how to fix your sleeping cycle :
fast way !
if your reading this at 3 am dont sleep just continue your day drink coffee real early if you need it but not late than youll really be tired like extra tired so youll fall asleep in the time that you want like say you wanna be asleep by 9 pm , get ready to sleep by 8 am then it will probably be 8:30 depends on how much you take in the bathroom , if your in the bed and cant sleep (which will be impossible) you can read a book but never scroll through your phone because it will wake you up more
this trick worked for me really well but idk about you
tips if you dont want this way ^:
1) dont scroll through your phone atleast 30 min before you sleep , because theres something about your phone that makes you wanna stay awake maybe from telling yourself this is the last youtube video ill watch
2) try drinking hot milk or hot chocolate milk to help you fall asleep
3)read a book , it will help tire you so you can sleep and its a good exercise for your brain

hope this was helpful !