Bipolar disorder is characterized by extreme changes in mood. Mania occurs at the zenith of these changes — it's a " good" mood taken to its most toxic form . For Carey, this meant working overtime and driving her body into an adrenaline-fueled insomnia. (Insomnia is a common symptom of manic episodes.) Carey added that her depressive episodes would leave her sluggish and feeling guilty. "I would feel so lonely and sad — even guilty that I wasn’t doing what I needed to be doing for my career," she said.