The Effects of White Noise for Adult Patients' Sleep Quality in Intensive Care Unit: a Randomized Controlled Trial
Phase: NA
Conditions: Sleep
Sponsor: Chang Gung Memorial Hospital

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Study protocol 
NCT number: 05785130 
Date of the document: 2 March 2023 
Title: The Effects of White Noise for Adult Patients' Sleep Quality in Intensive 
Care Unit. 
Background and objective: Sleep is one of the basic physiological needs for 
humans. According to the American National Sleep Foundation, the 
recommended sleep duration for adults (18-64 years old) is 7-9 hours per day, 
while for older adults (65 years and above), it is 7-8 hours per day (Hirshkowitz 
et al., 2015). However, sleep disturbances are common among intensive care 
unit (ICU) patients. It is estimated that more than half of ICU patients report 
experiencing sleep disorders during their stay (Blissitt, 2016). A study by 
McKinley et al. in 2012 tracked 164 critically ill patients, aged 18 and above, 
who were in the ICU for more than 48 hours and used a ventilator for more than 
24 hours. The study found that one week after transferring out of the ICU, 50% 
of patients still reported moderate to severe sleep disturbances, and one-third 
continued to experience moderate to severe sleep disturbances 26 weeks after 
discharge. This indicates that sleep disorders not only occur during ICU 
admission but may also persist after discharge. 
There are many factors contributing to sleep disorders in ICU patients, 

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including pain, light, and the severity of illness. Noise is one of the factors 
leading to sleep disturbances in critically ill patients (Pisani, 2015). According 
to the World Health Organization's recommendations, daytime environmental 
noise should be below 45 decibels, and nighttime sleep noise should be below 
35 decibels (World Health Organization, 2010). However, ICUs are filled with 
the sounds of operating medical equipment and alarm signals due to treatment 
requirements. A study by Darbyshire & Young (2013) measured the noise 
levels in five adult ICUs and found that the noise level exceeded 45 decibels 
throughout the day, with the lowest noise level at 4 a.m. being 51 decibels, 
which is still higher than the WHO recommendation. Furthermore, noise levels 
exceeding 85 decibels occurred 16 times during the night. A 2007 study by 
Uğraş and Öztekin, which used a questionnaire to investigate the causes of 
sleep disturbances in patients in a neurosurgical ICU, found that 78.6% of the 
84 patients reported sleep disturbances, and 57.6% of them attributed the 
disturbances to environmental noise. Sudden loud noises not only cause sleep 
interruptions but also increase the number of awakenings, leading to sleep 
disorders (Devlin et al., 2018; Reuter-Rice, 2020). Once sleep disturbances 
occur, they negatively affect the immune system, respiratory function, 
metabolic functions, and cardiovascular health, while also causing 
psychological stress and negative emotions (Reuter-Rice, 2020; Sterniczuk et 

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al., 2014). Over time, these disturbances affect the recovery of critically ill 
patients, leading to extended hospital stays, increased medical costs, and higher 
mortality rates (Altman et al., 2018; Pisani, 2015). Furthermore, sleep disorders 
can impair cognitive functions such as memory, attention, and reaction time, 
increasing the risk of delirium (Van et al., 2009). Thus, sleep issues in ICU 
patients require urgent attention.  
Currently, the treatment of sleep disorders in ICU patients still primarily 
involves medication, but cognitive decline, drug tolerance, and drug 
dependence may lead to negative effects on sleep. Therefore, many 
international studies have explored non-pharmacological interventions to 
improve ICU patients' sleep, such as reducing light and noise stimuli, 
minimizing nighttime disturbances, or teaching relaxation techniques. Among 
these, white noise intervention is one approach to reduce light and sound 
stimulation. The purpose of white noise is to create a consistent sound with 
fixed frequencies and tones, which can raise the hearing threshold during 
nighttime sleep, reducing the frequency of being awakened by sudden loud 
noises, and thereby enhancing sleep quality through masking effects 
(Farokhnezhad Afshar et al., 2016). 
White noise interventions have often used white or pink noise in research, 
typically targeting newborns, students, or healthy adults. For example, a study 

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on white noise in a cardiac ICU found that exposure to 40-50 decibel noise 
between 8-9 p.m. and 11 p.m.-12 a.m. for one hour each night for three days 
significantly improved sleep quality compared to the control group 
(Farokhnezhad Afshar et al., 2016). This suggests that the effectiveness of 
white noise interventions in improving ICU patients' sleep quality is 
inconsistent, possibly due to differences in the duration and timing of the 
intervention. Furthermore, sleep disturbances during the night in the ICU are 
unpredictable, and short intervention periods may not be sufficient to protect 
patients from sudden noise events that occur outside the intervention hours. 
Many studies on white noise in adult ICUs use the Pittsburgh Sleep Quality 
Index to measure sleep quality, which assesses sleep over the past month. 
However, since critically ill patients are in the acute phase and their ICU stay is 
usually short, the Pittsburgh Sleep Quality Index may not accurately reflect 
their sleep condition during their ICU stay. Additionally, individuals may have 
preferences for different types of white noise, making it difficult to standardize 
the type of noise used in interventions. Therefore, the purpose of this study is to 
explore the effectiveness of white noise interventions on sleep quality in adult 
ICU patients. The aim is to utilize this low-cost, easy-to-implement, and 
accessible measure to block out ICU noise and improve the sleep quality of 
critically ill patients in the ICU. 

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Method: The inclusion criteria of this study as follows: (a) age must be greater 
than or equal to 20 years old, (b) admitted to the ICU and have been intubated 
for at least 24 hours, (c) awareness of people, time, and place without hearing 
impairment., (d) be able to communicate in writing., (e) the Glasgow Coma 
Scale(GCS) score must be equal to or greater than 11(with a vocal response of 1 
in the patient post-endotracheal tube placement). The exclusion criteria of this 
study as follows: (a)history of insomnia, Alzheimer's disease, or depression, (b) 
routine use of sedative-hypnotic drugs (opioids, benzodiazepines, 
non-benzodiazepines, antihistamines, and melatonin) before admission, (c) 
post-operation in the operating room before ICU admission, (d) intensive care 
delirium screening checklist(ICDSC) score of at least 4 or Confusion 
Assessment Method for the Intensive Care Unit (CAM-ICU) positive. 
Sample: The sample size for this study is calculated using G*Power 3.1, with 
an effect size set at 0.25 (Kotrlik & Williams, 2003), α = 0.05, and power = 0.8. 
The minimum required sample size is 58 participants. In statistical analysis, a 
sample size of 30 is often considered the threshold for a large sample , the total 
sample size will be 60 participants, with 30 participants in the experimental 
group and 30 participants in the control group. 
Study interventions 
This study adopts a convenience sampling method and will be conducted 

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in the Fifth Department of Internal Medicine ICU at Kaohsiung Chang Gung 
Memorial Hospital. The study groups are set as follows: the white noise group 
will receive white noise intervention, while the conventional treatment group 
will receive standard care. The total sample size of 60 participants will be 
divided into 6 blocks of 10 participants each, with random assignment 
generated by a computer. Upon admission to the ICU, patients who meet the 
inclusion and exclusion criteria will be selected. The principal investigator will 
fully explain the study's purpose and procedures to the patients, and once 
informed consent is obtained, the recruitment process will begin. On the first 
day of enrollment, participants will complete a baseline assessment using the 
VAS sleep quality scale (T0). Random assignment will then allocate 
participants to either the Treat (white noise) group or the Control (standard care) 
group based on the generated block sequence. 
For the white noise group, in addition to receiving standard care, white 
noise will be introduced from 11 p.m. to 6 a.m. the following morning. A 
noise-reducing sleep aid device will be placed at the corner of the bedside 
cabinet, and a decibel meter will be positioned near the patient's head. The 
volume of the noise-reducing sleep aid device will be controlled between 40-50 
decibels. According to a study by Van et al. in 2009, up to 90% of delirium 
occurs on the third day of ICU admission, so the intervention will be applied 

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continuously for three nights. The control group will receive standard care. 
Both groups will complete the VAS sleep quality scale at 6 a.m. on the first day 
after intervention (T1), the third day (T2), and the fifth day (T3). The total 
number of assessments will be four, each taking approximately 5 minutes. 
Outcome measurements:The Verran and Snyder-Halpern Sleep Scale (VSHSS) 
was initially developed by Snyder-Halpern & Verran in 1989 to measure the 
sleep quality of hospitalized patients from the previous night. The internal 
consistency reliability was found to be 0.82. The original scale consisted of four 
subscales: sleep fragmentation, sleep disturbance, effective sleep, and 
compensatory sleep. In 1996, Simpson et al. revised the scale to include three 
subscales: sleep disturbance, effective sleep, and compensatory sleep. Tranner 
et al. tested the scale in 2003 with 110 hospitalized and surgical patients, and 
the Cronbach's α values for the subscales of sleep disturbance, effective sleep, 
and compensatory sleep were 0.86, 0.80, and 0.63, respectively. In 2007, Fang 
and Wang translated this scale, and the Cronbach’s α values for sleep 
disturbance, effective sleep, and compensatory sleep were 0.90, 0.72, and 0.64, 
respectively. The overall internal consistency was 0.84, and the Content Validity 
Index (CVI) was 1.0. 
The scale consists of 15 items, each scored on a 0-100mm visual analog 
scale, where 0 represents the lowest score and 100 represents the highest. The 

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sleep disturbance section contains 7 items, with a total score range from 0 to 
700. A lower score indicates more severe sleep disturbance. The effective sleep 
section contains 4 items, with a total score range from 0 to 400. A lower score 
indicates less effective sleep. The compensatory sleep section contains 4 items, 
with a total score range from 0 to 400. A lower score indicates a greater need 
for compensatory sleep. Since the original author of the scale has passed away, 
the version of the Verran and Snyder-Halpern Sleep Scale used in this study has 
been translated and authorized by the publisher. 
Statistical Methods: Descriptive Statistics: Personal demographic data and 
disease characteristics of the study participants will be analyzed. Categorical 
variables will be presented as frequencies and percentages, while continuous 
variables will be expressed as means and standard deviations. 
Inferential Statistics:Independent samples t-tests or chi-square tests will be 
used to compare the homogeneity of sleep quality and demographic data 
between the white noise group and the general care group before the 
intervention. 
Independent samples t-tests will be used to compare the differences in 
sleep quality pre- and post-intervention between the white noise group and the 
general care group. 
Generalized Estimating Equations (GEE) will be used to compare the 

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effects of the white noise group and the general care group under the factors of 
group, time, and the interaction between group and time. 
Ethical considerations: Ensuring Non-Disclosure of Participants' Identity and 
Information: A research code will be used to represent each participant's 
identity during the study, ensuring that the participant's name, ID number, 
address, medical record number, or any other personal information will not be 
disclosed during the research process. 
Confidentiality of Participant Data and Diagnosis: The research 
investigator will maintain confidentiality and carefully protect the privacy of 
participants' data. Before the study begins, participants will be informed that the 
questionnaires they complete and the data collected will be encoded and kept 
confidential, solely for the purposes of this study. These data will be securely 
stored in a locked cabinet by the principal investigator, and only the study team 
will have access to them. No external parties will have access to the data. After 
the study is completed, the data will be destroyed five years later and will not 
be retained. If at any point during the study a participant experiences discomfort, 
they have the right to withdraw at any time without affecting the treatment and 
rights they are entitled to. 
Confidentiality in Publication of Results: If the study results are published, 
the identity of the participants will remain confidential. The researcher will 

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explain the study's purpose and procedures to participants before obtaining their 
consent and having them sign the informed consent form. In future academic 
publications, no identifying information such as the research institution or 
participant codes will be included.