Blue Monday: a depressing day of pseudoscience and humiliation

January is a depressing time for many. The weather's awful, you get less daylight than a stunted dandelion and your body is struggling to cope with the withdrawal of the depression-alleviating calorific foods, such as chocolate, of the hedonistic festive period. January is one long post-Christmas hangover.

So there are many reasons why someone may feel particularly "down" during January. But every year, much of the media become fixated on a specific day – the third Monday in January – as the most depressing of the year. It has become known as Blue Monday.

This silly claim comes from a ludicrous equation that calculates "debt", "motivation", "weather", "need to take action" and other arbitrary variables that are impossible to quantify and largely incompatible.

True clinical depression (as opposed to a post-Christmas slump) is a far more complex condition that is affected by many factors, chronic and temporary, internal and external. What is extremely unlikely (i.e. impossible) is that there is a reliable set of external factors that cause depression in an entire population at the same time every year.

But that doesn't stop the equation from popping up every year. Its creator, Dr Cliff Arnall, devised it for a travel firm. He has since admitted that it is meaningless (without actually saying it's wrong).

Dr Arnall is usually described as a Cardiff University psychologist. To be a Cardiff University psychologist you usually have to be employed/publish research from Cardiff School of Psychology, hence I can claim to be one. Dr Arnall briefly taught some psychology-related evening classes at the university's adult education centre. Apparently, this makes him a Cardiff University psychologist. Using that logic, I'm an Asda manager because I once made one of their staff fetch me a discount chicken.

I believe strongly that pseudoscience (like this equation) regularly presented as genuine science in the mainstream media harms the public understanding of science and psychology. It's also disrespectful to those who suffer from genuine depression, suggesting that it is temporary, minor and experienced by everyone, rather than what may be a chronic and incapacitating condition. People with clinical depression often face an uphill struggle being taken seriously, especially as "depression" is such a general term.

But the actual reasons for my grudge against Dr Arnall are far pettier. As a Cardiff-based neuroscience doctor who teaches psychiatry and performs stand-up comedy (not simultaneously) I'm often contacted by well-meaning media types for my "take" on the Blue Monday story.

Back when I was more naive, I agreed to do so, with disastrous consequences.

First came an interview with a local paper. My attempts to explain in detail the fundamental issues of depression (and the laws of reality) that meant the equation was nonsense didn't survive the editing process. The finished article implied that I believed it was all true but "cheer up, here's some jokes from the last three crackers I pulled."

They wanted a photograph, which proved to be an undignified affair. There I was with a photographer in Cardiff Bay, splashing in puddles wearing a black jacket, scarf and cowboy hat. This led to rumours that I was suffering from a breakdown and also that I was the new Doctor Who.

This technically counted as my first published article. That same photo is now also used by the paper if I do anything newsworthy, which, as a result, I try to avoid.

You'd think I would have learned my lesson, but the next year I did the same thing for ITN news, thinking I could put the record straight. My interview was filmed only hours before it was broadcast, so I was confident my point of view would come across, demonstrating my naivety regarding the speed of modern editing techniques. Once again, they adjusted my explanation to fit the predetermined narrative. Humiliation, but with audio this time.

As a result, this comes up every year and I have to go through it all again. Every attempt to "clear my name" fails like the last. A colleague recently asked "isn't it time for Dean's annual humiliation?" I've since vowed to promote proper science wherever possible to counteract the damage I've done by inadvertently lending my limited authority to this pseudoscientific nonsense.

But every year I dread it all coming back up: the very public loss of my scientific credibility. The experience is so degrading and the memories so embarrassing that it's gotten to the point where, for me, the third Monday in January really is the most depressing day of the year.