Pop star Mariah Carey has been silently struggling with bipolar disorder II for nearly two decades.
In an exclusive interview with People, Carey explained that a 2001 hospitalization lead to her diagnosis, where "she didn't want to believe it."
For a long time, she thought she had a severe sleep disorder, since the singer reported not having the typical "counting sheep" insomnia. Instead, she overworked herself, which was later identified as a period of mania.
"Eventually I would just hit a wall," she told editor-in-chief Jess Cagle. "I guess my depressive episodes were characterized by having very low energy. I would feel so lonely and sad—even guilty that I wasn’t doing what I needed to be doing for my career."
Bipolar disorder is previously known as manic depressive disorder. According to the National Institute of Mental Health, bipolar disorder II is characterized as "a pattern of depressive episodes and hypomanic episodes."
During a depressive episode, sufferers may experience overwhelming feelings of sadness, decreased energy levels, insomnia, eating too much or too little, and/or difficulty concentrating during an episode. A hypomanic episode—like the ones Carey describes—is different in that suffers experience elevated moods, have high energy and activity, feel as they can do multiple things at once, become irritable, and/or talk fast.