Feeling bummed? It should be easier than ever for you to find pop songs that match your dark mood.

A scientific analysis of pop music over the past 65 years found song lyrics have become "sadder" and "angrier." Especially angrier. 

A professor and grad student from Michigan's Lawrence Technological University analyzed the lyrics of more than 6,000 songs that made it onto the Billboard Hot 100 between 1951 and 2016. Billboard charts are often used to identify trends and preferences of both artists and fans.

Computer science Professor Lior Shamir and computer scientist Kathleen Napier turned to a program that analyzed the sentiment of songs' lyrics, looking for words or phrases it can associate with feelings. So, for example, sadness dominates the line "Turn around, even now and then I get a little bit lonely and you're never coming 'round," from Total Eclipse of the Heart by Bonnie Tyler. 

The team's analysis includes terms like "Pearson correlation coefficients" that aren't exactly music to my ears. But the bottom line, according to the research, is that anger, disgust, fear, sadness, tentativeness and conscientiousness have increased over time, while joy, analytics, confidence and openness have declined. The study was published in the Journal of Popular Music Studies.

The study also found pop lyrics expressed more fear during the mid '80s, and the fear decreased sharply in 1988 (which, for you history buffs who might be looking to speculate about the connection between lyrics and the cultural zeitgeist, is just before the Berlin Wall fell, ending the Cold War). Fearful lyrics surged again in 1998 and 1999, with a sharp decrease in 2000 (Y2K anyone?).

Songs with the highest anger scores include Pink Floyd's Another Brick in the Wall from 1980, Tina Turner's 1985 song Better Be Good To Me and Ne-Yo's When You're Mad from 2006.  

Don't blame the musicians for all the pouty faces though.

"The change in lyrics' sentiments does not necessarily reflect what the musicians and songwriters wanted to express, but is more related to what music consumers wanted to listen to in each year," Shamir says.

And that, of course, like fashion, varies with the times. People listened to music in the 1950s largely for fun and entertainment, so lyrics tended to express more joy and less anger, Shamir points out. During the mid to late 1960s and early 1970s music became a tool for social activism, so it makes sense those lyrics would reflect anger and disgust.

For their research, Shamir and Napier used Tone Analyzer, a computational linguistic tool developed for IBM's Watson question-answering computer system. Watson, by the way, kicked off fears of robots taking all our jobs when it beat human opponents on the TV quiz show Jeopardy in 2011. Has anyone written a song about that yet?

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