(Revelation 21:4) And he will wipe out every tear from their eyes, and death will be no more, neither will mourning nor outcry nor pain be anymore. The former things have passed away.”
My Nuerologist says this is normal to those who do not sleep well. It has a name, but I can not remember it.
It only means when our body starts to relax it jerks because we are not sleeping well when we sleep.
Hope this helps.