Delegate Carolyn Spence from BT moved Prospect's successful motion to the Women's TUC, which noted that women are more likely than men to work part-time, in jobs of lower status and tend to have greater domestic and caring responsibilities.

Women are more likely to report health problems than working men, but competing demands on their time in an unsupportive workplace culture could also explain their higher levels of treatment for mental ill health, the motion said.

The TUC was urged to help reps work together to provide:

• effective stress risk assessment and management, including training for line managers
• resources to show the links between good work and good mental health and encourage workplace dialogue aimed at de-stigmatising mental health
• policies and arrangements enabling flexibility in work/life balance and tackling workplace bullying and harassment.

Earlier in the week, Prospect's packed seminar heard from Alan Bradshaw, a business psychologist, whose consultancy Work-Life Solutions jointly hosted the event.

He said research shows a strong business case for employers acting to prevent and reduce stress at work, particularly when taken against a backdrop of legal or reputational risk.

Bradshaw said stress was now the main cause of sickness absence. One in six workers experiences stress, anxiety or depression and one in five fears that admitting to it would increase their risk of redundancy.

He listed 10 useful checklists or standards, including the Heath and Safety Executive's management standards and guidance from the National Institute of Clinical Excellence.

Emma Mamo, policy and campaigns manager at the charity MIND, said the culture of silence around mental health was a major problem. Employees felt unable to speak up for fear of discrimination, exacerbating their distress and potentially leading to legal consequences.

"But if support is not put in place, problems can spiral into a health crisis, with increased costs for individuals and employers. It is employers who need to take the first step in confronting the elephant in the room."

Disclosing a mental health problem could make it easier to manage, and simple adjustments or changes in attitude could make all the difference – for example, flexible hours and alternative working patterns; phased return-to-work policies and increased supervision or support.

Mind's website offers advice and resources.

Prospect health and safety officer Sarah Page said people were facing difficult times and this made it hard for union reps supporting them, particularly where senior managers and leaders would not concede a stress or mental health problem in the workplace. "Reps securing evidence is then vital," she said.

Delegates were invited to experience body-mapping – a participant-driven tool for raising awareness of stress symptoms.

• This tool and other resources are available via Prospect's stress web pages. Also see the WorkTime YourTime campaign
• Prospect's Disability Equality Negotiators' Guide has also been updated.