Effects of Illuminance and Ambient Bedside Sounds on Pressure Pain Thresholds

Abstract

　The aim of this study was to experimentally assess the effects of environmental sensory stimuli, specifically illumination and ambient bedside sounds, on pressure pain thresholds under hospital-like conditions. Twenty-four healthy adults in their 20s and 30s were included. Pain was induced using the nail root pressure method. Four experimental conditions were created by combining two illuminance conditions (approximately 200 lx and no illuminance using an eye mask) and two bedside sound conditions (ambient sound at 50 dB and no sound).
　Pressure pain thresholds were evaluated using the magnitude estimation method, in which participants applied pressure corresponding to a subjective pain intensity of "5," based on their individual maximum pain. Pressure values were normalized and expressed as percentages of maximum pressure (%MP) . Two-way repeated-measures analysis of variance was performed with illuminance and bedside sounds as within-subject independent variables.
　The results demonstrated a significant interaction between illuminance and bedside sounds. Specifically, bedside sounds significantly increased pressure pain thresholds only when illuminance was present. Although a significant main effect of bedside sounds was also observed, this effect likely reflected the contribution of the sound-present condition under illuminance.
　These findings suggest that the effects of ambient bedside sounds on pain perception are modulated by visual environmental conditions, and that their combined presentation with moderate illuminance may enhance pain threshold elevation. From a clinical perspective, optimizing the sensory environment of hospital rooms by incorporating appropriate ambient sounds together with adequate illuminance may offer a feasible nonpharmacological approach to support pain management.