This is something I have had a lot of over the last six or seven years but I never see anyone discuss it so I wanted to see if it is common in anxiety sufferers.
Myclonic jerks are when a muscle or group of muscles contract involuntarily, so when they happen, a shoulder may leap forward, or an arm fly out, or your hand start twitching like mad. I often get myclonic jerks in my lower back which causes my body to arch forwards and my arms to fly back.
I get it throughout the day whenever my muscles are given a chance to relax, and particularly at night when I'm trying to go to sleep. It doesn't actually bother me because I often find the movement temporarily relieves tension in my body and gives me a brief feeling of satisfaction - like when you stretch, you know what I mean? It's a nice feeling. But it doesn't half bother everybody else! It always makes my boyfriend jump out of his skin because one moment I'll just be lying there nice and relaxed, the next my body will suddenly leap into the air!