Mariah Carey has spoken for the first time about her 17-year battle with bipolar disorder.
The singer told People she was first diagnosed with the condition in 2001 after a mental breakdown which resulted in her being admitted to hospital.
Carey, who has sold 200 million records worldwide, said she only recently has sought medical treatment.
She said it came after "the hardest couple of years I've been through".
"Until recently I lived in denial and isolation and in constant fear someone would expose me," she explained.
"It was too heavy a burden to carry and I simply couldn't do that anymore.
"I sought and received treatment, I put positive people around me and I got back to doing what I love - writing songs and making music."
Carey said she is now having therapy and taking medication for bipolar disorder, which has caused her to have periods of depression and hypomania, which can cause irritability and insomnia.
"I'm actually taking medication that seems to be pretty good. It's not making me feel too tired or sluggish or anything like that. Finding the proper balance is what is most important," she told People.
She added that for a long time she thought she had "severe sleep disorder" but whilst working on her album in the studio released "it wasn't normal insomnia".
"I was irritable and in constant fear of letting people down," she added.
"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."
What is bipolar disorder?
- There are different types of bipolar. Those with type 1 experience periods of manic highs and depressive lows. Those with type II experience severe depression and mild manic episodes - known as hypomania - that last for a shorter period of time. Those with cyclothymia experience less severe mood swings, but they can last longer.
- During a manic episode, those with bipolar disorder can feel euphoric and have lots of energy, ambitious plans and ideas. But they can become aggressive, and experience symptoms of psychosis.
- The exact cause of bipolar disorder is unknown. Some experts believe it can be developed as a result of severe emotional distress as a child, as well as genetic and chemical factors.
- One in every 100 UK adults will be diagnosed with the condition at some point in their life.
Sources: NHS, Royal College of Psychiatrists and Mind