I get everyone is wired differently but it may be YEARS before you get back to a "normal" natural sleep schedule. Working 3rds on and off for a few years in my early 20s ruined me for life. I almost never get a full 7-8 hours of sleep without some kind of assistance. It's almost impossible for me to fall asleep before 1-2am, then I wake up at 5-6a, sometimes able to fall back asleep but usually not. Then I want (but rarely get) a good 20-30 minute nap about 4pm. Rinse, repeat.