I don't know about this. Is it a possibility? Sure. But I don't think that it applies to everyone who has trouble sleeping. I know that my Dad had trouble sleeping when he was in his 40's, but he knew exactly why... too much stress at work. But sometimes life doesn't have immediate options for reducing that... and so you have trouble sleeping and do the best you can.
As for myself, I rarely have trouble falling asleep, but wake up probably at least 5-10 times each night, and often can't fall back asleep easily. So I'll wind up getting 4 hours of broken, choppy sleep several times a week (and 6 hours of broken sleep, tops). Sometimes I just give up and get out of bed. I've been to the doctor several times (and given a couple of short-term prescriptions, neither of which did a thing), structured my sleep schedule, made sure I get enough exercise early in the day, etc. and haven't yet found a solution. But it's no fun. Wish I had better advice, but the best I've come up with is "relax and try not to think about it" - which is tough to do when you're lying in bed, tired and yet wide awake.