Mandie here, who happens to be (although not that deep into unhygenics) one who also slips into this when very emotionally upset.
I dont think i have ever said this on here,because its embarassing for me. But I will sometimes go days without showering, I cant remember when i last brushed my teeth(oh wait - i do brush them when I throw up, which due to my meds is semi daily - but i dont on any real schedule) and I will wear clothes for days on end, if i dont leave the house.
For me, it comes from two things. One being depression and not caring about myself, and the other is I have semi severe memory issues and I just plain do not remember.
I know the former is true because when I feel special, or good about myself, i clean all up and put makeup on. otherwise, I dont care.
The memory thing is huge. Huge. I need a calendar in every room or else I cant remember the date. I miss everything for the same reasons.
So theres likely ALOT at play here. I am not sure what can be done.