What would you say if I were to ask you what is expected to be the world's second biggest health problem after heart disease by 2020? Cancer? Aids? Obesity?

You may be surprised to learn that it is likely to be depression. Though perhaps you are not that surprised?

It is generally accepted that 1 in 5 people or 20 per cent of the population will suffer from a depressive illness at some point in their lives. A recent study of 2,000 women and girls found that almost a third of women over 18 had taken anti-depressants. A second study revealed that 30 men under the age of 45 commit suicide every week. A story in a Teacher Support Network e-newsletter on the suicide of a teacher was one of the most read stories, we have ever had. Clearly, depression and mental health issues not only interest us, but directly affect either us or someone we know.

Yet, be honest, how many of you know if your colleague has ever had depression? Have your school leaders ever taken anti-depressants? Statistically, it is likely, that someone in the staffroom has a mental health issue, but do you actually know?

I am not saying that teachers or anyone else should reveal anything about their medical history that they do not want to, but why is it that we are so afraid to talk about the problem?

Those that are diagnosed with the world's biggest health problem heart disease show few qualms in sharing their stories or their experiences. There are reality TV shows and media reports dedicated to avoiding the risks of heart disease, while advertising agencies have long seen the financial benefits of highlighting the anti heart-disease properties of their products. Likewise for other health issues, where warnings on cigarette packets are a legal requirement and national sexual health campaigns are commonplace.

I am not saying these are wrong. I am just asking where are the same for depression? Where are the labels on bottles of alcohol saying 'this may cause depression'? Where are the gym advertisements linking the benefits of exercise to the reduction of mental health problems?

Similarly, when a colleague is diagnosed with an illness such as heart disease or cancer, it is likely they will share their illness with their co-workers, not just for their understanding, but ultimately for their support. There is rarely a concern for how the illness will impact on future careers or fears of sharing weakness.

Yet, when a colleague is diagnosed with depression or a mental health problem, it is more likely that they will not share their illness exactly because of concerns over the impact on their career or the effect on professional relationships of sharing these weaknesses. I have even heard of some workplaces, and luckily these are few and far between, where depression is simply seen as an excuse for time off. Is it any wonder that people do not want to talk?

Perhaps, I am going too far, but when I read of the suicide of another stressed out teacher or shocking figures on the state of the nation's mental health, I wonder what would happen if we spoke about the issue more? What would happen if we admitted, not necessarily that we ourselves had suffered from depression or a mental health issue, but simply that we know someone who did? Would we continue to suffer in silence or would we begin to see just how many people are affected by what is expected to be the world's second biggest health issue?

Today, we would like you to speak up if you know someone who has been affected by depression or mental health:

• Update your facebook status or your twitter account to 'speaking up about depression.'
• Change your photo to a mouth and then ask your friends, family and facebook groups to do the same.
• Ask them to ask their friends and family to do similar and so on, so that we begin to see the scale of the problem and how it affects us all.

Let's all speak up, then, who knows what will happen?