Why do i jerk when im about to fall asleep?

It is called nocturnal myoclonus which is a sleep disorder where the patient moves limbs involuntarily during sleep and has symptoms or problems related to the movement. If the patient moves limbs during sleep but there are no consequences, it is simply called periodic limb movements of sleep (PLMS). PLMS can range from a small amount of movement in the ankles and toes, to wild flailing of all four limbs. These movements, which are more common in the legs than arms, occur for between 0.5 and 5 seconds, recurring at intervals of 5 to 90 seconds. A formal diagnosis of PLMS requires three periods during the night, lasting from a few minutes to an hour or more, each containing at least 30 movements followed by partial arousal or awakening.

PLMS can cause insomnia and daytime sleepiness. The incidence of this disorder increases with age. PLMS is related to restless leg syndrome (RLS) in that 80% of people with RLS also have PLMS. However, most people with PLMS do not experience RLS. PLMS has made its way into popular culture, being referred to as "jimmy legs" and "jimmy arms" in an episode of Seinfeld, and has been known to cause couples to sleep in separate beds. Nocturnal myoclonus is treated by medications aimed at reducing or eliminating the leg jerks or the arousals. Non-ergot derived dopaminergic drugs (pramipexole and ropinirole) are preferred. Other dopaminergic agents such as co-careldopa, co-beneldopa, pergolide, or lisuride may also be used. These drugs decrease or eliminate both the leg jerks and the arousals. These medications are also successful for the treatment of RLS restless leg syndrome.

I've always wondered that to. It's like right when you fall asleep everything that you hear gets louder and one little sound scares the crap outta ya and you jerk! It's scary sometimes. Like I fell outta my bed one time cuz i got so scared!

I do that sometimes, but it's usually when I'm trying to stay awake. It's almost like part of my brain realizes I've fallen asleep and says "OH CRAP" and I jerk awake. Doesn't happen in the middle of the night.

I've always wondered that to. It's like right when you fall asleep everything that you hear gets louder and one little sound scares the crap outta ya and you jerk! It's scary sometimes. Like I fell outta my bed one time cuz i got so scared!

OMG...I THOUGHT I WAS THE ONLY ONE!!!! SOUNDS LIKE SOMEBODY SLAMMED A PALLET!