Hey! I worked in (ground based) EMS myself for half a decade. Was a fun time but at times fatigue sets in and strikes you from behind. What worked best for me was a two week vacation when I felt fatigue sets in. Just get out of all this. I mean out-out: mountains, sea, bush, go hiking, fishing, biking - whatever works. And of course work-out in between. That should put you to sleep fairly quick
Another trick: Try to make use of your natural sleep cycles. Each cycle is approximately 90 minutes. Try to sleep multiples of 90 minutes (e.g. 6h, 7.5h, 9h...). It makes it way easier to get up in the morning because your alarm clock doesn't get you out of the deepest sleep (if I had to get up in only 5hrs I'd even rather skip 20minutes of sleep before I went to bed to get up after 4.5hrs but be fully awake).
That proved extremely helpful to me over the time.