Why is it that when ever i sleep my body shakes almost as if i am having a seizure, but i don't have any diagnosed seizure disorders?

See neurologist: How do you know you shake as if you were having a seizure while you sleep? Are you awakened? Are there any other symptoms when you awaken? Does your body tend to jerk just as you're FALLING asleep or just as you're WAKING up? Is that what you're meaning? Anybody observing you while asleep to describe what's up? If none of those questions apply then, best to see a neurologist for an examination.