Sleep myoclonus occurs during the initial phases of sleep, especially at the moment of dropping off to sleep, and include familiar examples of myoclonus such as the hypnic jerk. Some forms appear to be stimulus-sensitive. Some people with sleep myoclonus are rarely troubled by it, or need treatment. If it is a symptom of more complex and disturbing sleep disorders, such as restless legs syndrome, it may require medical treatment. Myoclonus can be associated with patients with Tourette syndrome. Signs and symptoms
Myoclonic seizure can be described as "jumps" or "jolts" experienced in a single extremity or even the entire body. The feeling experienced by the individual is described as uncontrollable jolts common to receiving a mild electric shock. The sudden jerks and twitching of the body can often be so severe that it can cause a small child to fall. A myoclonic seizure (myo "muscle", clonic "jerk") is a sudden involuntary contraction of muscle groups. The muscle jerks consist of symmetric, mostly generalized jerks, localized in the arms and in the shoulders and also simultaneously with a head nod; both the arms may fling out together and simultaneously a head nod may occur. Symptoms have some variability amongst subjects. Sometimes the entire body may jerk, just like a startle response. As is the case with all generalised seizures, the patient is not conscious during the event but the seizure is so brief that the person appears to remain fully conscious.
Identifying whether or not abnormalities in these pathways cause myoclonus may help in efforts to develop drug treatments and diagnostic tests. Determining the extent that genetics play in these abnormalities may lead to potential treatments for their reversal, potentially correcting the loss of inhibition while enhancing mechanisms in the body that would compensate for their effects. Etymology
The word myoclonus uses combining forms of myo- and clonus, indicating muscle contraction dysfunction. It is pronounced  or . The prevalence of the variants shows division between American English and British English. The variant stressing the -oc- syllable is the only pronunciation given in a half dozen major American dictionaries (medical and general). The variant stressing the -clo- syllable is given in the British English module of Oxford Dictionaries online but not in the American English module. See also
Periodic limb movement disorder
Benign fasciculation syndrome
Restless legs syndrome
Fasciculation
Brain Zaps (SSRI withdrawal)
Clonus
Fahrs syndrome

References
External links

The first version of this article was adapted from the public domain NINDS Myoclonus Information Page. "Why do we twitch while falling asleep?" (The Straight Dope)
Myoclonus Fact Sheet,  National Institute of Neurological Disorders and Stroke (viewed 5 Apr 2005)