Excellent piece, Robert. Well researched, with good takeaways. Particularly, I can attest to this finding:

Lack of evidence for effectiveness on insomnia: "Research on whether melatonin supplements help people with chronic insomnia points to a lack of effectiveness. A 2017 review of studies on melatonin, often cited by experts in the field, concluded that it should not be prescribed for chronic insomnia".

Having developed chronic insomnia from my first career — due to several nights and early mornings in the hospital — I found melatonin totally ineffective to get me back on "normal" circadian rhythm.

Your 4 important remedies for poor sleep are spot on.