Roxie - I've had that happen as well. I know how scary and unnerving it can be!!!
I've had sooo many of the 'sleep jerks'! I've had three black eyes that I've given to myself, and the dogs and hubby started all sleeping on the far side of the bed when that was happening!
snicker, snicker!!
The worst are the full body jerks - which happened randomly for me, not just while I was going to sleep or coming out of sleep - although mainly I had random limb/toe/finger jerks frequently during the day. I had one muscle under my right eye and one muscle on the top eyelid of my right eye that stuck around the longest. Irritating as all get out!!!, but they went away with as my Lyme treatment progressed.
When they were the most active, my muscles would even tired considerably, so I would do the full body detox soaks and they would ease that discomfort.