I see it as being about working as an emergency services worker (police, fire, EMS) and dealing with PTSD...

"Loud thunder, heavy rain" - the assault on your senses and emotions during and after you deal with people on the worst nights of their lives. The repeated echoing in your head hours or days later from the chaos that you're still trying to make sense of.

"Thin line between joy and pain" - the thin line of men and women who separate joy and pain in their lives, good and evil in society. The thin created to protect and separate personal lives from professional.

"it's a long strange trip it's all insane, you ain't never gonna be the same" - After a couple years, you become a different person.

"Pistons pumping, minds a racing. It's hard to sleep man, when I'm shaking" - trying to sleep after a chaotic night shift full of traumatic events.

etc, etc...

Fantastic lyrics. Every line in the song can be interpreted to support the meaning that the listener finds in it.