Preliminary evidence: the stress-reducing effect of listening to water sounds depends on somatic complaints: A randomized trial

BACKGROUND: Listening to natural sounds is applied in health contexts in order to induce relaxation. However, it remains unclear whether this effect is equally efficacious in all individuals or whether it depends on interindividual differences. Given that individuals differ in how they are impaired by somatic complaints, we investigated whether somatic complaints moderate the stress-reducing effect of listening to water sounds. METHODS: Sixty healthy women (M(age) = 25 years) were randomly allocated to 3 different conditions (listening to water sounds, a relaxing piece of music, or no auditory stimulus: n = 20 per condition) for 10 minutes before they were exposed to a standardized psychosocial stress task. Salivary cortisol was assessed before, during, and after the stress task. For binary logistic regression analyses, participants were divided into 2 groups: 1 group with a high salivary cortisol release and 1 group with low cortisol release. The Freiburg Complaints Inventory was used to assess occurrence of somatic complaints. RESULTS: A significant moderating effect of somatic complaints on cortisol secretion was found in the group listening to water sounds (χ(2)(1) = 5.87, P < .015) but not in the other 2 groups, explaining 35.7% of the variance and correctly classifying 78.9% of the cases. CONCLUSION: The stress-reducing effect of listening to water sounds appears to depend on the occurrence of somatic complaints. This effect was not found in the music or silence condition. Individuals with somatic complaints may benefit from other, potentially more powerful forms of stress-reducing interventions, that is, combinations of visual and auditory stimuli. TRIAL REGISTRATION: not applicable (pilot study)