Do lyrics and familiarity of music listened to at night affect sleep quality and insomnia?

Difficulty getting to sleep is a frequent problem in society with a range of consequences for both physical and mental health. Listening to music before sleep has been shown to provide the potential to help improve sleep quality. However, the familiarity of the music and the presence of lyrics have the potential to alter the effectiveness of pre-sleep music, but remain largely unexplored to date. 169 participants were randomly assigned to one of four conditions: familiar music with lyrics, familiar music without lyrics, unfamiliar music with lyrics, and unfamiliar music without lyrics. In each condition participants were required to listen to this music for seven consecutive nights while they fell asleep. At the beginning and the end of the study, participants completed two self-report questionaries that measured their quality of sleep (PSQI) and insomnia (ISI). As expected, sleep quality and insomnia severity generally improved after 7 days of listening to music. Findings suggest that familiar music improved sleep quality (but not insomnia) more without lyrics, while unfamiliar music improves sleep quality more if lyrics are present. These findings contribute to an enhanced understanding of how to use music for aiding sleep in a more effective way.