Sleep schedule is probably what you want fixed, there are a multitude of things to aid, in addition to the aforementioned it is also vital to have sleep hygiene if you have problems with sleep.

Sleep hygiene is a lot of things, but the main things:

The bedroom and, most crucially, your bed is for sleeping, if you have a habit of scrolling or watching videos etc in your bed, it will be a lot harder for your brain to be like “well, im in bed now, guess ill sleep”.
Destimulation period before bed, 30-60 minutes before bed get rid of stimulating activity. Some light reading could be okay, better would be meditation, some conversation, a slow walk.
Sleep environment - blackout curtains, low noise or white noise (substitute sounds could be wind, rain, ocean, but not music or generally other sounds)
Actually rigid schedule, especially for bedtime, but also wake-up time.
Got into bed at the time but not sleepy? No screens, no reading. Darkness and your mind - meditate, count sheep, fantasise, think up a novel. Personally i love meditating on the actual process of my mind falling asleep.
Consider short term melatonin to adjust to a sleep schedule or to change a sleep schedule.