How this possible if your body is lockdown in REM sleep?

dreams happen throughout sleep. the deeper into sleep you get, the more vivid, realistic, and memorable your dreams become. sleep walking/talking happens when youre acting out tendencies in your dreams, and usually happen in stage 4, right before stage 5 REM sleep. this is also the case with night terrors, where people sometimes cause harm to others or scream because they are having such a horrible dream (if they are trying to fend of a killer in their dream they might actually be hitting and punching a person in real life).