American psychologist and professor of psychiatry, Kay Redfield Jamison, is one of the world's foremost authorities on bipolar disorder. She's spent her career researching, lecturing, and writing seminal books on the condition—a condition that she also happens to have had her entire adult life. In her memoir, "An Unquiet Mind," Jamison details what it really means to be bipolar. She writes of not sleeping for days on end, of feeling long periods of euphoria, and filling whole notebooks with her racing thoughts and grandiose ideas. While in these manic states, she experienced a tremendously inflated sense of self-esteem and did impulsive things that felt good at the time but had painful consequences, like going on lavish shopping sprees, engaging in promiscuous behavior, racking up credit card debt, and emptying her bank accounts. But these episodes were followed by emotional crashes, crippling bouts of depression that sent her into a suicidal spiral. At the age of 28, Jamison tried to kill herself by taking an overdose of lithium, lapsed into a coma, but thankfully emerged from it determined to find help through medication and therapy. Through her research and writing, Dr. Jamison has pioneered our understanding of bipolar disorder, depression, and the nexus of mental struggles that we now think of as mood disorders. And she's probably one of the best ambassadors we have for all those people who live successful, productive lives with mental illness. Just like the anxiety disorders we talked about last time, mood disorders are misunderstood. They're diluted by depictions of depression as something that can be treated with one day at a spa, or descriptions of people as manic-depressive just because they were sad yesterday and aren't today. As students of psychology, our job is to understand what mood disorders really are, how they manifest themselves, and what might cause them. And as you've probably guessed, this can be pretty tough terrain to explore. These disorders can take people from terrifying highs to pits of despair that seem all but bottomless. But, in between, there's what Jamison has called a rich, imaginative life, all made possible by your moods. **INTRO** We've been talking a lot about terms and concepts that mean something different than what you think they mean, but this time, the term "mood" is not one of those. In a psychological context, moods are pretty much exactly what you think they are—emotional states that are even more subjective and harder to define than the emotions themselves. And while psychologists have defined about ten basic emotions, moods tend to fall into two broadly and infinitely variable categories. You've got the good moods and the bad moods. Probably the most important distinction between emotion and mood is that moods are long-term emotional states, rather than discrete, fleeting feelings. And mood disorders, which are characterized by emotional extremes and challenges in regulating mood, tend to be longer-term disturbances. These include depressive disorders, typified by prolonged hopelessness and lethargy, and bipolar disorders, the most prominent of which involve alternating between depression and mania. Depression's been called the common cold of psychological disorders, which is not to say that it isn't serious, but it's common, and it's pervasive, and it's the top reason people seek out mental health help. We've all felt down before, obviously, often in response to a specific loss—a breakup, or a lost job, or the death of a loved one. And the fact is, you probably should feel bad at times like those. It can actually be good for a mind and body to slow down to help digest losses that you experience, but in general, sadness is temporary. It's when sadness and grief extend beyond the generally accepted social norms, or plunge into a depth that causes serious dysfunction, that you find yourself in the territory of depressive disorders. The DSM-5, our handy-if-super-flawed user's guide to psychological disorders, officially diagnoses a major depressive disorder when a patient has experienced...