Fig. 1.

Scatterplots showing partial correlations in Study 1 between sleep-related-earworm frequency and (a) music listening/engagement, (b) global sleep quality, (c) daytime sleepiness, and (d) vulnerability to insomnia. Overlapping data points are plotted darker. Solid lines show best-fitting regressions, and error bands represent 95% confidence intervals. Partial correlations controlled for gender, and the reduced sample size in (b) reflects missing data. Music listening/engagement was measured with Goldsmiths Musical Sophistication Index (Gold-MSI), global sleep quality was measured with the Pittsburgh Sleep Quality Index (PSQI), daytime sleepiness was measured with the Stanford Sleepiness Scale (SSS), and vulnerability to insomnia was measured with the Ford Insomnia Response to Stress Test (FIRST).