Sleep disruption is common in adult intensive care unit (ICU) patients and is often worsened by environmental noise and nighttime care activities. Poor sleep may negatively affect recovery and well-being.

This single-center, three-arm randomized controlled trial will evaluate the short-term effects of two non-pharmacological interventions-(1) pink-brown noise masking and (2) a quiet time intervention-on objective sleep parameters in adult ICU patients, compared with standard care.

Sleep outcomes will be measured using actigraphy-based wearable monitoring, including total sleep time, sleep efficiency, sleep onset latency, wake after sleep onset, and number of awakenings. Results are expected to support evidence-based nursing approaches to improve sleep in ICU patients.

This study is designed as a single-center, three-arm, parallel-group randomized controlled clinical trial to evaluate the short-term effects of environmental acoustic masking and a quiet night intervention on objective sleep parameters in adult intensive care unit (ICU) patients.

Sleep disturbance is highly prevalent among critically ill patients due to environmental factors such as excessive noise, continuous light exposure, frequent nursing interventions, alarm sounds, mechanical ventilation, pain, anxiety, and disease-related physiological stress. These factors lead to fragmented and superficial sleep, disruption of the sleep-wake cycle, and are associated with adverse clinical outcomes including delirium, immune dysfunction, hemodynamic instability, prolonged ICU stay, and increased morbidity.

The study includes three groups:

1. an acoustic masking intervention group,
2. a quiet night intervention group, and
3. a standard care control group.

The acoustic masking group will receive low-frequency, nature-based sound exposure prior to sleep onset, followed by earplug use throughout the night. The quiet night group will receive environmental noise and light reduction measures supported by earplugs and an eye mask. The control group will receive standard ICU care without additional sleep-promoting interventions.

Objective sleep parameters will be measured using wrist-worn actigraphy over a single night (23:00-06:00). Primary sleep outcomes include total sleep time, sleep efficiency, sleep onset latency, wake after sleep onset, and number of nocturnal awakenings. Actigraphy is selected as a feasible, non-invasive, and validated method for sleep assessment in critically ill populations.

Prior to the main trial, a pilot phase will be conducted to assess the feasibility of the study procedures, the applicability of the interventions, the functionality of data collection methods, and the variability of outcome measures required for sample size estimation. The pilot phase will include all three study arms and will follow the same methodology, eligibility criteria, intervention protocols, and outcome assessments as the main trial. Participants enrolled in the pilot phase will constitute an independent sample and will not be included in the final analysis of the main trial.

Data obtained from the pilot phase will be used solely for methodological refinement and sample size calculation. Findings from the pilot phase may be disseminated separately.

The study aims to generate evidence for low-cost, non-invasive, nurse-led environmental interventions that can be integrated into routine ICU care to improve sleep quality in critically ill patients.

Inclusion Criteria:

• Inclusion Criteria:
• Adults aged 18 years and older
• Patients admitted to the adult intensive care unit
• Expected ICU stay of at least one night
• Ability to tolerate non-invasive sleep-related interventions (earplugs, eye mask, or acoustic masking)
• Informed consent obtained from the patient or legally authorized representative

Exclusion Criteria:

Exclusion Criteria:

• Severe hearing impairment preventing use of acoustic interventions
• Severe cognitive impairment or coma preventing sleep assessment
• Use of continuous deep sedation
• Diagnosed sleep disorders requiring pharmacological treatment
• Skin conditions preventing use of wrist-worn actigraphy

Individual participant data will not be shared publicly. De-identified data may be made available upon reasonable request to the corresponding investigator, subject to ethical approval and institutional regulations.

Outcome assessors and data analysts are blinded to group allocation. Participants and care providers are not blinded due to the nature of the interventions.