Later, at the conference, Welby said he was taking anti-depressants daily and "on the whole [was] managing very well". He said he had found it "quite easy" to talk about his mental health challenges, but was concerned that many people would worry "because you don't know how your boss will respond".

He added: "Depression is interpreted by many employers as someone who ... is incapable of getting out of bed in the morning and isn't able to do their job properly."

Welby has previously spoken of his struggle with depression. In an interview with GQ magazine two years ago, he said: "I have those moments ... when objectively everything is fine, but you think you are, beyond description, hopeless."

Then he said he had never sought professional help for the "black dog" of depression, using Winston Churchill's phrase, but he acknowledged he might have needed to.

Last year, in a BBC podcast, he talked about mental health alongside his daughter, Katharine Welby-Roberts. She has spoken about her struggles and suicidal thoughts, saying the church did not always know how to respond. "If your first response is, 'Can I pray for your healing?', then you're not listening," she said.

The conference, Faith and Mental Health: a Christian Response, was intended to raise the profile of mental illness and ensure the Church of England responded well to challenges. Prince Harry was due to take part in a private workshop, Kensington Palace said.

Welby said that, along with the rest of society, the church had a history of not knowing how to deal with mental health issues. Many churches offered safe spaces and care, "but it is not universal and we need to work hard on that.''

In an article for the Guardian focusing on rising levels of anxiety and depression among children, the archbishop said stigma was beginning to break down, "but those suffering from mental illness can still feel ostracised, judged and misunderstood".

In Thought for the Day, Welby said during last week's mental illness awareness week, "people from all over the world and all walks of life spoke on social media about their experience of mental illness.

"Much has been made of social media worsening mental health issues. On this occasion it enabled people to share their stories, communicate honestly and feel connected to others.

"We often think it's just us who are struggling, everyone else is OK. That's because we don't talk about our mental health. The stigma is still there, so we feel more alone than we need to."

Christians believed in "a saviour, a rescuer, who knows intimately what it is to suffer. Amidst all the brokenness, Christ weeps with us," he said. "It is my prayer today that anyone who is walking in darkness knows this: you are not alone. You are truly valued and deeply loved. Reaching out and talking to someone can be the first step back into the light."

More than 100 people, including clergy, health professionals, politicians and representatives of charities, attended the conference.

Sarah Wollaston, the Liberal Democrat MP who was a GP for 24 years before standing for parliament, said there was a clear link between poverty and mental health, and that education, housing and income needed to be taken into account in treating mental illness.

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