It seems you want to focus strictly on mood and because mood swings can be drastic it might be better classified as a mood disorder. That, to me, is like looking at a piece of the picture rather than looking at the picture as a whole. I can only speak for myself but when I feel intense rage or intense sadness it's a result of an interaction with another person, and the changes in mood are usually linked. If someone doesn't phrase things correctly or if what they say doesn't match their facial/body language or if there's a perceived sense they're lying to me that can set me off into a rage, and it can be over something trivial. After the rage, I become apologetic and when that doesn't work, I become intensely angry again and when I don't get the desired results from that, I can become needy/clingy practically begging for forgiveness and then intensely sad/depressed. I'll give a recent example.. I exchanged some emails recently with someone and they said I could txt them if I want and if not they understood. That set me off. If they had just said "text me" I would've been fine, but the way it was phrased especially the part about if I didn't they understood, made me think they really didn't care one way or the other. I replied basically telling them to **** off and never contact me again. I've had interactions with people in the past where I've impulsively changed my phone number, and then contact them sometimes within a few hours to give them my new phone number. I don't rage or become intensely sad out of the blue or randomly it's as a result of some sort of interaction with another person.

We're like other personality disorders in the sense that we're manipulative too. "If you don't talk to me I'm going to kill myself", I do a nice gesture for you or get you something, it's not to necessarily be nice but it's really so you do the same for me. If you don't that can lead to intense anger/sad. Many of us don't know or have the skills to interact with others.

Many of us also lack a stable identity. I've read here and elsewhere situations where others with bpd have taken on the characteristics of someone they see on tv, and when that gets old or someone new comes around that they like better they take on those characteristics.

So it's not just mood, but it's the inability to have effective/rational interactions with others that affect the mood, and it's the pervasive pattern of interactions with others and the manipulative tactics that makes us a personality disorder rather than a mood disorder.

For me I try to keep people at a distance by not allowing them to get close to me. To do my best to remain detached so I don't have to deal with the intense anger/sadness. I'm not better. I've just taken on a new dysfunctional way of coping by cutting off my emotions and remain detached. It's when I make the occasional mistake of allowing someone to get to close to me at some point the pattern will repeat and there goes the friendship followed by intense sadness that will last weeks and sometimes months.

Those are my thoughts on the subject.