Was in dull meeting w/ a bunch of stuffed shirts and I was so beat - I could imagine myself crawling under the table and using some guy's wingtips for a pillow.
Then later at home I stared at the ceiling for hours...wide awake.
"Too tired to sleep" is what I call it.
Knock-out drugs put me to sleep initially, but I awaken in about 2-3 hours and I'm fidgety....that's worse than insomnia.
Could try a natural supplement like melatonin.
Here's what the Mayo Clinic says about side effects:http://www.mayoclinic.com/health/melatonin-side-effects/AN01717
But simple white noise works better for me than anything else I've tried.
And sometimes I just have to take a day off work, sleep-in, and hope it breaks the cycle.