I sometimes jump in my sleep causing the muscles to contract in my arms. Can this jumping issue cause a loss of muscle mass?

No it is usually- -due 2 Ur being close 2 Bng awake & sleep,. Ur muscles relax in sleep so U do not act out Ur dreams. U jerk because U awaken & Ur muscles tonight up 2 their normal tone. In sleep ur body is essentially paralyzed by the brain, people who R not, is an example of a true sleep walker, who does not recall the events or why he awoke where he is. .