Apparently, the third Monday in January (which this year, falls on the 21st) is 'Blue Monday' - the most depressing day of the year, when a post-Christmas hangover/debt mountain, plus some other credible-sounding stuff, combine to make us all feel awful. Granted, January is a pretty gloomy month (I was shocked to see a blue sky today, having forgotten what one looked like), but why is that particular day more depressing than any other?

Well, of course, it's not. Blue Monday was actually invented by a psychologist to help promote some travel company - if you don't believe me, read this psychology blog in the Guardian. In one way, as someone who spends their time trying to help people with problems like depression, I am pleased that the mainstream media now openly discusses mental health. People with depression may be isolated and ashamed of being depressed. They might also feel like no-one understands them, or that there is something uniquely wrong with them - the more they read about other people just like them, the less of a stigma depression will seem.

In another, I despair at stories like this. For starters, it's important to distinguish between feeling a bit glum (as we all might do on a grey winter's day) from genuine depression, which can be a serious, extremely debilitating condition. If you have moderate or severe (as opposed to mild) depression, you are likely to need treatment, with cognitive behaviour therapy (CBT) clinically proven to be the most effective form of 'talking therapy.' Regular exercise is also a great way to tackle persistent low mood (and has been proven to be as effective as antidepressants, especially for mild to moderate depression). Whether you take medication is up to you, but there is good evidence to suggest that antidepressants can help, particularly for more severe forms of depression.

And, if you want to understand the cause of real depression, it's not a hefty credit card bill, but a triggering of negative beliefs about yourself, your experiences and the future (what Aaron Beck, the founder of cognitive therapy, called the "cognitive triad" of depression), often because of a major loss, such as bereavement, divorce or redundancy. Depression is a natural human response to overwhelming stress or upset, when these dormant negative beliefs get triggered and, unless you receive treatment, you may end up spiraling downwards.

So when I say depression is all in the mind, I certainly don't mean it's not real (because depression is very real, and can be extremely unpleasant), just that the cause of this disorder can be found in unhelpful patterns of thinking, stemming from those negative beliefs. Fortunately, this means the solution to people's depression is also in their minds, if they get a little guidance in how to change the way they think, as well as doing things that help them feel better about themselves.

In short, the most depressing thing about Blue Monday is that it's a load of cobblers, which does a disservice to the millions of Britons suffering from a genuine mental health disorder.

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