WHY CAN'T I FALL ASLEEP?

I've always struggled with insomnia. I'm probably not doing myself any favors.
  1. Bob's snoring
  2. It's too hot
  3. It's too cold
  4. The stupid cats are fighting
  5. I can't move or I'll roll over onto the cat
  6. Caffeine consumed anytime within 6 hours of bedtime
  7. The stupid thing I said three weeks ago
  8. Tomorrow's meeting
  9. My hand keeps falling asleep and it feels weird
  10. I miss my grandparents
  11. That one relationship from college
  12. Stupid shit I did way back in college
  13. My future
  14. Global warming
  15. Names for our future dog
  16. What my workout tomorrow will be
  17. Thinking up lists to post here
  18. How to lose some weight
  19. Why wasn't I invited to that wedding?
  20. Upstairs neighbors are walking around. (Our floors are very, very thin)
  21. Was that a gunshot or fireworks?