I've only got my experience with sleep deprivation and the methods I use to fix it. I had severe sleep deprivation and now I sleep 8 hours on average, with quality sleep.
I am a very light sleeper, on top of having problems falling asleep. This is what I did:
1) limiting the noise - I installed new windows and added new door that leads to my bedroom; I have a fan that I put next to me, put it on the highest speed and it absorbs any noise left. You can achieve this with a "white noise app", too.
2) completely dark room - I cover the windows outside, and then inside too (just in case any light escapes).
3) I fit my meals within 8 or 9 window as a part of TRE (Time-Restricted Eating) - my first meal is around 9AM. It does not have to be perfectly accurate (8:45, 9:15 acceptable)
4) strength training every day (assuming you are cardiovascularly fit); I do sprints as well (twice a week or so)
5) zero alcohol - it is one of the strongest REM suppressors
6) zero caffeine - very important. The average half-life of caffeine is 6 hours. That means that after 6 hours, you still have 50% caffeine in your body.
7) write down the following, and try to look at them from time to time: when you eat, what you eat, calories/macros breakdown, when you go to bed, when you fall asleep (approximately), when you wake-up, and a summary of the previous afternoon and night time - what you think is the reason for the sleep (or lack of) on the day of
8) try to fit in with your circadian rhythm. On average: we are at our peak 10AM-3PM - try to fit strenuous activities in this period (including heavy strength training - since I am a remote developer, I can do this).
9) I walk around 8-10 km every day, part of it in the morning, part of it around 20:00
10) try to limit blue light at night - some ideas: dim lights, orange/red glasses filter, orange/red light bulbs.
----- These were the major things that I did, and some combination of them seem to work. I don't know which ones precisely. Some things that didn't work for me:
1) some natural remedies like valerian tea, etc. - it made me worse, actually. 2) meditation - just doesn't work (for me). A lot of people swear by it.. 3) nothing of this sort: https://www.artofmanliness.com/articles/fall-asleep-fast/
Try to learn something from what you eat - but be brutally honest with yourself and write down everything that contains calories that you eat. I noticed that I sleep worse on the day I eat more sugars (and I hardly eat sugar at all!).
Hope this helps someone.. I know how hard it is without sleep.