Insomnia is a gross feeder.
It will nourish itself on any kind of thinking, including thinking
about not thinking. - Clifton "Kip" Fadiman.
I
can certainly relate . As I write this, I am in a state of a
continuous fatigue, caused by my own anxiety, and expeditiously, by
severe insomnia.
Insomnia is a strange creature because it has no
discernible pattern. One might suffer from it for days, even weeks,
sometimes with no feasible cause. Then it just suddenly disappears, and
it has no timetable when, and if, it will return.
For me, it has
substantially to do with the fact that my mind is forever moving. Each
individual thought process is it's own highway. Some are racing like a
drive on the Autobahn, fast and free. Then there are the ones that end
up like a traffic jam of the Santa Monica Freeway during rush hour.
There are more of the latter then of the former.