Adut Akech has revealed the private pain behind her famous smile as she strives to help others living with a mental health condition.

To onlookers, the South Sudanese-South Australian supermodel, who turned 19 on Christmas Day, has the world at her feet.

In the past 12 months, Adut has become, in Vogue Australia editor-in-chief Edwina McCann’s words, “the biggest fashion superstar in the world”.

Adut, who came to Australia as a child refugee from Africa, won Best Australian Model at the Australian Fashion Laureate awards.

Starring in shows and campaigns for global brands such as Chanel, Saint Laurent and Valentino, she has also been recognised by influential industry website models.com as the world’s top female model.

But on Tuesday on Instagram when Adut posted a photo of herself smiling, wishing her more than 270,000 followers a happy new year, she opened up about her ongoing mental health struggles.

“I’ve suffered from really bad depression and anxiety for a while now and I still do but I’m learning to handle it better now but it’s a daily struggle and not every day is a ‘good’ day,” Adut wrote.

“I would wake up every morning crying but put the biggest smile on my face and tried my hardest to push through the day pretending I was fine then I’d come home and cry some more and go to sleep. This became my routine for the majority of 2018 and in all honesty it was so draining mentally, physically, emotionally and spiritually. I don’t know how I’m still here today but I’m so grateful I am.”

Saying depression was “no joke”, Adut reached out to “everyone who suffers from it”.

“I just want you to know that you’re not alone in this battle, I’m with you and so are many people in the world,” she said before thanking family and friends for standing by her.

“I can honestly say that you guys have saved my life because I lost all hope and faith in life, the love and support you gave me every single day allowed me to see my purpose for being on this Earth.

“So I can’t stress enough to the people who know someone who is suffering from any mental illness, I pray that you guys just be there for them and be their brightest light through their darkest days.”

Adut also urged those suffering to seek help.

“For 2019, I pray for those who are sick to get well soon, those in need of help to get the help that they need,” she wrote.

“I pray that God gives you nothing but happiness and blessings this year and for the rest of your life. ”

The Advertiser reached out to Adut for comment on Tuesday through her manager, but she is on holiday in Melbourne with her family.