My husband has this problem..the neuro told us it is often part of the Parkinsons symptoms.
Normally a person is paralysed when dreaming but this process stops in PWP and they act out dreams.
He prescribed Clonazepam but it made my husband very drowsy the next day So he stopped it.
We now sleep in separate bedrooms.
He knows nothing of the threshing around, punching and shouting and now I don't either!