You can find involuntarily inner or intereoceptive processes in many aspects of an organism or human being (sleeping, heartbeat, breathing and so on). That is the same for dp topics in solipsism, perception, emotions, moving and more you can imagine. A trigger (trauma, weed...) makes a suddenly interruption in that normally unconscious fixed unit which starting in vulnerable persons the vicious circle of anxiety and perpetuate it so deploy a alienation to your own self, to people or environment because those functions are disturbed due to give not needed attention
The brain is a high economic system (for all nerve cells actions a lot of oxygen and energy etc is needed) so all repetitive mental processes are going on, will quick automated or gets unconsious. That means that your thoughts still working unconscious and you only recognize conscious your metabolism and your (in that case most negativ or emotional numbed) emotions . After automated thoughts it is difficult to make the link to metabolism and emotions.
An abstract or formalized scheme aforementioned developed in cognitive behavious therapy (cbt) is the S-O - R - K- C-scheme and the A-B-C-D-E- scheme:
O (organism included schedule cognition/thoughts - metabolism - emotions)
R (reaction or behaviour, goes back to organism in metaprocessing)
c (consequences, goes back in metaprocessing)
B (believe; organism with cognition/thoughts - metabolism - emotions)
C (consequences or behaviour, goes back to organism in metaprocessing)
D ( inner debate)
E ( effects like conclusions you do, goes back to organism in metaprocessing)
Sure a better and more effective way than the "brooding chair" is to lower the anxious circle of thoughts, worrying or anxiety in the way you begin a so called "angel circle" of positive thinking, which changes your negative belief sooner or later. With the angel circle you can start the possibility of a normal, well being functioning again, because it will be automated as quick as the viscious circle. This works quicker and better when you get the same conviction as you have/had it in the starting of the viscious cycle, which is proven in accompanying strong anxiety/ panic attacks.