A study of 500,000 songs released in the UK between 1985 and 2015 revealed that pop music has sonically decreased in happiness and increased in sadness.
In a report published in the journal Royal Society Open Science, researchers at the University of California at Irvine examined hundreds of thousands of songs and categorised them by their mood.
"'Happiness' is going down, 'brightness' is going down, 'sadness' is going up, and at the same time, the songs are becoming more 'danceable' and more 'party-like,'" co-author Natalia L. Komarova told The Associated Press.
However researches made clear that the decrease in the "happiness" index doesn't mean all popular tracks in 1985 were happy and all popular tracks in 2015 were sad.
Researchers were studying the average trends surrounding music's "acoustic properties" and the "moods describing the sounds."
The study found songs in 2014 like "Stay With Me" by Sam Smith, "Whispers" by Passenger" and "Unmissable" by Gorgon City to have a "low happiness" index.
Tracks from 1985 like "Glory Days" by Bruce Springsteen, "Would I Lie Yo You?" by Eurythmics and "Freedom" by Wham! had a high "happiness" index.
"The public seems to prefer happier songs, even though more and more unhappy songs are being released each year," the researchers wrote.
Aside from the emotional trends, researchers discovered that dance and pop were the most successful genres of music and that there was a “clear downward trend” with the popularity of rock beginning in the early 2000s.
"So it looks like, while the overall mood is becoming less happy, people seem to want to forget it all and dance," Komarova wrote in an email.
It was also found that the "maleness" of songs - the frequency of male singers in popular music - had decreased during the last 30 years.
"Successful songs are characterised by a larger percentage of female artists compared to all songs," they wrote.
This discovery emerges at a time when the conversation around gender equality in the music industry is at its height, with men dominating as artists and songwriters.
The report was written by Komarova alongside with Myra Interiano, Kamyar Kazemi, Lijia Wang, Jienian Yang and Zhaoxia Yu.