Mariah Carey has said she is no longer living in "denial and isolation" after being treated for bipolar disorder.
The singer has told celebrity magazine People that she "didn't want to believe it" when she was diagnosed in 2001 after receiving hospital treatment for a physical and mental breakdown.
She said: "Until recently I lived in denial and isolation and in constant fear someone would expose me. It was too heavy a burden to carry and I simply couldn't do that anymore."
The 48-year-old is now in therapy and taking medication for bipolar II, which involves periods of depression and hypomania, and often involves irritability.
Carey said the medication is having a positive effect and is not making her feel too tired or sluggish.
"I got back to doing what I love - writing songs and making music," the mother-of-two said.
She said that she first thought she was suffering with "normal insomnia" as she could not sleep and was "working and working and working".
The star said she was "irritable and in constant fear of letting people down" and that she later learned she was "experiencing a form of mania".
"Eventually I would just hit a wall. I guess my depressive episodes were characterised 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."
According to the NHS, bipolar disorder is characterised by extreme mood swings, and includes periods of extreme highs and lows.