In Eileen Chang's novel Half a Lifelong Romance, a passage describes the joy of seeing Saturdays marked in green on a calendar, surpassing even the red Sundays, because “although Sunday was marked in red, it carried a tinge of sunset melancholy.”

Despite being written in a different era, the sentiment about the inevitable transition to work or school after Sunday still resonates today.

This feeling of lethargy and gloom at the start of the week is often referred to as "Blue Monday." In English, the term "blue" is commonly associated with sadness, which explains the connection to the melancholy of returning to work. However, could there be other origins for this expression?

The phrase "Blue Monday" was already in use during the medieval period in Europe. One explanation suggests that workers, particularly craftsmen, would often drink heavily and brawl on Sundays. By Monday, they would return to work covered in bruises, hence the term "Blue Monday."

Another interpretation comes from Northern Germany, where "blue" was slang for drunkenness. After indulging in alcohol on Sundays, workers would return on Mondays hungover, a state referred to as "blue."

Scholars have also noted that in standard medieval German, the word "blue" carried connotations of emptiness or hollowness. This meaning was further associated with the infinite, unattainable quality of a blue sky, symbolizing a sense of void or detachment. Workers, especially craftsmen, were said to exhibit a similar vacant, listless state on Mondays as they struggled to resume their duties.

A different theory ties the phrase to cultural practices during Lent. On Mondays in this period, the gathering places would drape their altars with blue cloth, which gave rise to the name "Blue Monday."

Regardless of the origin, most explanations—except for the special association—relate to a sense of weariness or reluctance to work. During the medieval period, craftsmen typically worked 15 to 16 hours a day. Scholars believe that without the frequent cultural holidays offering reprieve, the single day off on Sunday would have been insufficient to sustain their willingness to labor. In comparison, modern workers generally have better working conditions. Instead of succumbing to the Monday blues, perhaps it is better to rally and embrace the workweek with renewed energy before winter fully sets in.