Yep. I think its a major contributor to my anxiety, overall nervousness, panic, and at worst my depression, bipolar disorder, and schizo-affective disorder (pyschosis).
My hunch is that there is a nervous system disorder, something akin to disautonomic disorders (disorders of the autonomic nervous system) and poor ability for the sympathetic and parasympathetic systems to balance each other out.
I can't sleep without medication, I eventually become psychotic without medication, but I am different than 99% of all patients my doctors have worked with. I am the most sensitive to medicines and have had so many serious drug intolerances that I get the awe of many doctors. They havn't seen anything like me, from top notch psychiatric docs at the best clinics in the US, to former leaders of the National Institutes of Health.
POIS is the missing link.