Too much cortisol can disrupt sleep. Have u tried ashwagandha? It's part of Buhner's protocol, u can take it before bed and will lower your cortisol spikes during sleep.
This is really helping, there is a double blind placebo controlled study about
it
www.ncbi.nlm.nih.gov/pubmed/23439798"The treatment group that was given the high-concentration full-spectrum Ashwagandha root extract exhibited a significant reduction (P<0.0001) in scores on all the stress-assessment scales on Day 60, relative to the placebo group. The serum cortisol levels were substantially reduced (P=0.0006) in the Ashwagandha group, relative to the placebo group. The adverse effects were mild in nature and were comparable in both the groups. No serious adverse events were reported."
Just watch out for the dosage, use Buhner's recommendations, 1 gram of full herb (not the extract), but not much more. I used a NOW 500mg extract 1:10 that was very helpful in the beginning but then has put me in hyper-thyroid mode.