BPD Awareness Month 11
Day 11 of Borderline Personality Disorder Awareness Month.
Another feature of BPD is pronounced mood swings. In the words of Wikipedia, "affective instability due to a marked reactivity of mood (e.g., intense episodic dysphoria, irritability or anxiety usually lasting a few hours and only rarely more than a few days)." The word "reactivity" is key--from what I know, one of the things that distinguishes BPD from other mood disorders is that the person's mood shifts are usually triggered by external forces, such as an argument with a friend or a bad day at work.
To learn more about BPD, see this page on my tumblr.