So when I go to sleep normally (Lie on my side) I do not twitch at all but when I lie on my back as i was trying to do a wake back to bed after like 10 minutes and I started getting really relaxed and started to feel like i was spinning then I started twitching like in my lower back I do not know if it because I take Metaxalone for shoulder injury but Whenever I get into the point where I am like spinning I always twitch in my lower back.