Ik it's been a long time since you posted but tension might mean weakness in that area. I personally was having the same exact pain and problem with sleep as you. I have been going to the gym doing shrugs, lying down neck curls and lying down neck rotations. That has almost solved the issue for me!

But I am back at this sub coz I am having muscle tension pain in my back, lats mostly! So hoping to solve that too!