Is having many myoclonic jerks every night normal?

Yes: Myoclonic jerks are involuntary twitching episodes of muscles or groups of muscles. They are very common and almost always not an issue. A common time for them to occur is at night, and often while falling asleep. However, if other symptoms exist or this condition is changing it can be a sign of some nervous system problems, too, although rarely is myoclonus the first sign.