ArticlePDF Available

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

  • The Second Affiliated Hospital of Fujian Medical University

Abstract and Figures

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.
Content may be subject to copyright.
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
, Xiao-ying Jiang
, Yi-ming Zeng
, Xiao-yang Chen
, You-hua Zhang
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.
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.
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:
School of Nursing, Fujian Medical University, Jiaotong Road 88, Fuzhou,
350004, PR China
Hu et al. Critical Care 2010, 14:R66
© 2010 Hu et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons
Attribution License ( censes/by/2.0), which permits unrestricted use, distribution, and reproduction in
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
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),
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
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.
Hu et al. Critical Care 2010, 14:R66
Page 2 of 9
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.
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,
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
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.
Hu et al. Critical Care 2010, 14:R66
Page 3 of 9
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.
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
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.
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
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
Hu et al. Critical Care 2010, 14:R66
Page 4 of 9
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
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
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.
Hu et al. Critical Care 2010, 14:R66
Page 5 of 9
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.
Hu et al. Critical Care 2010, 14:R66
Page 6 of 9
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
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
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.
Hu et al. Critical Care 2010, 14:R66
Page 7 of 9
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
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.
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.
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.
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
School of Nursing, Fujian Medical University, Jiaotong Road 88, Fuzhou,
350004, PR China.
Sleep-Breath Disorders Center, Second Affiliated Hospital,
Zhongshan Road 34, Quanzhou, 362000, PR China.
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
Page 8 of 9
1. Freedman NS, Gazendam J, Levan L, Pack AI, Schwab RJ: Abnormal sleep/
wake cycles and the effect of environmental noise on sleep disruption
in the intensive care unit. Am J Respir Crit Care Med 2001, 163:451-457.
2. Cooper AB, Thornley KS, Young GB, Slutsky AS, Stewart TE, Hanly PJ: Sleep
in critically ill patients requiring mechanical ventilation. Chest 2000,
3. Friese RS, Diaz-Arrastia R, McBride D, Frankel H, Gentilello LM: Quantity and
quality of sleep in the surgical intensive care unit: are our patients
sleeping? J Trauma 2007, 63:1210-1214.
4. Orwelius L, Nordlund A, Nordlund P, Edéll-Gustafsson U, Sjöberg F:
Prevalence of sleep disturbances and long-term reduced health-related
quality of life after critical care: a prospective multicenter cohort study.
Crit Care 2008, 12(4):R97.
5. Mejer TJ, Eveloff SE, Bauer MS, Schwartz WA, Hill NS, Millman RP: Adverse
environmental conditions in the respiratory and medical ICU settings.
Chest 1994, 105:1211-1216.
6. Drouot X, Cabello B, dOrtho M, Brochard L: Sleep in the intensive care
unit. Sleep Med Rev 2008, 12:391-403.
7. Aaron JN, Carlisle CC, Carskadon MA, Meyer TJ, Hill NS, Millman RP:
Environmental noise as a cause of sleep disruption in an intermediate
respiratory care unit. Sleep 1996, 19:707-710.
8. Freedman NS, Kotzer N, Schwab RJ: Patient perception of sleep quality
and etiology of sleep disruption in the intensive care unit. Am J Respir
Crit Care Med 1999, 159:1155-1162.
9. Leur Van de JP, Schans van der CP, Loef BG, Deelman BG, Geertzen JH,
Zwaveling JH: Discomfort and factual recollection in intensive care unit
patients. Crit Care 2004, 8(6):R467-73.
10. Gabor J, Cooper A, Crombach S, Lee B, Kadikar N, Bettger HE, Hanly PJ:
Contribution of the intensive care unit environment to sleep disruption
in mechanically ventilated patients and healthy subjects. Am J Respir Crit
Care Med 2003, 167:708-715.
11. Walder B, Francioli D, Meyer JJ, Lançon M, Romand JA: Effects of
guidelines implementation in a surgical intensive care unit to control
nighttime light and noise levels. Crit Care Med 2000, 28:2242-2247.
12. Boivin DB, Duffy JF, Kronauer RE, Czeisler CA: Dose-response relationships
for resetting of human circadian clock by light. Nature 1996, 379:540-542.
13. Shilo L, Dagan Y, Smorjk Y, Weinberg U, Dolev S, Komptel B, Balaum H,
Shenkman L: Patients in the intensive care unit suffer from severe lack of
sleep associated with loss of normal melatonin secretion pattern. Am J
Med Sci 1999, 317:278-281.
14. Olofsson K, Alling C, Lundberg D, Malmros C: Abolished circadian rhythm
of melatonin secretion in sedated and artificially ventilated intensive
care patients. Acta Anaesthesiol Scand 2004,
15. Richardson A, Allsop M, Coghill E, Turnock C: Earplugs and eye masks: do
they improve critical care patients sleep? Nurs Crit Care 2007, 12:278-286.
16. Wallace CJ, Robins J, Alvord LS, Walker JM: The effects of earplugs on
sleep measures during exposure to simulated intensive care unit noise.
Am J Crit Care 1999, 8:210-219.
17. Xie H, Kang J, Mills GH: Clinical review: The impact of noise on patients
sleep and the effectiveness of noise reduction strategies in intensive
care units. Crit Care 2009, 13(3):208.
18. Shek DT: The Chinese version of the State-Trait Anxiety Inventory: its
relationship to different measures of psychological well-being. J Clin
Psychol 1993, 49:349-358.
19. Chinese Association of Critical Care Medicine: Guidelines of intensive care
unit (ICU) construction and management in China. Chin Crit Care Med
2006, 18(7):387-388.
20. Rechtschaffen A, Kales A: A manual of standardized terminology,
techniques and scoring system for sleep stages of human subjects. NIH
Publication 204 Los Angeles: Brain Information Service/Brain Research
Institute, UCLA 1968, 57.
21. American Sleep Disorders Association: EEG arousals: scoring rules and
examples. Sleep 1992, 15:173-184.
22. Richardson SJ: A comparison of tools for the assessment of sleep pattern
disturbance in critically ill adults. Dimens Crit Care Nurs 1997, 16:226-239.
23. Spielberger CD: Manual for the State-Trait Anxiety Inventory (STAI) PaloAlto:
Consulting Psychologists Press 1983.
24. Williams R, Karacan L, Hurst C: EEG of human sleep: Clinical applications.
New York: John Wiley & Sons 1974.
25. Topf M, Davis JE: Critical care unit noise and rapid eye movement (REM)
sleep. Heart Lung 1993, 22:252-258.
26. Ugras GA, Öztekin SD: Patient perception of environmental and nursing
factors contributing to sleep disturbances in a neurosurgical intensive
care unit. Tohoku J Exp Med 2007, 212:299-308.
27. Cabello B, Thille AW, Drouot X, Galia F, Mancebo J, dOrtho MP, Brochard L:
Sleep quality in mechanically ventilated patients: comparison of three
ventilatory modes. Crit Care Med 2008, 36:1749-1755.
28. Bourne RS, Mills GH, Minelli C: Melatonin therapy to improve nocturnal
sleep in critically ill patients: encouraging results from a small
randomised controlled trial. Crit Care 2008, 12:R52.
29. Scotto C, McClusky C, Spillan S, Kimmel J: Earplugs improve patients
subjective experience of sleep in critical care. Nurs Crit Care 2009,
30. Dahlitz M, Alvarez B, Vignau J, English J, Arendt J, Parkes JD: Delayed sleep
phase syndrome response to melatonin. Lancet 1991, 337:1121-1124.
31. Sack RL, Brandes RW, Kendall AR, Lewy AJ: Entrainment of free-running
circadian rhythms by melatonin in blind people. N Engl J Med 2000,
32. Ibrahim MG, Bellomo R, HartA GK, Norman TR, Goldsmith D, Bates S, Egi M:
A double-blind placebo-controlled randomised pilot study of nocturnal
melatonin in tracheostomised patients. Crit Care Resusc 2006, 8:187-191.
33. Friese RS: Sleep and recovery from critical illness and injury: A review of
theory, current practice, and future directions. Crit Care Med 2008,
34. Koo YJ, Koh HJ: Effects of eye protective device and ear protective
device application on sleep disorder with coronary disease patients in
CCU. Taehon Kanho Hakhoe Chi 2008, 38(4):582-592.
35. Leproult R, Colecchia EF, Lhermite-Baleriaux M, Van Cauter E: Transition
from dim to bright light in the morning induces an immediate elevation
of cortisol Levels. J Clin Endocrinol Metab 2001, 86:151-157.
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.
Submit your next manuscript to BioMed Central
and take full advantage of:
Convenient online submission
Thorough peer review
No space constraints or color figure charges
Immediate publication on acceptance
Inclusion in PubMed, CAS, Scopus and Google Scholar
Research which is freely available for redistribution
Submit your manuscript at
Hu et al. Critical Care 2010, 14:R66
Page 9 of 9
... Intravenous sedatives can cause respiratory depression and hypotension during surgery, necessitating close monitoring and prompt treatment of patients to avoid medical emergencies [6][7][8]. Thus, non-pharmacological interventions that could help reduce the dose of sedatives as well as the patient's anxiety are important clinically. 2 of 9 Environmental factors should be considered when maintaining appropriate sedation during surgery [9][10][11]. Bright lighting and surgical noise in the operating room can disturb the patient's ability to relax and interfere with proper sedation. ...
... Bright lighting and surgical noise in the operating room can disturb the patient's ability to relax and interfere with proper sedation. According to previous studies, earplugs and eye masks, which were employed to reduce external noise and light stimulation, improved the patient's quality of sleep and decreased the incidence of postoperative disorientation [9,12]. Studies have reported that playing music to patients through headphones could reduce anxiety and sedative requirements during spinal anesthesia [1,13]. ...
... Research on the effects of earplugs and eye masks during sleep has shown that they significantly improve sleep quality [9,12]. However, controlled clinical data on the effects of active blockade of external stimuli on sedation quality are insufficient. ...
Full-text available
Intravenous sedative drugs are commonly administered during regional anesthesia. However, reducing the excessive use of sedatives while providing adequate sedation is important from the clinical perspective, since the use of sedatives can cause considerable complications. We hypothesized that the application of earmuffs and eye masks would help reduce the sedative dose required to maintain proper sedation by blocking external stimuli. Patients who underwent orthopedic surgery under spinal anesthesia were randomly allocated to the control (no intervention) or intervention group (wearing earmuffs and eye masks). Intravenous sedation was administered using target-controlled infusion of propofol. The target concentration was controlled to maintain a Modified Observer’s Assessment of Alertness and Sedation score of 3 or 4. The primary outcome was the intraoperative propofol requirement. We also investigated the incidence of apnea, and patient satisfaction. Propofol requirement was significantly lower in the intervention group than that in the control group (2.3 (2.0–2.7) vs. 3.1 (2.7–3.4) mg·kg−1·h−1; p < 0.001). Intraoperative apnea occurred less frequently (p = 0.038) and patient satisfaction was higher (p = 0.002) in the intervention group compared to the control group. This study demonstrated that the use of earmuffs and eye masks during sedation was associated with lower propofol requirement and improved sedation quality.
... Noise and light, including those from the natural environment, are the two main causes of sleep disturbances even when not they are consciously observed, leading to sleep fragmentation and overall poor sleep quality [10]. Sensory deprivation with eye mask and earplugs (EMEP) increase sleep duration by 40%-60% and improve sleep quality and sleep architecture among patients in intensive care unit [11][12][13][14]. When used during the first night after surgery in a post-anesthesia care unit, EMEP also improved sleep quality, reduced the number of awakenings, and significantly decreased self-administered opioid use [13]. ...
... However, sensitivity analysis showed a significantly higher proportion of participants in the EMEP increased their night sleep duration by at least 30 minutes from baseline, agree that they slept better, and expressed higher satisfaction with allocated sleep aid when compared to the HB arm, thus suggesting an advantage for EMEP over sham HB on these metrics. Our positive findings with EMEP use in a home environment corroborated that of Hu et al. [14] who found the use of EMEP increased the duration of rapid eye movement sleep and subjective sleep quality in a simulated intensive care unit environment. ...
... In our EMEP arm, the mean night sleep duration during the baseline week was 279 minutes with an increase of 25 minutes (9%). This increment is substantially less than the 40 to 60% [11,14] increment reported in the busy environment of the intensive care unit and the post-anesthesia unit [13], demonstrating the diminished but still efficacious sensory blockade of EMEP to improve sleep in the ambiance of the home bedroom. ...
Full-text available
Background Women experience significant sleep disruption throughout pregnancy. Lack of sleep during the last month of pregnancy is associated with longer labor, a higher rate of Cesarean births, gestational diabetes, hypertension, and preterm birth. Eye-mask and earplugs through sensory deprivation increase sleep duration and quality in patients in the intensive care environment but their impact at home or during pregnancy is not known. We sought to evaluate eye-mask and earplugs compared to sham/placebo headbands on night sleep duration in pregnancy. Materials and methods A randomized trial was performed in a university hospital in Malaysia. Nulliparas between 34 and 36 weeks of gestation with self-reported night sleep of fewer than six hours were randomized to the use of eye-mask and earplugs or “sham” headbands during night sleep (both introduced as sleep aids). Night sleep duration was measured through a wrist actigraphy monitor during non-intervention week one and intervention week two with the allocated sleep aid. Results Data from 56 participants were analyzed on an intention-to-treat basis. Mean night sleep duration increased in intervention week two compared to non-intervention week one in both trial arms, which were 279 ± 19 vs. 304 ± 19 minutes (mean increase of 25 minutes) p = <0.001 and 286 ± 21 vs. 302 ± 22 minutes (mean increase of 16 minutes) p = <0.001 for eye-masks-earplugs and headband respectively. However, the mean increase in night sleep duration across trial arms (p=0.13) was not significant. A higher proportion of participants in the eye-masks and earplugs arm had their night sleep duration increased by at least 30 minutes, 13/29 (45%) vs. 5/26 (19%), relative risk (RR) 2.3 (95% CI 1.0-5.6) p = 0.04, more likely to agree that they slept better 19/29 (66%) vs. 7/27 (26%), RR 2.2 (95% CI 1.1-4.6) p = 0.03, expressed higher satisfaction score with their sleep aid 7 (7.0-7.5) vs. 6 (5-7), p = 0.003 and had lower induction of labor rates 4/29 (14%) vs. 12/27 (44%), RR 0.3 (95%CI 0.1-0.8) p = 0.02. Conclusion Eye masks and earplugs use in nulliparas with short night sleep duration in late pregnancy, lengthen their night sleep duration over baseline. Sleep is reportedly better and maternal satisfaction is higher with eye masks and earplugs use.
... Inclusion criteria were women presenting for imminent delivery (in spontaneous labor, scheduled induction of labor or planned cesarean) at our labor or antenatal wards who were aged ≥ 18 years, with a singleton pregnancy and at term gestation (≥ 37 weeks confirmed by ultrasound before 22 weeks gestation). We excluded women with severe-moderate to severe anemia in pregnancy (hemoglobin level < 8 g/dl) [9,10], known major hemoglobinopathy [11,12], known gross fetal anomaly (as these characteristics might have major impact on HbA1c assessment or birth weight) and inability to consent due to language difficulty. ...
... Table 3 shows the analysis on the crude effect of independent covariables on LGA. On crude analysis, LGA was significantly associated with BMI, predelivery anemia (hemoglobin < 11 g/dl) [9] and Group B streptococcus carriage. On adjusted analysis controlling for these confounders, LGA was not significantly associated with raised HbA1c, AOR 1.43 95% CI 0.93-2.18 ...
Full-text available
Background There are no obvious thresholds at which the risk of adverse pregnancy outcomes increases as a result of maternal hyperglycemia. HbA1c level which is representative of average blood glucose levels over the last 2–3 months is not as strongly predictive of adverse outcome compared to blood glucose values of oral glucose tolerance test. Data is sparse on the predictive value of HbA1c at term just prior to delivery on adverse outcome. We sought to evaluate HbA1c taken on admission for delivery at term on adverse outcomes of Cesarean delivery and large (≥ 90 th centile) for gestational age (LGA) infants. Methods A prospective cross-sectional study was conducted in a university hospital in Malaysia from December 2017-August 2018. 1000 women at term whose deliveries were imminent were enrolled. Blood were drawn and immediately sent for HbA1c analysis at our hospital laboratory. Primary outcomes were Cesarean delivery and LGA. Results On crude analyses, Cesarean births (vs. vaginal births) were associated with significantly higher HbA1c (%) levels 5.4[5.2–5.7] vs. 5.3[5.1–5.6] P = < 0.001 but not for LGA vs. non-LGA 5.4[5.1–5.6] vs. 5.3[5.1–5.6] P = 0.17. After controlling for significant confounders identified on crude analysis (diabetes in pregnancy, parity, ethnicity, body mass index (BMI), previous cesarean, labor induction, Group B streptococcus (GBS) carriage and birth weight), HbA1c is independently predictive of Cesarean birth, adjusted odds ratio (AOR) 1.47 95% CI 1.06–2.06 P = 0.023 per HbA1c 1% increase. Following adjustment for significant confounders (BMI, predelivery anemia [hemoglobin < 11 g/dl] and GBS carriage), the impact of raised HbA1c level on LGA is AOR 1.43 95% CI 0.93–2.18 P = 0.101 per HbA1c 1% increase and non-significant. Conclusion Raised HbA1c level at term births in the general pregnant population is independently predictive of Cesarean delivery after adjustment for potential confounders including diabetes in pregnancy.
... However, the limited sample size could affect the rationality of the study conclusion. Hu et al. [27] tested urine aMT6s, the metabolite of melatonin, as a surrogate for serum melatonin in a simulated ICU environment and showed that the difference in nocturnal urine melatonin level of aMT6s was significant. Nevertheless, the results of a recent study confirmed that urinary melatonin secretion aMT6s is not a reliable measure of the melatonin level in critically ill patients [28]. ...
Full-text available
Abstract Background Patients treated in the intensive care unit (ICU) may experience a reversal of day and night. The circadian rhythm in ICU patients can be disturbed. Methods To explore the relationship between ICU delirium and the circadian rhythms of melatonin, cortisol and sleep. A prospective cohort study was carried out in a surgical ICU of a tertiary teaching hospital. Patients who were conscious during the ICU stay after surgery and were scheduled to stay in the ICU for more than 24 h were enrolled. Serum melatonin and plasma cortisol levels were measured three times a day by drawing arterial blood on the first three days after ICU admission. Daily sleep quality was assessed by the Richard-Campbell Sleep Questionnaire (RCSQ). The Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) was performed twice a day to screen for ICU delirium. Results A total of 76 patients were included in this study, and 17 patients developed delirium during their ICU stay. Melatonin levels were different at 8:00 (p = 0.048) on day 1, at 3:00 (p = 0.002) and at 8:00 (p = 0.009) on day 2, and at all three time points on day 3 (p = 0.032, 0.014, 0.047) between delirium and non-delirium patients. The plasma cortisol level in the delirium patients was significantly lower than that in the non-delirium patients at 16:00 on day 1 (p = 0.025). The changes in melatonin and cortisol secretion levels exhibited obvious biological rhythmicity in non-delirium patients (p
... Descriptive studies have defined and expanded our understanding of the relationship between environmental problems and serious sleep disturbances in the ICU [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. Consequently, several studies have evaluated interventions targeting sleep optimization in the ICU, including non-pharmacologic and pharmacologic interventions [21,30,[40][41][42][43][44][45][46][47][48][49][50][51]. As for pharmacological therapy, this should be for short periods, with continuous re-evaluation of the need due to adverse effects. ...
Full-text available
Introduction: In critically ill patients, sleep and circadian rhythms are greatly altered. These disturbances have been associated with adverse consequences, including increased mortality. Factors associated with the ICU environment, such as exposure to inadequate light and noise levels during the day and night or inflexible schedules of daily care activities, have been described as playing an essential role in sleep disturbances. The main objective of this study is to evaluate the impact of the use of a multifaceted environmental control intervention in the ICU on the quantity and quality of sleep, delirium, and post-intensive care neuropsychological impairment in critically ill patients. Methods: This is a prospective, parallel-group, randomized trial in 56 critically ill patients once they are starting to recover from their acute illness. Patients will be randomized to receive a multifaceted intervention of environmental control in the ICU (dynamic light therapy, auditory masking, and rationalization of ICU nocturnal patient care activities) or standard care. The protocol will be applied from enrollment until ICU discharge. Baseline parameters, light and noise levels, polysomnography and actigraphy, daily oscillation of plasma concentrations of Melatonin and Cortisol, and questionnaires for the qualitative evaluation of sleep, will be assessed during the study. In addition, all patients will undergo standardized follow-up before hospital discharge and at 6 months to evaluate neuropsychological impairment. Discussion: This study is the first randomized clinical trial in critically ill patients to evaluate the effect of a multicomponent, non-pharmacological environmental control intervention on sleep improvement in ICU patients. The results will provide data about the potential synergistic effects of a combined multi-component environmental intervention in ICU on outcomes in the ICU and long term, and the mechanism of action. Trial registration:, NCT. Registered on January 10, 2023. Last updated on 24 Jan 2023.
... The role of noise and other environmental factors with regard to sleep disorders have been widely discussed but the outcomes are inconsistent. We found three experimental studies (32)(33)(34) and one observational study (35) showing an association between exposure to noise and changes in sleep architecture as measured by PSG. These findings were refuted by three studies (36)(37)(38) stating that environmental factors are overestimated with regard to sleep disorders. ...
Full-text available
Objective:Sleep disruption is common in patients admitted in the intensive care unit (ICU), and it is associated with various negative effects. This study aimed to investigate whether the implementation of a multicomponent sleep protocol improved the quality of sleep, both subjectively (assessed with a questionnaire) and objectively (measured using actigraphy).Materials and Methods:A prospective interventional non-randomized controlled study compared two groups (PRE and POST groups) of 20 spontaneously conscious ICU patients.Results:Subjectively evaluated sleep quality was poor in the entire sample (n=40) [Richards-Campbell Sleep Questionnaire (RCSQ) total 49.2±25.1]. The mean total sleep time was 389.0±78.8 min, the Sleep Efficiency index (SEI) was 81.1±16.4%, and the number of awakenings per night was 18.4±9.79. The quality of sleep (both subjective and objective) was not significantly improved following the application of the sleep protocol (POST group), as inferred from most of the studied parameters. Subjective assessment yielded better results (RCSQ total: 45.1 PRE vs 51.1 POST); however, they were not statistically significant. Paradoxically, statistically significantly better results were observed for SEI (86.6% PRE vs 75.9% POST, p=0.044), total sleep time (416 min PRE vs 364 min POST, p=0.044), and noise (T=2.11, p=0.046) in the control group.Conclusion:Although the results failed to confirm that the multicomponent protocol exerted a significant effect, its implementation in clinical practice may be valuable. In a selected group of ICU patients, the proposed interventions may aid in achieving good sleep and in improving their overall comfort.
... A crossover clinical trial [20] tested the effect of earplugs and eye mask on the perceived sleep quality of patients in intensive care unit, and showed that the patients' nocturnal sleep quality enhanced in the night of wearing earplugs and eye mask. Hu et al. [21] found that earplugs and eye masks can play a positive role in improving sleep quality, promoting hormone balance and improving the level of REM sleep and nocturnal melatonin level in healthy subjects. ...
Full-text available
Medical students are vulnerable to sleep disorders, which could be further exaggerated by poor dormitory environment and roommate behaviour. However, there is little evidence of whether dormitory environment intervention is effective in improving the sleep quality of medical college students in developing countries. The present study aimed to evaluate the effects of a comprehensive multidomain intervention on dormitory environment and roommate behaviour among medical college students in China. In this cluster randomised controlled trial, a total of 106 dormitories (364 students) were randomly allocated into an intervention group (55 dormitories, 193 students) and a control group (51 dormitories, 171 students). The intervention group received a three-month intervention with multiple components to improve or adapt to sleep environments in dormitories; the control group received no intervention. Primary and secondary outcomes were measured at study enrolment and three months later for both groups. The linear mixed-effects models showed that, compared with the control group, the intervention was associated with a significantly decreased Pittsburgh Sleep Quality Index (β = −0.67, p = 0.012), and a marginally significant effect on reducing roommates’ influence on sleep schedule (β = −0.21, p = 0.066). Students in the intervention group rated “making dormitory sleep rules” and “wearing eye masks” as the most effective intervention measures. These findings could contribute to the limited body of scientific evidence about sleep intervention in Chinese medical students and highlight the importance of dormitory sleep environments in maintaining sleep quality.
Background and Aim: One of the most important problems of patients admitted to intensive care units (ICU) is their sleep quality. In these units, there are various visual and auditory discomfort factors that can negatively affect the outcome of the patient's treatment. The purpose of this study was to determine the effect of simultaneously using earplug and eye mask on the quality of sleep in hospitalized patients in the ICU. Method: This study was performed on 73 patients who had been admitted to the ICU of Ghaem Hospital and Imam Reza Hospital in 2016 in Mashhad. Patients were randomly assigned to control (n = 37) and test (n = 36) groups. The test group used an earplug and an eye mask during their night's sleep. Patients' sleep quality was assessed by using Voran-Schneider-Halper's questionnaire. Data were analyzed using SPSS16 software. Results: Independent t-test and Mann whitney U showed that before and after the intervention stage, no significant difference was observed between the test and control groups regarding the mean score of sleep quality. However, the results of Wilcoxon test showed a significant difference in the quality of sleep score in both groups before and after intervention (p <0.001). Conclusion: In this study, simultaneous use of earplug and eye mask was effective in improving the quality of sleep in patients admitted to the ICU. Therefore, this technique can be used as a simple, low-cost, and effective method in helping patients to prevent complications from sleep disorders.
Background: Noise and lighting are prime factors of poor sleep quality in critically ill patients, which impair recovery and increase the risk of delirium or complications. Aims: To identify and rank the effectiveness of sound and darkness interventions on the sleep quality of critically ill patients. Methods: This systematic review and component network meta-analysis was based on the Preferred Reporting Items for Systematic Reviews incorporating the Network Meta-Analyses (PRISMA-NMA) Statement. The Embase, MEDLINE, Cochrane CENTRAL, CINAHL, Airiti Library, and Google Scholar databases were searched from inception to August 10, 2021, for randomized controlled trials (RCTs) on sound and darkness interventions targeting critically ill patients' sleep quality. We applied standard and component NMA to determine the effects of interventions. The certainty of evidence was evaluated using the Cochrane risk-of-bias tool (V.2.0) and the online Confidence in Network Meta-Analysis (CINeMA) application. Results: Twenty-four RCTs with 1507 participants who used combined interventions constituting seven competing interventions were included in the standard NMA. The combination of earplugs, eye masks, and music; eye masks alone; earplugs combined with eye masks; and music alone had beneficial intervention effects. The combination of earplugs, eye masks, and music was the best intervention, and these components had no interaction effect. An eye mask had the best relative effect, followed by music, quiet time, and earplugs. Conclusions: This study provides clinical evidence of the effectiveness of using eye masks, music, and earplugs to improve sleep quality in critically ill patients. We also recommend future research using bedtime music, nocturnal eye masks, and quiet time, which had the best relative effects on sleep quality. Relevance to clinical practice: This study provides recommendations for interventions that nurses can use to improve critically ill patients' sleep quality.
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.
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.
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.
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.