Registered Report Stage I: Effects of continuous overnight pink noise on sleep quality in ICU patients: An assessor-blind randomized controlled trial

Background Sleep disturbance is common in intensive care unit (ICU) patients. Continuous pink noise may reduce the perceptual contrast of environmental sounds, but its effects on sleep quality in ICU patients remain uncertain. Objective This Stage 1 Registered Report proposes a randomized controlled trial to evaluate whether continuous overnight pink noise improves patient-reported sleep quality in ICU patients. Methods This single-center, assessor-blind, parallel-group trial will randomize 56 adult ICU patients equally to continuous overnight pink noise or standard care. Pink noise will be delivered through a bedside directional speaker at a nominal calibrated level of 45 dB(A), from 21:00 to 06:00, for up to seven ICU nights, subject to prespecified safety and discontinuation criteria. The primary outcome is the Richards-Campbell Sleep Questionnaire (RCSQ) total score, assessed each available morning. Secondary outcomes are state anxiety and pain. Heart rate variability measured during two prespecified 30-minute nocturnal windows and sedative and analgesic exposure are exploratory outcomes. Planned analysis Participants will be analyzed according to randomized assignment. A linear mixed-effects model will estimate the adjusted between-group difference in RCSQ scores averaged across Nights 1–7 while participants are alive and remain in the ICU. Night will be categorical, with baseline APACHE II score included as a prespecified covariate. Secondary tests will use Holm correction. Reason-specific handling of missing data and sensitivity analyses are prespecified. Expected contribution This trial will evaluate a standardized acoustic intervention for ICU sleep disturbance, with exploratory physiological findings interpreted within the sampled measurement windows.