The study contradicts the established opinion about the beneficial effect of music on those falling asleep. Scientists have objectively shown that catchy melodies can disrupt sleep for at least some people. The work is published in Psychological Science.
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Music can affect the onset of sleep and the quality of sleep. Scientists usually report its positive effects. For example, in one study, adults experienced improved sleep after 45-minute sessions of listening to music before falling asleep. Younger school-aged children sleep better after soothing melodies.
The American Sleep Research Foundation points out that personal preferences can play a role in the effect of music on sleep. In general, it should be relaxing music or pieces that help you fall asleep earlier. It is desirable that its rhythm should not exceed 60-80 beats per minute.
The positive effect of music on sleep is mainly known from studies in which data was obtained from the participants' own words. In a new study, scientists assessed sleep objectively. Its authors showed that for some people, music can have a completely opposite – that is, negative – effect.
“Our brains continue to process music even when it’s not playing, including while we sleep. Everyone knows that listening to music is enjoyable. Young people often listen to it before bed. But sometimes there’s too much of a good thing. The more you listen, the more likely you are to pick up on an obsessive tune that continues into your sleep. When that happens, your sleep quality can suffer,” said Michael Scullin, a professor at Baylor University and co-author of the study.
The first part of the study involved 209 people. They answered a series of questions about their sleep quality and music listening habits. In particular, they described how often melodies cling to them, “popping up” while falling asleep, night and morning awakenings.
The experimental part of the study included 50 people. Before going to bed, they were played catchy, memorable pieces of music: either popular songs or instrumental versions. The volunteers slept in a laboratory, and their sleep characteristics were recorded using polysomnography. Among other things, it includes recording an electroencephalogram and cardiogram, recording eye movements and muscle contractions. These indicators allow us to judge the quality of sleep with high confidence.
The participants told the scientists whether any of the melodies played “sticked” to them. The researchers then compared this information with the sleep quality data.
People who continued to play the intrusive melodies in their memory were more likely than others to have difficulty falling asleep, they were more likely to wake up from nightmares and spent more time in a state of light sleep. The electroencephalogram showed that these people had a phenomenon of memory consolidation in sleep. That is, temporary memory was spontaneously activated during sleep to turn into its longer types.
“We expected that people might be influenced by intrusive melodies at night. But we certainly didn’t know that they might report regular awakenings due to nightmares that accompany this melody in memory. We found this phenomenon both in the survey and in the experiment,” Scullin said.
Scullin added that almost everyone believes that music improves sleep. However, it is now clear that even instrumental music can worsen it in many people. Moreover, it was precisely this music that was more easily “attached” to the study participants.