To all who have this problem----
What to test? TSH thyroid stimulating hormone, Free T3 and T4, Total T3 and T4. The TSH should be under 1.5 and the other values should be at least 50% with the desirable level 75-90%. Insist on all these tests as a TSH can be deceptively high while the other values are in the pits. Doctors will incorrectly try to use only the TSH.
NEW INFO, This is the NORMAL function, yes?

Is "kicked off" Cortisol @ 3AM a spike? Or gradual? Had this decades before ANY meds. Been to sleep study, learned the logs etc. After the first REM cycle (around 4am, never later than 5) I hear every car pass on the road etc. then tedious waits for patches of sleep - rinse repeat. Now I know why CBT was useless (for me).
Cortisol & PTSD are old news, this is first I've heard of the Thyroids role. Will get new Pcp (np) to run 24 hr cortisol.
For years I been on 'em over Thyroid (85% textbook Sx of Hashimoto). All the Free & total T's, "low range" TSH a "bit elevated" - probably due to ineffective Thyroid UPTAKE (or excess dumping)... Dr. SAW the Hashimoto, drew fasting labs 4x times a year, to catch a "T" under the "treatable line".
Finally, I brought him xerox from the library, and asked "Okay, doc - we HAVE the thryroid juice, let's go after what it's not doing the JOB." He said if we VERIFY a defect in Thyroid
activity, (despite present bio-markers) then he could treat it.
Don't recall names for Thyroid "transport & usage" bio-markers. Doc's wont draw lab for 'em unless we ask. (US, Medicare) private insurance might do better idk
One must demand (sadly) a full, detailed paper copy of labs; And interrogate provider rigorously on interpretation.
THANK YOU hothot

PS - So
how does the thyroid regulate cortisol? Even a link will help.