I was on Cymbalta was up to 120mg for 2yrs. no real sleeping issues until therapy starting poking at stick at my PTSD.
I had to switch to effexor and am just off cymbalta 2 weeks now.
I can't help but wonder if it is coincendental that your insomnia may be the PTSD kicking up. The C does help with pain over time, that is why I went to 120mg.
Here is a link to a trusted site. They have PTSD and Complex such as I have.
Find the list for your dx and see how many symptoms match. Then talk to your Doc about
the med, sleeping and PTSD if enough matchwww.ptsdsymptoms.org/ptsd-checklist.html
I wish you peace and comfort