UNITED NEWS INTERNATIONAL (UNI) — Singer Mariah Carey has opened up about her struggle with bipolar disorder.

Bipolar disorder occurs when someone’s mood quickly changes from happiness to depression with episodes lasting for prolonged periods of time.

Carey told People magazine in an exclusive article that she was first diagnosed in 2001.

She later tweeted on Wednesday, April 11, “I’m grateful to be sharing this part of my journey with you.”

Thinking she had a sleep problem, Carey said, “I would feel so lonely and sad, even guilty that I wasn’t doing what I needed to be doing for my career.”

Carey is one of many celebrities to have opened up about struggling with mental health.

Singer Selena Gomez opened about about dealing with depression and anxiety while Chrissy Teigen has written about facing postpartum depression after the birth of her daughter Luna.

Carey’s full story will be available on Friday.