The 'sudden, brief, jerky, shock-like, involuntary movements' are called myoclonus (Fahn et. al. 1986). This brief twitching may involve a muscle or a group of muscles. When these jerky moments occur during sleep, the condition is called sleep myoclonus. Muscle twitches occur during the sleep stage that comes just before the person goes into deep sleep. It has been found that jerks due to this condition rarely disturb the person suffering from this disorder or their partners. It does not disturb sleep or cause the person to wake up. However, it indicates the risk of developing serious sleep disorders such as restless leg syndrome in the future. The condition affects fingers, toes, lips, and eyes, and therefore, is not noticeable to anyone who is watching the affected person sleep. Causes It is not a disease but a symptom which occurs during REM sleep, and is found to be stimulus-sensitive. This means that it is triggered by external stimulus like light, sound, or movement. Symptoms The symptoms are characterized by rapid contraction and relaxation of muscles. Some people may suffer from hiccups or hypic jerks when they are drifting off to sleep. A few individuals tend to suffer from jerks in an arm or leg, just before the person is drifting off to deep sleep. In some cases, the condition itself is a symptom of restless leg syndrome that needs medical attention. In Children You may feel your child is suddenly twisting in sleep. In most cases, both sides of the body are affected. A flexion of fingers, wrists, elbows, and sometimes feet is observed repeatedly while the child sleeps. To many concerned parents, it may appear as a myoclonic seizure attack or an infantile spasm. However, it is generally harmless in children. Benign Neonatal Sleep Myoclonus Coulter and Allen first described this disease in 1982. This disorder is also commonly mistaken as seizures in newborns. The symptoms include sudden, lightninglike jerks of the extremities during sleep. As the central nervous system matures in a newborn, it tends to diminish with time. Treatment In most cases, there is no treatment required. This condition rarely causes any problems to the individual and does not affect sleep. The condition is tested in children for any underlying neurological disorder. If there is no cause of concern, no treatment is offered. In case of benign neonatal sleep myoclonus, no medication is necessary to treat this condition. Adults and children need to be tested for any neurological abnormalities. When parents find their children jerking while asleep, they become worried that it may be a seizure. However, this condition may not always indicate any neurological injury or abnormalities. To be on the safer side, always consult your healthcare provider for more details regarding this condition and its clinical manifestations. Disclaimer: This Buzzle article is for informative purposes only, and should not be used as a replacement for expert medical advice.