I think it has been mentioned before about the falling sensation that sometimes happens and how it stems from when we used to sleep in trees (theoretically); I find that interesting.
Yeah, I am pretty sure that is the right term. The falling feeling is associated with the same thing, but I haven’t heard theories of why it exists (eg, you example of evolution), only how it exists and works.
Could it be that possibly you are entering the wrong period of sleep or are entering sleep much to quickly so your body reacts to correct the difference by jolting you awake? Or maybe its your spiritual body leaving your physical body but gets jerked back for some reason, maybe it comes in contact with some kind of barrier? I’m just pulling stuff out of my hat here.
I get those things all the time! I can be sleeping for hours already, and suddenly I’ll just jump. Like my whole body just shakes real quick. Then I look around, feel confused, and go back to sleep. Weird stuff…
Myoclonial jerk sounds like some sort of scientific insult.
Is the falling sensation like this: when you are half asleep , falling asleep, you are all of a sudden knocked back wide awake with a feeling as if you tripped and fell, or hit something, or something…yeh, something (hehe) and your heart beats fast for a few seconds…
ive had that a lot
i think it is when your astral body is leaving the physical body to go to the “dream world” and for some reason it gets pulled or pushed back in.
thats my opinion 
You’ve hit it square on the nose, thats exactly what its like.