Been there myself plenty of times.

On my mind 24/7.

I feel you, this is a mood and not a good one

Fun times!....not -_-

Well I find that distracting brain with other stuff helps there.

Ive been there before... many times. I find that helps is making a hot cup of herbal tea (I recommend sleepytime by celestial seasonings) and reading a book, comic, manga, whatever (I would avoid using your phone, tablet, etc as the bright screen and what you see on social media can actually make things worse) to help calm me down and drift off back to sleep.

I've chosen the unhealthy alternative to that. Push for just one more minute of television. Fall asleep from exhaustion. Wake up to yet more TV.
It will bring strange dreams. But then, I don't get to lay around in the quiet AM hours, pondering why I once listened to WW1 era music that I knew just a little too well and have an accompanying image memory of standing around in a barn while the fresh hay is spread out across the ground, why the metal signs are on the wall and right out the open double doors looks like a field of crops under a sunny day. (Never lived one second on a farm with a big barn that grew crops. This vision was vastly stronger than some odd daydream. So, I choose former life memory brought forth from music... I never heard a day in my life... aside from that one day.)

This is an unpleasantly-familiar feeling :(

I experience these thoughts all the time at work.

Sometimes I experience full on panic attacks from this...

So many people who can relate.