Blue Monday is a name given to a day in January (typically the third Monday of the month) purported to be the most depressing day of the year. The concept was first publicised as part of a 2005 press release from holiday company Sky Travel which claimed to have calculated the date using an equation.
The idea is considered pseudoscience,[1] with its formula derided by scientists as nonsensical.
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All details taken directly from provider content at http://en.wikipedia.org/wiki/Blue_Monday_(date)