If someone is sad or anxious they might be in a depressed mood
Yes its a new age problem thats growing bigger every day, are you anxious sometimes?
No not really. I've known people with Borderline personality disorder though. 
What is that? i havent heard of it
Borderline personality disorder
Borderline personality disorder (BPD), also known as emotionally unstable personality disorder (EUPD), is a long-term pattern of abnormal behavior characterised by unstable relationships with other people, unstable sense of self and unstable emotions. There is often dangerous behavior and self-harm. People may also struggle with a feeling of emptiness and a fear of abandonment. Symptoms may be brought on by seemingly normal events. The behavior typically begins by early adulthood and occurs across a variety of situations. Substance abuse,
the depressed mood caused by bipolar disorder, but a positive event would potentially lift the depressed mood of someone with BPD. Similarly, an undesirable event would not dampen the euphoria caused by bipolar disorder, but an undesirable event would dampen the euphoria of someone with borderline personality disorder.
Third, when people with BPD experience euphoria, it is usually without the racing thoughts and decreased need for sleep that are typical of hypomania, though a later 2013 study of data collected in 2004 found that borderline personality disorder diagnosis and symptoms were