Blue Monday – known as the most depressing day of the year – falls on January 15 this year. But what makes this day so sad?

Coined in 2005 by UK travel company Sky Travel, the term Blue Monday usually refers to the third Monday in January.

At the time, the company announced that it had concluded that, based on an equation that used factors such as weather, debt, monthly salary and amount of time since vacation, levels of "happiness" were lowest on the third Monday of the year.

So is Blue Monday really the most depressing day of the year?

Short: No. It was a marketing ploy to sell travel packages. But why is it still talked about? Maybe because it relates to something that many people feel. It can be a symptom of an actual medical condition known as  seasonal affective disorder  (SAD).

During this time, you may have feelings of sadness and feel melancholic, by definition, you may "experience feelings of depression or deep unhappiness associated with experiencing the cold."