Gloomy readers, take heed. There may be a reason why you rolled out bed this morning with a proverbial black cloud looming overhead.

It's Blue Monday, an ill-reputed date that has been dubbed "the most depressing day of the year."

The theory stretches back to 2005 when psychologist Cliff Arnall was asked to figure out the most miserable day of the year.

Using an elaborate math formula, he came up with the third Monday in January – as if Mondays weren't demonized enough already.

Arnall reasoned that Blue Monday is the day when a slew of unpleasant variables such as drab weather, failing New Year's resolutions and Christmas bills collide, creating a veritable maelstrom of negativity.

"Motivational levels also tend to be quite low at this time of year," Arnall told CTV's Canada AM last Blue Monday.

"You've got something called the 'hibernation effect,' when people tend to be more lethargic, they eat more than they really need."

There are some questions, however, about whether Arnall's theory is actually valid.

Arnall was asked to whip up his formula for a public relations firm as part of a marketing campaign for travel company, Sky Travel. What better reason to go on vacation than to lessen the effects of the "most depressing day of the year?"

Psychiatry lecturer Dean Burnett is one of many critics who have dismissed Arnall's equation as ludicrous. In particular, he takes issue with the theory's liberal use of the word "depressing."

"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," he wrote in an editorial for the Guardian.

Even Arnall, the harbinger of doom himself, has conceded that his theory is not particularly helpful.

While he still stands behind his Blue Monday formula, Arnall told London's Telegraph newspaper two years ago that the date has become a "self-fulfilling prophecy."

Instead of dwelling on the date, he urged people to focus on happiness year round.

"I'm pleased about the impact it if it means people are talking about depression…but I'm also encouraging people to refute the whole notion of there being a most depressing day and to use the day as a springboard for the things that really matter in your life," he told the paper.

Still, many continue to latch onto the idea of Blue Monday.

This year, it didn't take long for the topic "Blue Monday" to trend on Twitter, landing only a few spots below #HappyMLKday -- a tag honouring Martin Luther King Jr., the famed civil rights activist who makes headlines on the third Monday of January for entirely different reasons.