Myoclonus and extreme movement

When you lay down and relax and then upper body sits up and you make snarling sounds and your face changes like a mad dog is this part of myoclonus?

[CCF-Neuro-M.D.-PW]

Myoclonus is a rapid jerk of a body part which is abrupt and irregular

Proprioceptive myoclonus is a more generalized axial (the midline) jerk that results from an irritative lesion in the spinal cord

However, by your description, it is impossible to tell if this is the case. If you are concerned you should make an appointment with a neurologists in your area

Good luck