Beverley Callard: I couldn't talk about my depression
Research suggests that more than half of people with a mental health problem wait over a year before talking about it.
The campaign group behind the study, Time to Change, says social stigma is still stopping people from opening up.
Among those supporting the campaign is Beverley Callard, who plays Liz McDonald in Coronation Street.
She told the BBC about her experience of depression, and has been to meet others who have also had to cope with it.