Keeley Hawes has revealed that she has suffered from depression since she was a teen.
The Line of Duty star, whose character Lindsay Denton in the police drama is also plagued with the same condition, added that she still hasn't found a cure for it.
"I started suffering with depression when I was 17," Keeley told Red magazine. "[Therapy] hasn't worked for me. I've got a chemical imbalance that has to be managed. And then it's fine."
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Keeley Hawes has suffered from depression since she was 17
"It's not something that's cured and then goes away and you move on," she added. "You are always aware, even if it's only on a bad morning here and there, that it can escalate quickly."
Keeley, who has starred in Spooks and Ashes to Ashes, will play a cameo role in the eighth series of Doctor Who. The 38-year-old actress will guest star as Ms. Delphox – a mysterious banker who is described as "a powerful, out-of-this-world character with a dark secret".
Last spring Keeley joined Peter Capaldi and Jenna Coleman on the sci-fi set to film her scenes.
"I am delighted to join Doctor Who and to be working with this incredible team," said Keeley of her appearance. "Ms Delphox is a great character and someone I've had a lot of fun playing."
Matthew Macfayden and Keeley Hawes have two children together
The former model is married to Matthew Macfadyen, with whom she has two children – nine-year-old Maggie and seven-year-old Ralph. She also has another teenage son Myles from her previous marriage to cartoonist Spencer McCallum.
Like many of the UK's biggest TV stars London-born Keeley honed her craft at the Sylvia Young Theatre School. After graduation and a brief period during which she modelled and worked as an assistant with a glossy magazine, she made her debut in TV drama Karaoke in 1996.
A number of TV and film roles followed – the most high profile being hit drama Spooks, which she joined in 2002, and 2008 time travel drama Ashes To Ashes.
The elocution lessons she took during her time at theatre school paid off, too. She was chosen to lend her voice to feisty action heroine Lara Croft in the Tomb Raider video game franchise.