I am a newly \[almost\] diagnosed, so I don't have a lot of information at this time about BPD. My psychiatrist wanted me to read a book from the perspective of someone living with a person who has BPD. It deals more in coping strategies for your loved ones, rather than information targeted for those with BPD. 

At work, I will get into a state where my mind feels fuzzy and numb. It generally causes a slight headache, and I feel a type of tunnel vision where I just can't focus on my job duties with a clear mind. I become very distracted and can miss aspects of my job as I try to get through the state of mind. My breathing tends to slow down, and I become very aware of breathing in and out (which causes me to breathe irregularly as well). 

Is this disassociation? If not, is anyone familiar with a term to place on this? I've been logging information for my next meeting with my psychiatrist, and it would be easier if I could put a name on this major symptom I experience.