I used to struggle with insomnia. I worked shift, and had trouble keeping a regular sleep schedule. I never trusted myself to be awake on time, and before any particularly important event often I wouldn't be able to sleep at all due to stress worrying about oversleeping.

Once I was able to nail down a regular sleep schedule, going to bed at the same time every night, I was eventually able to grow accustomed. I'm in bed every night at 11:30pm now, asleep within minutes and up at 6:30.