RUTH Davidson has opened up about a teenage mental breakdown that led to her self-harming and considering suicide.

In a candid interview with The Sunday Times to promote her new book, Yes She Can, the Scottish Tory chief also tried to draw a line under rumours of a bid to replace Theresa May, saying she values her relationship and her mental health too much.

Davidson’s decision to disclose her battle with the “black blanket” of depression, was welcomed by mental health charities.

In her book, the Edinburgh MSP says when she was 17 she was sent into a “total tailspin” after a boy in her home village committed suicide.

“I started hurting myself: punching walls, cutting my stomach and arms with blades or broken glass, drinking far, far too much and becoming belligerent and angry, pushing people away. I was punishing myself and hating myself for it at the same time.”

Davidson was later diagnosed with clinical depression and put on antidepressants, an experience that, for her, did not improve her condition.

“After starting medication, I had desperate, dark, terrible dreams that were so vivid, I couldn’t tell what was real,” she said. “I became anxious and paranoid. I started having suicidal thoughts.

“Every time I went back to the university health centre with a fresh set of injuries, the doctor on duty just doubled my dose and things got worse.

“In the end, I was on the maximum dosage allowed and became so scared of sleep that, in my second year, I spent a whole term living nocturnally. I stayed up through the night and only went to bed once my flatmates had left for lectures.“

For Davidson, the improvement in her health came from an active decision to “will” herself better. “I had mocked the leaflets I was given on the diagnosis – NHS instructions to do light activity, like housework or clearing out my cupboards. But eventually I made a decision to will myself better. I resolved to build a structure to my days and weeks, to set short- and medium-term goals, to engage in purposeful activity that had a measurable outcome, to take regular exercise, moderate my drinking, go back to church and be kinder to myself.”

The Tory leader says she knows that “drug therapy helps millions” and that with a different GP or at a different time she could have received treatment that would have helped her more. She admits that she’s “still frightened of going back to the psychological place I once inhabited.”

“When I have periods of heightened anxiety, or I can feel the weight of the black blanket start to descend, I go back to what I know works for me: structure, exercise, forward momentum, measurable outcomes.”

Asked if she would ever run to be Prime Minister, Davidson, who is seven months pregnant, told The Sunday Times: “No. I value my relationship and my mental health too much for it. I will not be a candidate.”

She added: “On a human level, the idea that I would have a child in Edinburgh and then immediately go down to London four days a week and leave it up here is offensive, actually offensive to me.”

Toni Giugliano from the Mental Health Foundation praised Davidson’s courage for speaking out.

“Stigma is still very present in our society – the Mental Health Foundation’s research found that 40% of Scottish employers wouldn’t hire someone with a mental health problem. That’s why it’s so important for CEOs, bosses and national leaders to speak out about their own experiences and help drive change.

“The truth is that mental ill health is still seen as a weakness, especially in public life. Ruth’s decision to speak out takes courage and will hopefully encourage others to do the same.”

SAMH tweeted: “Thank you @RuthDavidsonMSP for speaking so openly about your mental health.”