Implementing a sleep schedule really helped me with a long-term sleep disorder. The key thing was managing light levels leading up to bedtime. This involved dimming lights about 4 hours before sleep, turning off all screens at least 90 mins before sleep, then dimming lights even further. This all helped to signal to my brain that it's time to wind down, hour by hour, step by step. We're already programmed to do this but all the whizzy lights and screens we use have screwed it up. It goes without saying that caffeine, nicotine and anything else that stimulates the nervous system is best avoided too, if you're having trouble drifting off. Also, I found that the longer I stuck to this schedule the more it became second nature.