If you listen to music before bedtime, your brain continues processing the melody while you sleep, according to research published in the journal Psychological Science. A sleep lab study found that around one quarter of participants who listened to familiar songs before bedtime awoke during the night with the melody “stuck” in their heads. This spontaneous replaying of music in the mind — a phenomenon called an earworm — was associated with lower sleep quality.
The authors of the study note that someone is more likely to experience an earworm, a form of involuntary musical imagery, after listening to music with a fast tempo and specific melodic contours. Young people are listening to music more than ever, and the music industry is dominated by these types of upbeat songs that are made to be catchy. Given that many people listen to music to fall asleep, the researchers wanted to investigate whether listening to music around bedtime might trigger earworms and whether these earworms might affect quality of sleep.
“I never thought about earworms until I taught a Cognition course and learned that there’s a subfield dedicated to understanding why we experience songs stuck in our minds,” said study author Michael K. Scullin, an associate professor at Baylor University and principal investigator at the Sleep Neuroscience and Cognition Lab.
“As a sleep scientist, I was curious whether having an earworm at bedtime would affect sleep. Some of us thought it would harm sleep because earworms can sometimes be irritating. Others in the lab thought it would help sleep, because maybe the earworm would distract you from ruminative thoughts. It was a fun series of studies to test these competing viewpoints.”
In an initial, cross-sectional study among 199 Americans, around 33% of participants reported experiencing earworms around bedtime — either while trying to fall asleep, while waking in the night, or upon waking in the morning. Participants who reported more frequent music listening were more likely to experience these sleep-related earworms. Interestingly, greater music listening was associated with worse sleep, and this effect was mediated by the frequency of sleep-related earworms. Remarkably, participants with sleep-related earworms scored 54% worse on the Pittsburgh Sleep Quality Index.
Next, Scullin and his team conducted a sleep lab experiment among a sample of 48 young adults. The experiment involved a polysomnography test, which recorded subjects’ brain waves, blood oxygen levels, breathing patterns, heart rate, and eye and body movements overnight. Importantly, about half an hour before going to sleep, all participants were randomly assigned to listen to either instrumental or lyrical versions of three well-known pop songs.
The next morning, about ten minutes after waking, the participants were asked whether they currently had a “sound, song, or melody” stuck in their heads. They were also asked whether they had experienced a song being stuck in their heads while trying to fall asleep, while waking in the night, or upon waking in the morning.
According to the polysomnography results, participants who listened to the instrumental music experienced significantly worse sleep compared to those who heard the lyrical music — as demonstrated by poorer sleep efficiency and more trouble falling asleep. People who had sleep-related earworms also had worse sleep, as evidenced by poorer sleep efficiency, more trouble falling asleep, more waking up in the night, and “a shift from deeper sleep toward lighter sleep.” Notably, this effect was unique to earworms experienced around bedtime, and the same effect was not found for earworms experienced about ten minutes after getting up.
Similar to the first study, about a quarter of participants said they woke from sleep with an earworm, a finding the authors say is striking since participants had not heard music for 8 hours and there was nothing in the environment to spark involuntary musical imagery.
“We conducted two studies, one that was survey based and another involved bringing people into a sleep laboratory and experimentally inducing earworms. Our findings kept pointing to the same conclusion: the more you listen to music, the more likely you are to catch an earworm at night, which then leads to a greater likelihood of sleep problems,” Scullin told PsyPost.
In a final study, the researchers analyzed the electroencephalography (EEG) data from the sleep lab study and found evidence of greater frontal slow oscillations in sleepers with sleep-related earworms. These frontal slow oscillations have also been reported in memory consolidation studies, suggesting that earworms are the result of the brain spontaneously replaying melodies during sleep to help transfer the information into cortical networks.
“We found that 1/4 of people reported having an earworm either in the middle of the night or immediately upon awakening in the morning. That fascinated us. Why should someone have a song stuck in their head if they haven’t listened to music or been exposed to other environmental cues for many hours?” Scullin said.
“We think this must reflect a memory consolidation process — the musical melody is being reactivated at night. Interestingly, the same brain activity signature of memory consolidation during sleep (frontal slow oscillation activity) was observed to be elevated in individuals who reported earworms at night. Still, we don’t yet have an answer to why memory consolidation of a song should result in poorer sleep quality.”
Together, the results suggest that musical processing continues while sleeping, and that listening to familiar music before bedtime may not be conducive to good sleep.
“There are lots of ‘fads’ for improving sleep,” Scullin added. “But it’s important to remember that obtaining great sleep begins with prioritizing sleep. Picking an earlier bedtime, and consistently sticking to it, is one of the most important things a person can do to feel well rested and to flourish during daytime hours. We’re also developing a website to promote better sleep habits: SleepIsGood.com”
The study, “Bedtime Music, Involuntary Musical Imagery, and Sleep”, was authored by Michael K. Scullin, Chenlu Gao, and Paul Fillmore.