In the following video, Paul Robinson shows the nearly mirror image peak of cortisol and T3 during the early hours of the morning. The theory is that the reason some struggle with low cortisol in the morning and afternoon is because their adrenal glands don't have adequate t3 during this time. The solution is to take t3 1.5 to 2 hours before you wake up. You set an alarm, take a small dose of t3 then go back to sleep. This is supposed to work better than even supplemental hydrocortisone at achieving optimal cortisol levels and repairing the adrenal glands. For more information, google CT3M for circadian t3 method. It's been known that adrenal dysfunction causes hypothyroidism. But it could be that hypothyroidism causes adrenal dysfunction, which causes even worse hypothyroidism which causes even worse adrenal dysfunction, etc.