In addition to what you’ve listed, the only intervention that seemed to have worked for me was blackout curtains (or otherwise making the room as dark as possible). It appears that light hitting your skin anywhere (not just your eyes) can reset your sleep cycle.
I’ve also tried, without any effect, melatonin, both in regular form (3mg pills), and immediate + sustained release (10mg), and transdermal magnesium oil (which one somewhat famous sleep coach swears by - see my summary of his video).
For comparison, here’s my deep sleep situation for the past week, measured with the Emfit QS:
If there’s a correlation between deep sleep and how I function the next day, it beats me. On Sunday, I was groggy the whole day, despite a sleep score of 90 and 17% deep sleep. The day before I was sharp, motivated and alert, despite a sleep score of only 70, and 12% deep sleep. Today I’ve been doing well, with 16% deep sleep. No exercise since ~10 days ago due to an injury.
Have to say that after 6 years of QS, I still haven’t figured out this sleep thing… my best hypothesis is that there’s an action-at-a-distance mechanism at play, in that I pay for a suboptimal night not necessarily the day after, but two or three days after. Or other factors (good luck controlling for them) play a much more important role. It’s been 20+ years since I remember waking up fresh, alert, and “ready to take on the world!!1”, as claimed in various sleep improvement programs I’ve seen. Maybe I need to try going vegan for a month.