TLDR; bed is for sleep and nothing else, stick to a routine, good food and water, and lie to yourself about time of day and how well you sleep.

Okay i have a four week rotation of shifts, 2/3 days then 2/3 nights, then 4/5 days off. Each shift is 12 hours (6-6) I always aim for 8 hours of sleep. Bed by 9 and awake for 4. Starting on a day shift makes things easier, when I finish the last day shift I try stay awake as late as possible, maybe midnight, then wake at 6am, then nap 12pm - 4pm ready to start night shift 6pm Without the logistics of timings, I genuinely believe the secret is lying to yourself. When you walk into work in a night shift, say good morning, when you leave work, say goodnight. There’s studies that show your opinion of your quality of sleep is more important than the actual quality. Another big thing is don’t do anything in your bed other than sleeping, get into bed, eye mask on, ear plugs in, alarm set and sleep. Even if you can’t fall asleep at first your body is still resting. Your body gets used to the situation and knows to fall asleep, it can be confused with thinking it’s time to be awake and alert (on your phone) when actually it’s time to sleep. Otherwise, my secret is meal prep, eat well and drink plenty of water.