This is somewhat conjecture, but bloodwork indicates that my pituitary gland completely shut down at the beginning of 2018, following multiple viral infections and a year of intense triathlon training. My hormone levels were just completely out of whack. I've been getting shots from my endocrinologist, and a week and a half later, I'm feeling like a different person. Hopefully I just need it temporarily as a kick-start, and can then wean off.
Otherwise, my sleep habits are functionally pretty close to perfect.
* No food or blue light after 6pm
* I only use my bed for sleep (no reading)
* No caffeine of any kind after noon
* Black-out curtains
* In bed by 9pm
Falling asleep and staying asleep has never been an issue for me; it's just getting good sleep that's been the problem.