The impact of sound intervention on sleep quality and stress levels in college students: a randomized controlled trial

Introduction To assess the effectiveness of interventions combining pink noise or binaural beats with pure music in improving sleep quality and reducing perceived stress among college students, and to preliminarily investigate their effects on morning salivary cortisol levels. Methods Using a three-group randomized controlled design, 66 college students with poor sleep quality (PSQI score >7) were randomly assigned to a pink noise + pure music group, a binaural beats + pure music group, or a control group. The intervention group received a 30-min audio intervention at bedtime for 4 consecutive weeks, 5 nights per week. Morning salivary cortisol concentrations were measured at baseline, week 2, week 4, and the week-6 follow-up. Perceived stress and sleep quality were assessed using the PSS and PSQI, respectively. Results Generalized estimating equation analyses revealed significant time, group, and time-by-group interaction effects for both PSS and PSQI scores ( p < 0.05). The binaural beats + pure music group was more effective at reducing stress. Morning salivary cortisol concentrations showed only a significant main effect of time ( p < 0.05), with no significant group differences. Discussion A 4-week bedtime audio intervention effectively improved sleep quality and reduced perceived stress. Binaural beats combined with pure music appeared to be more effective in reducing perceived stress, but this benefit was not reflected in peak salivary cortisol levels measured 30 min after awakening. However, cortisol measurements obtained at a single daily time point are insufficient to infer a short-term modulatory effect of the intervention on basal hypothalamic–pituitary–adrenal (HPA) axis activity.