It sounds like a 'distraction' coping-mechanism, instead of dealing with what you're really scared of, you start worrying about something you deep-down know is highly-unlikely to happen to you.
Do you have some real-fears that are just a little too much, so you try to ignore them, rather than deal with them?
If so, that could be it, if you learn to deal with your real issues, the anxiety should fade.
Another thing you mention, you're 'weak', and 'wake-up' quickly, which could be a sign you're not active enough, and if you're not active during the day, your body will be saturated with adrenaline when you try to sleep, which creates a bad situation of course.
How to fix it, work-out, do some medium-/high-activity every day, burn-off those hormones so you're physically tired at the end of the day, that's when you sleep best.