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by Dara Winters on January 18, 2021

‘Blue Monday’ is used to refer to what is apparently the ‘most depressing day of the year.’ This day usually falls on the third Monday in January, which means today will apparently be the most depressing day of 2021! While on the one hand this might seem like good news, in that at least we’ll soon have the worst of 2021 over with, on the other hand, Blue Monday is a load of rubbish. Not only that, but it’s a lot of pseudoscientific rubbish, and here’s why. 


The term ‘Blue Monday’ was coined by Cliff Arnall in 2004 upon the request of Sky Travel, who wanted to find out when people were most likely to book holidays (and how to encourage them to book more). Arnall came up with a ‘scientific’ formula to calculate the most depressing day of the year. The formula is below:

Where W = weather (though no indication is given as to how this is measured and it also only applies to the Northern hemisphere)

D = debt 

d = monthly salary

T = time since Christmas

Q = time since failing our New Year’s Resolutions

M = low motivational levels

Na = the feeling of a need to take action (again, how this is measured is unclear)


Anyone who remembers anything from maths class might have spotted that several of the variables have different units of measurement, as the formula includes monetary values, temporal values, and feelings as well. The fancy term to describe a formula like this, then, is that it violates the rule of ‘dimensional homogeneity’; in layman’s terms this is simply not a viable mathematical formula.

Another indicator that the way of ‘calculating’ the most depressing day of the year is bogus is the fact that the press release publicising the formula was apparently sent to various academics by a PR company who offered to pay them to put their names to it!

Over the years Blue Monday has been spoken about time and time again but nothing new has ever been said that would indicate that it is anything more than pseudoscience. Here at Tonic, we’re all about real science; why else do you we would be selling such high-dose vitamin drinks? If you’re looking to know when the most depressing year of 2021 will be, we won’t be able to help you any further, but we’re sure we’ll be able to overcome whatever 2021 throws at us; we got through 2020 after all! 

However, if you are feeling depressed or anxious about the current state of affairs, we encourage you to seek help with a medical professional. Please know that you are not alone; and things will get better!


Other sources:



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