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Effects of earplugs and eye masks on nocturnal sleep, melatonin and cortisol in a simulated intensive care unit environment

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  • The Second Affiliated Hospital of Fujian Medical University

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Environmental stimulus, especially noise and light, is thought to disrupt sleep in patients in the intensive care unit (ICU). This study aimed to determine the physiological and psychological effects of ICU noise and light, and of earplugs and eye masks, used in these conditions in healthy subjects. Fourteen subjects underwent polysomnography under four conditions: adaptation, baseline, exposure to recorded ICU noise and light (NL), and NL plus use of earplugs and eye masks (NLEE). Urine was analyzed for melatonin and cortisol levels. Subjects rated their perceived sleep quality, anxiety levels and perception of environmental stimuli. Subjects had poorer perceived sleep quality, more light sleep, longer rapid eye movement (REM) latency, less REM sleep when exposed to simulated ICU noise and light (P < 0.05). Nocturnal melatonin (P = 0.007) and cortisol secretion levels (P = 0.004) differed significantly by condition but anxiety levels did not (P = 0.06). Use of earplugs and eye masks resulted in more REM time, shorter REM latency, less arousal (P < 0.05) and elevated melatonin levels (P = 0.002). Earplugs and eye masks promote sleep and hormone balance in healthy subjects exposed to simulated ICU noise and light, making their promotion in ICU patients reasonable.
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RESEARC H Open Access
Effects of earplugs and eye masks on nocturnal
sleep, melatonin and cortisol in a simulated
intensive care unit environment
Rong-fang Hu
1
, Xiao-ying Jiang
1*
, Yi-ming Zeng
2
, Xiao-yang Chen
2
, You-hua Zhang
3
Abstract
Introduction: Environmental stimulus, especially noise and light, is thought to disrupt sleep in patients in the
intensive care unit (ICU). This stud y aimed to determine the physiological and psycho logical effects of ICU noise
and light, and of earpl ugs and eye masks, used in these conditions in healthy subjects.
Methods: Fourteen subjects underwent polysomnography under four conditions: adaptation, baseline, exposure to
recorded ICU noise and light (NL), and NL plus use of earplugs and eye masks (NLEE). Urine was analyzed for
melatonin and cortisol levels. Subjects rated their perceived sleep qu ality, anxiety levels and perception of
environmental stimuli.
Results: Subjects had poorer perceived sleep quality, more light sleep, longer rapid eye movement (REM) latency,
less REM sleep when exposed to simulated ICU noise and light (P < 0.05). Nocturnal melatonin (P = 0.007) and
cortisol secretion levels (P = 0.004) differed significantly by condition but anxiety levels did not (P = 0.06). Use of
earplugs and eye masks resulted in more REM time, shorter REM latency, less arousal ( P < 0.05) and elevated
melatonin levels (P = 0.002).
Conclusions: Earplugs and eye masks promote sleep and hormone balance in healthy subjects exposed to
simulated ICU noise and light, making their promotion in ICU patients reasonable.
Introduction
Sleep disruption is common in ICU patients and has
been characterized by several studies using polysomno-
graphy (PSG) [1-3]. Adverse consequences of sleep dis-
ruption include impaired immune function, decreased
inspiratory muscle endurance, negatively affec ted wean-
ing fr om mechanical ventil ation, and a possible associa-
tion with delirium and severe morbidity [4,5]. The
causes of sleep disruption in the ICU are multifactorial.
The ICU environment is thought to be an important
factor in sleep disruption [6].
Numerous studies have fo und excessive noise levels in
the ICU, often with nighttime peaks of more than 80 dB
(A) [5,7]. In a ddition, subjective and objective studies
both demonstrate that patients have been disturbed by
ICU noise [1,8-10]. Light ex posure is another important
sleep dis ruptor in ICU settings. Reported nocturnal illu-
mination in ICUs varies widely, with mean m aximum
levels of 5 to 1400 lux [5,11]. Light exposure is the pri-
mary external cue for circadian rhythm. In addition,
nocturnal melatonin secretion can be acutely suppressed
by light, and 100 lux is sufficient to impact nocturnal
melatonin secretion [12]. Throughout the past decade,
evidence has been accumulating for the altered secretion
of melatonin in ICU patients. ICU patients suffer from a
severe lack of sleep associated with loss of the nocturnal
melatonin secretion pattern [13,14]. Therefor e, effective
interventions to promote sleep in ICU patients are
urgently needed.
Despitemanyclaimsthattheuseofnoisereduction
and lighting practice in an intensive care environment
may improve the patients sleep quality, there have been
few objective studies to evaluate the effects of these
interventions [15-17]. Most research in this area has
focused purely on noise reduction and not explored the
combined effects of ICU noise and light factors on
* Correspondence: xiaoyj320@163.com
1
School of Nursing, Fujian Medical University, Jiaotong Road 88, Fuzhou,
350004, PR China
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any medium, provid ed the original wor k i s properly cited.
physiological and psychological outcomes, including
sleep architecture, perceived sleep quality and hormone
secretion (melatonin and cortisol). No studies have yet
evaluated the effects of earplugs and eye masks on the
sleep of ICU patients as measured by PSG and hormone
secretion.
We hypothesized that patients sleep is disrupte d by
the noise and light in the ICU, accompanied by
impaired nocturnal melatonin secretion and elevated
cortisol secretion. Earplugs and eye masks worn during
exposure to a sim ulated ICU environment may improve
sleep and protect nocturnal melatonin and cortisol
secretion. To test this hypothesis, an experimental study
was conducted in a sleep laboratory.
Materials and methods
Research design
This study used a repe ated measures design. Four noc-
turnal nine-hour (10:00 p.m. to 7:00 a.m.) periods of
sleep were measured, including adaptation, baseline,
exposure to recorded ICU noise and light (NL), and NL
plus use of earplugs and eye masks (NLEE). All subjects
(n = 14) underwent a total of four overnight PSG.
To minimize order effects, earplugs and eye masks
were randomly worn on either the third ( n = 7) or
fourth (n = 7) night (Figure 1). For each subject, study
nights were spaced one day apart to avoid delay effects.
Subjects were asked to keep a sleep diary to record their
rest, activity and diet during the study period.
Subjects were asked to provide two nocturnal (10:00 p.m.
to 7:00 a.m.) urine samples, during base, NL and NLEE
nights. Urine levels of melatonin sulfate and cortisol were
determined by ELISA and radioimmunoassay (RIA),
respectively.
All s ubjects completed a sleep scale and the Chinese
version of the Spielberger State Anxiety I nventory (SAI)
[18] at 7:30 a.m. after every experimental night to record
perceived sleep quality and anxiety levels, respectively.
The study was performed at the Sleep-breath D isor-
ders Center at the Second Affiliated Hospital, Fujian,
China. The study design was approved by the research
ethics boards of the hospital and the Fujian Medical
University.
Subjects
Subjects were in cluded in the study if they were non-
smokers, older than 18 years of age, had no hearing pro-
blem as determined by a hearing screening t est , had no
sleep disorders, scores of 7 or less on the Pittsburgh
Sleep Quality Index (PSQI), had no history of night-shift
work i n the past three years and agreed t o abstain from
caffeine and alcohol for 12 h ours prior to each study
night. All provided written informed consent before
being enrolled in the study.
Figure 1 Study design.
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Subjects were excluded if PSG on the adaptation night
found any sleep disorder including s leep apnea, narco-
lepsy, chronic insomnia or restless leg syndrome. Female
subjects were excluded while they were menstruating.
Subjects were recruited by advertisements posted at
the Second Affiliated Hospital. Fourteen subjects were
enrolled in the study. Each was paid 200 Yuan Renminbi
at the end of the study.
Instruments
Recorded ICU noise
ICU noi se was cont inuously monitored for 24 hours
using a sound meter, model AWA5610D (AWAI, Hang-
zhou, China) i n five ICU environments: a surgical ICU
(SICU), a coronary care unit (CCU), a cardiac surgical
ICU (CSICU) and two medical ICUs (MICU). All had
noise levels far exceeding the 20 dB(A) at nighttime
recommended by the Guidelines of the Chinese Associa-
tion of Critical Care Medicine (2006)[19]. The SICU was
the loudest. The mean (standard deviation) noise value
in the SICU was 70.1 ± 11.9 dB(A), the peak noi se level
recorded was 95.3 dB(A), and the minimal noise value
was 51.4 dB(A) . Thereafter, ambient noise of the SICU
and CSICU were recorded digitally during a typical
weeknig ht shift and stored on computer for playback in
the sleep laboratory. The sound recording equipment,
modelICD-P320(SonyInc.,Tokyo,Japan)wasposi-
tioned at the bed of patients receiving mechanical venti-
lation. Simultaneous sound meter readings were taken
to ensure similar noise levels during playback in the
sleep laboratory.
Lighting conditions
Nighttime illum ination in fiv e ICU settings and the
sleep laborat ory were monitored by a light det ector,
model TES1332 (Taiwantes, Shenzen, China). In all set-
tings, light was provided by ceiling fluorescent lights.
The light detector was placed as close as possibl e to the
head of the bed of a patient receiving mechanical venti-
lation, but not so as to interfere with patient car e. L ight
measurements were taken every hour for 24 hours. Fi ve
ICUs maintained high mean night l ight levels ranging
between 50 and 238.6 lux, with highest mean nighttime
light levels in the SICU and CSICU. Mean nighttime
light levels in the sleep laboratory measured 100 lux
with the light on, and 5 lux with it off and the door to
the hallway shut. Therefore, the study used 100 lux to
simulate the ICU lighting condition.
Earplugs and eye masks
Subjects were instructed to wear earplugs with 29 d B
noise reduction rating (3 M Corporation, Beijing,
China) and eye masks during experimental night
NLEE. Subjects chose from three types of e ye masks
provided.
Polysomnography
Sleep was assessed by PSG using the Polysmith 2003
sleep acquisition and analysis system (Neurotronics, Gai-
nesville, FL, USA). The standard proc edure for sleep
measur ement described by Rechtschaffen and Kales [20]
was followed. Subjects were hooked up to record elec-
troencephalogram (EEG), eye movement and sub-mental
electromyogram (CHin EMG) in t he sleep lab oratory.
During NL and NLEE nights, recorde d ICU noise was
played and fluorescent lights turned on. A sound meter
wasplacedattheheadofthesubjects bed and the
recording time synchronized with t he sound meter to
ensure playback in a similar range of decibels to that
recorded. Electrode impedances were w ithin acceptable
limits (<10kQΩ). PSG equipment was located outside
the subjects room. Sleep variables (sleep period time,
sleep efficiency index, sleep onset latency, rapid eye
movement (REM) lat ency, arousa l index and percentage
of sleep in REM, stage one, two and three) were scored
manually by two scorers independently who were una-
ware of the experimental conditions, according to stan-
dardized criteria [20,21].
Melatonin and cortisol
Nocturnal urine was collected between 10 p.m. and
7 a.m. on baseline, NL and NLEE nights. The containers
were wrapped with black plastic t o protect the urine
from light. The amount was recorded and two samples
of each 2 ml were frozen to -20°C for later analysis.
Concentrations of 6-sulphatoxymelatonin (6-SMT), the
stable metabolite o f melatonin, were measured by
enzyme-linked immunometric assay (IBL, Hamburg,
Germany) in duplicate. Concentration of cortisol, a
stress-related hormone, was measured in another urine
sample b y RIA (Beijing North Instit ute of Biological
Technology, Beijing, China).
Subjective measurements
Subjective sleep quality was assessed by a visual analog
scale developed by the researchers based o n previous
scales [22]. Subjects evaluated their sleep quality on a
scale of 0 to 10 (0 = e xcellent, 10 = poor) at 7:30 a.m.
on the morning after every experimental night, with a
higher score indicating poorer habitual sleep quality.
State anxiety level was assessed at 7:30 a.m. on the
morning after every experimental nights. In our study,
Spielberger State Anxiety Inventory (SAI) was chosen
because it provides evaluation of state anxiety levels,
nam ely a temporary unpleasant emotional arousal in the
face of threatening demands or dangers [23]. Subjects
rated their feelings of anxiety on a four-point scale ranging
from one (almost never anxious) to four (almost always
anxious), a higher score indicating a higher anxiety level.
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On the morning after the NL night, subjects were
asked to assess the effects of simulated ICU noise and
light on sleep disruption, using a five-point scale ranging
from one (no disruption) to five (significant disruption).
Subjec ts were asked to evaluate the comfort, effective-
ness and ease o f use of e arplugs and eye masks on the
morning after the NLEE night, using a five-point scale
ranging from one (very uncomfortable, very unhelpful,
very awkward) to five (very comfortable, very helpful,
very ea sy to use) with low scores indicating a less plea-
sant experience.
Statistical analysis
Data were analyzed using SPSS version 16.0 (SPSS Inc.,
Chicago, IL, USA). Data for the adaptation night were
excluded from analysis bec ause the first night of sleep in
a sleep laboratory room with unfamiliar surroundings dif-
fers from sleep on subsequent nights [24]. All data were
expressed as mean ± standard deviation. One-way
repeated measures analysis of variance (ANOVA) were
used to determine differences in sleep variables, 6-SMT
and cortisol c oncentrations, perceived sleep quality and
anxiety levels during the three nights of the experiment.
Paired students t-test or non-parametric Wilcoxons
rank sum test were performed to evaluate the effect of
earplugs and eye mas ks on sleep variables and hormones
secretion during exposure to simulated ICU sound and
light where appropriate. Paired sample test was also used
to analyze differences in sound levels between NL and
NLEE nights. An alpha of 0.05 was considered significant.
Results
Fifteen healthy volunteers were recruited. One was
excluded due to evidence of significant insomnia.
A total of 14 subjects (8 females and 6 males, aged 21
to 70 years, mean 31.07 ± 15.64 years) completed the
study. The earplugs and eye masks were applie d easily
and remained intact during NLEE nights.
Sleep architecture
Results of sleep variables during basel ine, NL and NLEE
nights are shown in Table 1. Repeated measures
ANOVA showed that sleep architecture changed signifi-
cantly in percentage of REM sl eep (P =0.03),REM
latency (P = 0.02) and arousal index (P = 0.03) by condi-
tion. Contrast of sleep variables during exposure to
simulated ICU environment indicated tha t use of ear-
plugs and eye masks resulted in more REM sleep
(P = 0.005), shorter REM latency (P = 0.013) and fewer
arousals (P = 0.04; Figure 2).
Urinary excretion of 6-SMT and cortisol
Subjects urinary excretion during baseline, NL
and NLEE nights of 6-SMT and cortisol is shown in
Figures 3 and 4, respectively. Dif ferences in nocturnal
urinary secretion levels of 6-SMT (F =7.84,P =0.007)
and cortisol (F = 9.26, P = 0.004) were both significant.
Wilcoxons rank sum test showed significant differ-
ences in urine 6-SMT levels for NL and NLEE nights
(Z = -3.17, P = 0.002). But no difference was found in
urine cortisol levels for NL an d NLEE nights (Z = -1.47,
P = 0.14).
Subjective sleep quality and anxiety levels
The results of repeated measures ANOVA for subjective
sleep quality were significant (F = 20.6, P =0.00),but
those for anxiety levels (F =3.55,P =0.06)werenot
(Table 2).
Paired co ntrast showed use of earplugs and eye masks
improved perceived sleep quality notably (P = 0.001).
No difference was founded in anxiety levels between
the NL and NLEE nights (P = 0.28) by paired contrast,
although SAI scores showed interesting trends that
scores for NL night were highest.
Subjective perception of ICU environment and
interventions
On baseline, NL and NLEE nights, sound levels averaged
34 ± 0.6, 66.1 ± 4.2 a nd 66 ± 5.3 dB(A), respectively.
Paired contrast revealed no significant d ifference in the
noise l evel for NL a nd NLEE nights (P = 0.94). Table 3
shows t he subjective percept ion of t he effect of nois e
and light stimuli on sleep disruption on the NL night.
Eleven subjects perceived noise factor as a l ittle disrup-
tion but were able to fall asleep, two perceived n oise as
some disruption and were sometime s unable to fall
sleep, and one perceived light sleep and was easily awa-
kened by noise. There were eight, one and five subjects
perceived a little disruption but were a ble to fall asleep,
some disruption and was sometimes unable to f all
asleep, and light sleep and were easily awakened by con-
stant lighting, respectively.
Subjects evaluation of earplugs and eye masks is listed
in Table 4. Overall, they rated the devices highly, as very
comfortable, very helpful and very easy to use.
Discussion
These results support the notion that sleep and hor-
mones are both disturbed w ith exposure to simulated
ICU noise and light in healthy subjects. Use of earplugs
and eye masks improve subjective sleep quality
noticeably.
Our results confirm that subjects not only have poorer
perceived sleep quality, but also suffer from sleep dis-
ruption, measured as more light sleep, longer REM
latency and less REM sleep, with exposure to simulated
ICU noise and light levels. The results are similar to
those reported by Topf and Davis [25] and Wall ace and
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Table 1 Sleep architecture and study condition for subjects (n = 14)
Variable Baseline NL NLEE ANOVA P Contrast P
Time in bed (min) 539.7 ± 1.7 536.0 ± 15.9 536.0 ± 13.7 0.48 ——
Total sleep time (min) 456.0 ± 39.9 454.7 ± 41.8 475.1 ± 33.4 0.20 0.06
Sleep efficiency
Index
0.8 ± 0.1 0.8 ± 0.1 0.9 ± 0.0 0.12 0.09
REM% 10.9 ± 5.9 9.3 ± 4.3 12.9 ± 4.3 0.03 0.005
S1% 21.8 ± 10.4 23.4 ± 11.9 22.5 ± 9.7 0.80 0.67
S2% 43.9 ± 10.2 45.6 ± 10.3 43.5 ± 6.9 0.57 0.20
S3% 14.0 ± 6.8 11.6 ± 6.5 13.9 ± 5.6 0.30 0.11
Sleep onset latency (min) 22.3 ± 13.1 23.4 ± 16.6 15.4 ± 16.4 0.46 0.055
REM latency (min) 121.8 ± 47.0 146.9 ± 56.2 105.7 ± 47.0 0.02 0.013
Arousals index 13.0 ± 4.7 15.1 ± 6.2 12.2 ± 6.5 0.03 0.04
ANOVA, repeated measures analysis of variance; Contrast, paired students test or wilcoxons rank sum test of simulated ICU environment with and without
earplugs and eye masks; NL, recorded ICU noise and light exposure; NLEE, recorded ICU noise and light, subjects wore earplugs and eye masks; REM, rapid eye
movement.
Figure 2 Example of sleep histograms from the same subject.Lessrapideyemovement(REM)time,longerREMlatencyasexposure
to recorded ICU noise and light. NL, recorded ICU noise and light exposure; NLEE, recorded ICU noise and light, subjects wore earplugs
and eye masks.
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Figure 3 Urinary excretion of 6-SMT for different study conditions . Nocturnal urine 6-SMT concentration dur ing baseline, NL and NLEE
nights were 26.5 ± 20.0, 15.1 ± 13.6, and 22.3 ± 22.9 μg/kg, respectively. 6-SMT, 6-sulphatoxymelatonin; NL, recorded ICU noise and light
exposure; NLEE, recorded ICU noise and light, subjects wore earplugs and eye masks.
Figure 4 Urinary excretion of cortisol for different study conditions. Nocturnal urine cortisol concentration during baseline, NL and NLEE
nights were 2.0 ± 1.6, 4.0 ± 2.4, and 3.2 ± 2.1 μg/kg, respectively. NL, recorded ICU noise and light exposure; NLEE, recorded ICU noise and
light, subjects wore earplugs and eye masks.
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colleagues [16]. However, our study differs in that we
combined levels of noise and light i n a simulated ICU
environment in a sleep laboratory.
The I CU environment is not conducive to sleep. Sur-
vey studies showed that ICU patients co nsidered exces-
sive noise and bright lights noxious and disrupti ve [26].
Freedman and colleagues reported that nurse interven-
tions were mo re disrupt ive than noise or light [8].
Gabor and colleagues found that noise, light and patient
care activities accounted for less than 30% of nocturnal
arous als and awakenings [10]. Recently Cabello and col-
leagues reported noise accounte d for less than 15% o f
arousals and awakenings in mechanical ventilation
patients [27]. Therefore, noise has proved to be an
important sleep-disruptive factor and has negative phy-
siological and psychological effects on patients, although
it may not be responsible for the majority of the sleep
fragmentation. Recent emphasis has been on noise
reduction and encouraging the dimming of lights over-
night in ICU settings, but control of noise is not always
possible and light s are always present in critical care for
patient observations and patient care ac tivities. There-
fore, we hypothesized t hat use of earplugs and eye
masks may have benefits in some ICU patients with
regards to sleep disturbances.
The tolerability of these interventions is critical. Most
healthy subjects rated earplugs as comforta ble and easy
to use [16]. In our study, six subjects rated earplugs as
comfortable and 10 rated eye masks as comfortable, and
allsubjectsusedthemeasilyandkeptthemintactdur-
ing the study nights. However, previous studies showed
that some ICU patients were unwilling to use the ear-
plugs and/or eye masks because they found the inter-
ventions uncomfortable [28]. Some patients commented
that there was a feeling of heat, tightness, sore ears,
claustrophobia and still being a ble to hear when using
earplugs [15,29]. The reasons for this may include
improper inse rtion, individu al var iability in sensitivity or
anatomy of the ears, unsuitable type of earplugs and eye
masks and the a nxious state of patients. Future studies
should consider the sleep intervention according to
patients tolerability and explore other methods when
patients can not tolerate the devices. Light disturbances
may be blocked by other means and exclusion of blue
light at night by pat ients wearing g lasses that filter out
this light wavelength or nocturnal lighting sources with-
out blue light may be alternatives with regard to mini-
mizing adverse effects on the nocturnal melatonin surge.
In addition, critical care nurses should patiently provide
accurate instruction and assistance for use of earplugs
and eye masks, which may help mor e patients to benefit
from the use of the earplugs and eye masks to promote
better sleep [29].
Previous studies consistently found ICU patients suf-
fered from severe sleep disruption, with a n increased
percentage of wakefulness and stage 1 sleep and a
decrease or absence of both slow wave sleep and REM
sleep [1-3]. Our study indicates a significant difference
in PSG of percentage of REM sleep, REM latency and
arousal index b etween NL and NLEE. Although percen-
tage of REM sleep (12.9%) was statistically significantly
higher in the NLEE period, t he absolute figure in NL
(9.3%) period is still high compared with that frequently
reported in ICU patient PSG studies in which REM per-
centage is often less than 5% [1,2]. Our study cannot
completely simulate the ICU scenario; the healthy
volunteers slept relatively well in a sleep laboratory
while ICU patients are exposed to many other physical
and psychological stressors during their acute illness,
which may also contribute to their sleep disturbance.
Table 3 Subjective perception of sleep disruption (n = 14)
No disruption A little disruption but able to
fall asleep
Sometimes unable to
fall sleep
Light sleep, easy be
awakened
Significant disruption, awake
all night
Noise 0 11 2 1 0
Light 0 8 1 5 0
Table 4 Evaluation of earplugs and eye masks (n = 14)
Helpful to sleep promotion Comfortable Effective for noise/light reduction Easy to apply
Earplugs 6 6 10 11
Eye masks 8 10 13 14
Table 2 Subjective assessment of sleep quality and state anxiety by condition
Baseline night NL night NLEE night ANOVA P Contrast P
State anxiety 28.7 ± 6.3 32.5 ± 5.6 29.8 ± 6.4 0.06 0.28
Sleep quality 1.7 ± 1.3 4.1 ± 1.7 2.3 ± 1.3 0.00 0.001
ANOVA, repeated measures analysis of variance; Contrast, paired students test or wilcoxons rank sum test of simulated ICU environment with and without
earplugs and eye masks; NL, recorded ICU noise and light exposure; NLEE, recorded ICU noise and light, subjects wore earplugs and eye masks.
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Melatonin is the key circadian regulatory hormone in
humans. Cortisol is an important stress hormone. Mela-
tonin se cretion normally increases at night and decreases
in the early morning hours. In contrast, cortisol secretion
falls. Both are biological markers of the circadian rhythm.
Melatonin therapy has been shown to be ef fective in the
resetting of sleep-wake cycles, the entrainment of circa-
dian rhythms and the treatment of ch ronic insomnia
[30,31]. The melatonin secretion pattern has been related
to the sleep disturbances observed in the ICU [13,14].
Recently there has been some evidence that exogenous
melatonin is effective in improving s leep in ICU patients
[28,32]. Sleep intervention should be extended to a coor-
dinated exogenous melatonin therapy with bright light
[28]. Friese suggested that lighting could be coupled with
shielding o f patients eyes to allow for a sufficiently lit
environment so ICU staff could carry out necessary
nighttime activit ies and minimize retinal stimulation for
the patients [33]. Most previous studies evaluated the
effects of earplugs, and recently two studies indicated
that earplugs and eye ma sks w ere a relatively che ap wa y
to improve sleep quality in critically ill patients [15,34].
In fact, our study found that subjects disliked light as
much as noise and eye masks are better than ear plugs in
terms of the subjects tolerability.
In addi tion, our finding of significantly higher co rtisol
levels when exposure to ICU noise and light agreed with
previous results that acute noise stress invokes the stress
response and high levels of stress hormones [35].
Limitations of the study and suggestions for future
studies
Our study design has a number of limitations, which
should be reviewed. First, the study w as performed in a
sleep laboratory with healthy subjects rather than in an
ICU set ting of critically ill patients, and therefore could
not completely simulate the full auditory and visual
experience of the ICU. Second, the study was only per-
formed for a nine-hour nocturnal period rather than
over 24 hours. T he ICU pat ients experienc e circadian
rhythm disturbances with sleep traversing the day and
night. Therefore, an ideal study should measure the
sleep in healthy volunteers lying recumbent over a 24-
hour period to completely simulate the ICU scenario.
Our study combined noise and light as e nvironmental
stimuli and used earplugs and eye masks as intervention,
so we were unable to measure the effect of each one
separately on sleep and hormones secretion. Further stu-
dies are needed to elucidate the separate mechanisms of
ICU noise and light on sleep disturbance and hormones
secretion. In addition, our sample sizes were small,
which limited the power of our statistical analyses.
Future studies with larger and more diversity of the par-
ticipants would likely support these recommendations.
Conclusions
In summary, our results found that use of earplugs and
eye masks in subjects not only improves subjective sleep
quality, but also incr eases the amount of REM sleep and
nocturnal melatonin levels in a simulated ICU environ-
ment. Our pilot study provides a reasonable basis for
promoting the use of earplugs and eye masks for ICU
patients. Sleep is a b asic human need, sleep disruption
may contribute to patient morbidity and degenerate
quality of life [4,5]. Therefore, we recommend the rou-
tine use of earplugs and eye masks in all ICU patients
even though some patients may b e undergoing o ngoing
disease processes. Future studies should be designed to
determine if t he use of earplugs and eye masks will
improve the sleep quality and ultimately benefit the clin-
ical outcome of critically ill patients.
Key messages
Subjects had poorer perceived sleep quality, more
light sleep, longer REM latency, and less REM sleep
when exposed to simulated ICU noise and light.
Nocturnal melatonin and c ortisol secretion levels
differed significantly by experimental condition.
Use of earplugs and eye masks r esulted in more
REM time, shorter REM latency, less arousal and an ele-
vation of nocturnal melatonin levels.
Abbreviations
6-SMT: 6-sulphatoxymelatonin; ANOVA: analysis of variance; CCU: coronary
care unit; CHin EMG: sub-mental electromyogram; CSICU: cardiac surgical
ICU; EEG: electroencephalogram; ELISA: enzyme-linked immunosorbent assay;
MICU: medical ICU; NL: recorded ICU noise and light exposure; NLEE: NL plus
use of earplugs and eye masks; PSG: polysomnography; PSQI: Pittsburgh
Sleep Quality Index; RAI: radioimmunoassay; REM: rapid eye movement; SICU:
surgical ICU; STAI: Spielberger State-Trait Anxiety Inventory.
Acknowledgements
Thanks are due to Ms Wang Wanyu, Ms Lin yuanjian, Ms Zeng jing, Zhang
Yixiang MD, and Li Yueping MD for their support to the study. The authors
also thank the referees for their careful review of the manuscript.
Author details
1
School of Nursing, Fujian Medical University, Jiaotong Road 88, Fuzhou,
350004, PR China.
2
Sleep-Breath Disorders Center, Second Affiliated Hospital,
Zhongshan Road 34, Quanzhou, 362000, PR China.
3
Department of Nuclear
Medicine, Fujian Province Hospital, East Street 134, Fuzhou, 350001,
PR China.
Authors contributions
JX and ZY designed the study, and participated in the coordination and
writing of the manuscript. HR performed data collection, data entry,
statistical analysis and wrote the manuscript. CX participated in the data
collection, data entry, and statistical analysis. ZY was responsible for analysis
of the levels of 6-SMT and cortisol.
Competing interests
The authors declare that they have no competing interests.
Received: 2 October 2009 Revised: 23 December 2009
Accepted: 18 April 2010 Published: 18 April 2010
Hu et al. Critical Care 2010, 14:R66
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doi:10.1186/cc8965
Cite this article as: Hu et al.: Effects of earplugs and eye masks on
nocturnal sleep, melatonin and cortisol in a simulated intensive care
unit environment. Critical Care 2010 14:R66.
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... The use of earplugs causing an uncomfortable or very uncomfortable feeling may explain the discrepancy between the findings of the previous meta-analysis and the current network meta-analysis ( Huang et al., 2015 ). Not staying in place, sore ears, and anxiety when no background noise is heard are factors that may also contribute to an unwillingness to use earplugs (Hu et al., 2010, Hu et al., 2010Richardson et al., 2007, Scotto et al., 2009. The findings of the current study further support the argument that the use of earplugs alone could not significantly improve-and is even prone to impair-sleep quality in people who are critically ill, compared with usual care. ...
... The use of earplugs causing an uncomfortable or very uncomfortable feeling may explain the discrepancy between the findings of the previous meta-analysis and the current network meta-analysis ( Huang et al., 2015 ). Not staying in place, sore ears, and anxiety when no background noise is heard are factors that may also contribute to an unwillingness to use earplugs (Hu et al., 2010, Hu et al., 2010Richardson et al., 2007, Scotto et al., 2009. The findings of the current study further support the argument that the use of earplugs alone could not significantly improve-and is even prone to impair-sleep quality in people who are critically ill, compared with usual care. ...
... When people are admitted to critical care units, deprivation of natural light due to the lack of windows and stimulation due to 24-hour artificial light are the main factors contributing to sleep disturbance in critical care units. Accordingly, a dysregulated light-dark cycle prohibits nighttime melatonin secretion through the pineal gland, and wearing an eye mask during sleep may elevate melatonin levels, leading to improved sleep quality ( Hu et al., 2010 ). Therefore, critical care nurses should assess the acceptability of eye masks and earplugs and provide adequate assistance and instructions to aid people in selecting the best device for improving their sleep quality in critical care units. ...
Article
Background Disrupted sleep is a critical and highly prevalent concern among critically ill patients requiring intensive care. However, the question of which nonpharmacological intervention represents the best strategy for improving sleep quality remains unanswered. Objective To compare the efficacy of nonpharmacological interventions in improving sleep quality in people who are critically ill. Methods Databases, namely PubMed, Embase, CINAHL, and ProQuest Dissertations and Theses A&I, were searched from their inception up until January 15, 2021, for relevant randomised controlled trials. No language or time period restrictions were applied. Only randomised controlled trials examining the effects of nonpharmacological interventions on sleep among adults (aged ≥18 years) admitted to an intensive care unit were included. A random-effects model was used for data analyses. The study protocol was registered at PROSPERO (CRD42021232004). Results Twenty randomised controlled trials involving 1,207 participants were included. Music combined with earplugs and eye masks (standardised mean difference =1.64), eye masks alone (0.98), aromatherapy (0.87), and earplugs combined with eye masks (0.61) significantly improved sleep quality compared with routine care (all p <0.05). Music combined with earplugs and eye masks significantly enhanced sleep quality in comparison with music (1.34), earplugs combined with eye masks (1.03), and nursing intervention (1.76, all p <0.05). Earplugs alone was less likely to have effects on sleep quality improvement compared with routine care. Conclusion Eye masks alone and music combined with earplugs and eye masks appear to be the most effective interventions for improving sleep quality in people who are critically ill. Critical care nurses should incorporate the use of eye masks alone or music combined with eye masks into sleep care.
... No interventions took place in our study to better aid sleep in our patients, but several studies have looked at interventions and mechanisms to promote sleep, with some demonstrating improvements in the quality of sleep [30,32,[35][36][37][38]. The most common include the use of earplugs and eye masks, strategies for noise and light level reductions or the use of relaxing music [32,[37][38][39][40]. Non-pharmacological interventions carried out by nurses could also prove useful in helping aid sleep, such as modifying the time of certain patient-care related activities [39]. ...
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Sleep is disturbed in critically ill patients and is a frequently overlooked complication. The aim of our study is to evaluate the impact of sound levels in our surgical ICU on our patients’ sleep on the first night of admission. The study was performed in a tertiary care university hospital, in a 12-bed surgical ICU. Over a 6-week period, a total of 148 adult, non-intubated and non-sedated patients completed the study. During this six-week period, sound levels were continuously measured using a type II sound level meter. Sleep quality was evaluated using the Richards–Campbell Sleep Questionnaire (RCSQ), which was completed both by patients and nurses on the first morning after admission. A non-significant correlation was found between night sound levels and sleep quality in the overall sample (r = −1.83, 95% CI; −4.54 to 0.88, p = 0.19). After multivariable analysis, a correlation was found between higher sound levels at night and lower RCSQ evaluations (r = −3.92, 95% CI; −7.57 to −0.27, p = 0.04). We found a significant correlation between lower sound levels at night and a better quality of sleep in our patients; for each 1 dBA increase in LAFeq sound levels at night, patients scored 3.92 points lower on the sleep questionnaire.
... One of the ways to control light and noise is through earplugs and eye masks, which are noninvasive and cost-effective and considered convenient to use. Studies showed that the usage of tools such as earplugs and eye masks positively affect sleep, is low-cost, useful, and that qualified and longer sleep time is obtained [9][10][11]. We reviewed the published literature systematically on the impact of using earplugs and eye masks on patient sleep quality in ICUs. ...
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b> Introduction: Patients in the intensive care unit (ICU) have severe and complex disease characteristics and their sleep problems should not be ignored. Poor-quality sleep is associated with impaired immune function and associated susceptibility to disease and infection, decreased energy levels, delirium, delays in recovery. This study is conducted to examine the results of studies examining sleep quality using earplugs and eye masks in the ICU. Methods: PubMed, Science Direct, Google Scholar, and Medline databases were scanned using “Earplugs, Eye masks, Sleep quality, Intensive care units” as keywords. For the search strategy, a query in a patient-intervention-compare-result (PICO) format was used. P: Patients in intensive care; I: Earplugs and eye mask; C: Noise, Light, and Sleep Quality; O: Using earplugs and eye masks improves sleep quality. Results: We included the 17 most eligible studies meeting defined inclusion/exclusion criteria involving 1,372 participants. Randomized controlled trial was used mostly as study design. The interventions within the scope of the studies were earplugs, eye masks, relaxing music, and quiet time protocol. Richard Campbell Sleep Questionnaire and Verran and Snydern Halpern Sleep Scale were the most used scale. Most of the studies reviewed found that the use of non-pharmacological interventions showed a significant improvement in sleep quality. Earplugs and eye masks were found to have potential positive effects on sleep quality and delirium incidence in ICU patients. Conclusion: The use of earplugs and eye masks is a noninvasive, economical, and effective way to improve sleep quality in adult ICU patients.
... [23,24] Because the ICU environment is mainly based on continuous observation and monitoring of the patient and has a unique complexity to achieve this goal, these conditions mainly interfere with patients' sleep and lead to their inactivity. [25][26][27] Unfamiliar devices and painful procedures have also led to the discomfort of the study participants, which is consistent with many studies. Pain is a common and distressing symptom experienced by intensive care patients at a rate of 40%-77%. ...
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Introduction: Discomfort in patients admitted to the ICU occurs due to various reasons and leads to a stressful situation in these patients. Discomfort significantly affects the ability to cope psychologically, the process, and results of treatment. The aim of this study was to investigate the experiences of discomfort and its self-management strategies in patients admitted to the ICU. Methods: This qualitative study was conducted in the period of September 2019 to December 2020 through in-depth interviews with 13 patients admitted to the ICU who were selected by purposive sampling. Interviews continued until data saturation. All interviews were recorded, transcribed, and analyzed using MAXQDA18 software by the conventional Lundman and Graneheim content analysis method. Results: The two main themes including "hospitalization with anxiety" and "coping with the horror of ICU" emerged from the uncomfortable experiences of patients admitted to the intensive care unit. "Hospitalization with anxiety" included five subthemes: "fear of disability and possible death," "separation from family," "understanding ambiguity and contradiction in treatment," "environmental disruptors," and "painful and unfamiliar devices and treatments." "Coping with the horror of ICU" included three subthemes: "recourse to spirituality," "benefiting from psychosocial coping," and "information search."
... Alternatively, patients in ICUs can be protected from the negative effects of environmental sound and light individually by the use of earplugs and eye masks. An analysis of the literature revealed that many studies have investigated the effects of earplugs and eye masks upon sleep quality, 2,9,17,[21][22][23][24][25][26][27] but the number of the studies simultaneously investigating their effects upon sleep and delirium is remarkably small 11,28,29 This being the case, the present study aims to investigate the effect of earplugs and eye masks used during the night upon sleep quality and the development of delirium in patients treated in ICUs. ...
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Background: Environmental factors such as loud sounds and bright lights in intensive care units can cause sleep disorders and delirium. Aim: The present study aims to investigate the effects of the overnight use of earplugs and eye masks by intensive care patients on their sleep quality and the degree of delirium. Study design: This randomized controlled experimental study was conducted on the patients admitted to a coronary intensive care unit. Methods: The patients in the experimental group used earplugs and eye masks during the night, while those in the control group received only routine care. Data were collected using an information form, the Richards-Campbell sleep questionnaire (RCSQ), and the intensive care delirium screening checklist (ICDSC). Results: The study included a total of 84 patients, 42 in the experimental group and 42 in the control group. The baseline average score of the patients in the experiment group on the RCSQ was 40.11 ± 16.55, with a Time 1 average score of 64.09 ± 14.07 and a Time 2 average score of 72.07 ± 11.75; their baseline average score on the ICDSC was 0.47 ± 0.50, with a Time 1 average score of 0.33 ± 065 and a Time 2 average score of 0.19 ± 039. The baseline average score of the patients in the control group on the RCSQ was 44.07 ± 7.30, with a Time 1 average score of 46.97 ± 9.22 and a Time 2 average score of 47.04 ± 11.53; the baseline average score of the control group on the ICDSC was 0.42 ± 0.50, with a Time 1 average score of 0.50 ± 0.70 and a Time 2 average score of 0.57 ± 0.66. A statistically significant difference was found between the Time 1 and Time 2 average scores of the experimental and control groups on the RCSQ and between the Time 2 average scores of the experimental and control groups on the ICDSC (U = 198.00, P < .001; U = 70.000, P < .001; U = 614.000, P = ·004 respectively). Conclusions: The earplugs and eye masks used by the intensive care patients overnight were associated with an increase in sleep quality and a decrease in the degree of delirium. Relevance to clinical practice: The use of earplugs and eye masks is recommended for intensive care units in supporting sleep quality and preventing delirium.
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Insufficient sleep and sleep disorders are highly prevalent in the population and are associated with significant morbidity and mortality. Adverse outcomes of insufficient sleep and/or sleep disorders are weight gain and obesity, cardiovascular disease, diabetes, accidents and injuries, stress, pain, neurocognitive dysfunction, psychiatric symptoms, and mortality. Exposure to sleep difficulties varies by age, sex, race/ethnicity, and socioeconomic status; significant sleep health disparities exist in the population. Societal influences, such as globalization, technology, and public policy, affect sleep at a population level.
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Many studies have shown that hospital staff and patients are subject to noise levels in excess of those specified in the World Health Organization (WHO) guidelines. This article presents the results of a single-centre study of noise in four wards in an acute hospital in Adelaide, Australia. The study measured noise in multi-bed bays, as well as nurse stations, and involved continuous noise monitoring between one and three days. For 4-bed and 6-bed patient bays, as well as nurse stations, the maximum, minimum and average equivalent 1-minute A-weighted sound levels were relatively constant from 22:00 until 06:00, increase from 06:00 until 09:00, remain raised until 18:00, and then decrease from 18:00 until 22:00. Measured average equivalent A-weighted noise levels for nurse stations and patient rooms were 56.6 dB(A) and 54.8 dB(A) respectively. Noise levels were higher in the 6-bed bays compared to the 4-bed bays with average equivalent A-weighted noise levels of 55.7 and 54.3 dB(A) respectively. The results were consistent with similar hospital studies, with noise levels exceeding WHO guidelines for patient comfort.
Chapter
Numerous aspects of the sleep and circadian environment affect sleep duration and quality. The article focuses on creating an optimal overall sleep environment. This first entails evaluating the major components of the sleep environment: the bedroom environment itself, the body environment, the mental environment, as well as daily and nightly routines. Key factors to assess within each of these environmental components are identified. These are followed by suggestions for changes to the environmental factors that may more readily facilitate consistently good sleep.
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Background There is a growing body of research that identifies sound levels in an intensive care unit to be higher than current recommendations; although the quality and reproducibility of these studies has been questioned. Noise is generated by the multiplicity of supportive equipment necessary for patient management and by the staff who provide or enable care. Patients remember noise as a prominent and sometimes distressing feature of their intensive care admission. There is currently no study that provides a robust description of the sources of noise in an intensive care unit. Therefore, the aim of this study was to identify the sources of sound and their relative contribution to the sound environment of an intensive care unit. Methods Fifty hours of observational data were collected over a month, using a datasheet designed and piloted for this purpose. Data was collected at four bed spaces, providing equal representation across each bed space, hour of the day and day of the week. A priori, five categories of sound were identified, communication, clinical tasks, housekeeping tasks, alarms and miscellaneous; 55 individual sources of sound were reported under these categories. Concurrently, continuous sound pressure levels were monitored at each bed space. Results 16,784 episodes of sound were identified during the 50hrs of data collection; the greatest number of episodes were reported in the communication category n = 5699 (34%), with clinical tasks n = 3282 (20%), housekeeping tasks n = 3247 (19%), alarms n = 2939 (18%) and miscellaneous n = 1617 (10%). The highest number of episodes for an individual sound source was nurse/nurse communication n = 1595 (10%), followed by bin lids n = 1004 (6%) and oxygen/nebulisers n = 945 (6%). Of the 55 sources recorded, the top 25 accounted for 86% of the episodes. The average SPL (LAeq50hrs) across all bed-spaces during this study was 65.1 dB (SD 3.98) with little variation between day (66.3 dB; SD 3.37) and night time (62.7 dB; SD 3.81), The four bed spaces demonstrated difference in average LAeq, with the nosiest being the single room (LAeq12hrs69.1 dB, SD 1.98); and the quietest bed space 5 in an open bay (LAeq13hrs59.8 dB, SD 2.49). Conclusion Concurrent observational and quantitative data collection enabled detailed analysis of the sound environment. The results provide greater clarity than previous study, into the individual sound sources and their relative contribution to the noise environment of an intensive care unit. This information will help identify which sources of sound are most amenable to modification. There is a need for further study to understand the perception of noise in an intensive care unit, by its main users; the patients, staff and visitors. Current SPL guidance appears unachievable without a change in ambient sound levels.
Article
Background Critically ill patients suffer from sleep pattern disturbances in intensive care units, negatively affecting their recovery. With this, nurses are faced with a great challenge to deal with these disturbances in critically ill patients. Aim This study aimed to explore the effectiveness of alternative methods to nursing strategies for promoting night sleep pattern among coronary intensive care patients. Methods The study was conducted at the coronary intensive care unit (CCU) of the Aswan University Hospital (Aswan– Egypt). Pertinent data were collected utilizing two tools. The first tool was the quality of sleep sheet, which included two parts: personal bio demographic data and a Richards–Campbell sleep questionnaire for monitoring the sleep qualities of ICU patients. The second tool was the stress factors in the ICU questionnaire used to measure stress perception. A quantitative survey was carried out to meet the aim of this study, and the purposive sample included 85 conscious CCU patients. Results Implementation of the alternative methods to nursing strategies revealed highly significant impacts regarding the domains in stress factor perception (p <0.000) and items of sleep quality in the ICU. Significant differences were found in the means of sleep depth, latency, returning to sleep, sleep quality, and noise in the ICU (p <0.005). Conclusion Alternative nursing strategies improved the sleep quality of ICU patients using the following alternative methods performed by nurses, which included aromatherapy, body massage, listening to calm music, and decrease of stress factors in the ICU. Therefore, it is recommended to use these alternative nursing strategies in intensive care units to improve the patients' night sleep pattern.
Article
BACKGROUND: Sleep deprivation may contribute to impaired immune function, ventilatory compromise, disrupted thermoregulation, and delirium. Noise levels in intensive care units may be related to disturbed sleep patterns, but noise reduction has not been tested in this setting. OBJECTIVE: To measure the effect of a noise reduction intervention on the sleep of healthy subjects exposed to simulated intensive care unit noise. METHODS: After digital audiotape recording of noise and development of the noise reduction intervention, 5 nocturnal 8-hour periods of sleep were measured in 6 paid, healthy volunteers at 7-day intervals in a sleep disorders center. Polysomnographic data were collected by experienced sleep disorders technicians and scored by certified raters. After the first 3 quiet nights, earplugs were randomly assigned to be worn on the fourth and fifth nights during exposure to the recorded noise. Sound pressure levels were measured during all 5 nights. RESULTS: Sleep architecture and sound measurements on quiet nights did not differ significantly. Sound levels were significantly lower on quiet nights than on noise nights. Exposure to the noise increased the number of awakenings, percentage of stage 2 sleep, and rapid eye movement latency and decreased time asleep, sleep maintenance efficiency index, and percentage of rapid eye movement sleep. Earplugs worn during exposure to the noise produced a significant decrease in rapid eye movement latency and an increase in the percentage of rapid eye movement sleep. CONCLUSION: The results provide a reasonable basis for testing the effects of earplugs on the sleep of critically ill subjects.
Article
Sleep deprivation and fragmentation occurring in the hospital setting may have a negative impact on the respiratory system by decreasing respiratory muscle function and ventilatory response to CO2. Sleep deprivation in a patient with respiratory failure may, therefore, impair recovery and weaning from mechanical ventilation. We postulate that light, sound, and interruption levels in a weaning unit are major factors resulting in sleep disorders and possibly circadian rhythm disruption. As an initial test of this hypothesis, we sampled interruption levels and continuously monitored light and sound levels for a minimum of seven consecutive days in a medical ICU, a multiple bed respiratory care unit (RCU) room, a single-bed RCU room, and a private room. Light levels in all areas maintained a day-night rhythm, with peak levels dependent on window orientation and shading. Peak sound levels were extremely high in all areas representing values significantly higher than those recommended by the Environmental Protection Agency as acceptable for a hospital environment. The number of sound peaks greater than 80 decibels, which may result in sleep arousals, was especially high in the intensive and respiratory care areas, but did show a day-night rhythm in all settings. Patient interruptions tended to be erratic, leaving little time for condensed sleep. We conclude that the potential for environmentally induced sleep disruption is high in all areas, but especially high in the intensive and respiratory care areas where the negative consequences may be the most severe.
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This study aimed to determine the effects of earplug use on the subjective experience of sleep for patients in critical care. The negative effects of noise in critical care include sleep disturbances, increased stress response, and reduced patient satisfaction. The nature of critical care often precludes quiet time protocols. Previous studies indicated that earplugs can improve REM sleep and sleep efficiency. This study examined the effects of earplugs as a non-invasive method for improving the subjective sleep experience and increasing patient satisfaction. Quasi-experimental intervention study with random assignment of subjects. Subjects were non-ventilated, non-sedated adults admitted to critical care. The intervention group used earplugs during nighttime sleep hours allowing short term removal during patient care. Participants completed the Verran-Snyder-Halpern Sleep Scale, an 8-question visual analogue scale, to describe their subjective response to sleep. Two sample T-tests were used to detect differences between the group scores. 88 participants (49 intervention/39 control) completed the study. Mean age 63, 56% males, 93% Caucasian. Total sleep satisfaction scores were significantly better for the intervention group (p = .002). Seven of the subjective categories were independently significant (p = .005-.044). One category, satisfaction with the amount of time needed to fall asleep, was not significant (p = .111). Earplug use improved the subjective experience of sleep for un-medicated critical care patients without interfering with care delivery. The negligible cost and low level of invasiveness of earplugs makes this preferable as a primary intervention to promote sleep while avoiding unnecessary sedating medications.