The influence of white noise on sleep in subjects exposed to ICU noise
ABSTRACT There is disagreement in the literature about the importance of sleep disruption from intensive care unit (ICU) environmental noise. Previous reports have assumed that sleep disruption is produced by high-peak noise. This study aimed to determine whether peak noise or the change in noise level from baseline is more important in inducing sleep disruption. We hypothesized that white noise added to the environment would reduce arousals by reducing the magnitude of changing noise levels.
Four subjects underwent polysomnography under three conditions: (1) baseline, (2) exposure to recorded ICU noise and (3) exposure to ICU noise and mixed-frequency white noise, while one additional subject completed the first two conditions. Baseline and peak noise levels were recorded for each arousal from sleep.
A total of 1178 arousals were recorded during these studies. Compared to the baseline night (13.3+/-1.8 arousals/h) the arousal index increased during the noise (48.4+/-7.6) but not the white noise/ICU noise night (15.7+/-4.5) (P<0.004). The change in sound from baseline to peak, rather than the peak sound level, determined whether an arousal occurred and was the same for the ICU noise and white noise/ICU noise condition (17.7+/-0.4 versus 17.5+/-0.3 DB, P=0.65).
Peak noise was not the main determinant of sleep disruption from ICU noise. Mixed frequency white noise increases arousal thresholds in normal individuals exposed to recorded ICU noise by reducing the difference between background noise and peak noise.
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ABSTRACT: Sleep is one of the basic human needs and sleep deprivation causes numerous undesirable effects on the human body and mind, especially in the intensive care unit (ICU) patients. It seems that noise and light are important environmental factors interrupting sleep in these patients. This study was carried out to determine the effect of earplugs and eye mask on Iranian patients' sleep quality in ICU. In this cross-over clinical trial, 50 patients in the ICUs of Al-zahra Medical Center in Isfahan in 2012 were selected by convenient sampling method and randomly assigned to two groups. In group A, patients wore earplugs and eye mask in the first night during their sleep and slept without earplugs and eye mask in the second night, and the intervention was conversely conducted in group B. Verran and Snyder-Halpern Sleep Scales were used to measure the patients' sleep quality. The data were analyzed by paired t-test, independent t-test, one-sample t-test, and one-way analysis of variance (ANOVA) through SPSS version 18. Effect of the intervention on sleep effectiveness was positive, and there were significant differences (P < 0.001) between treatment night and control night, and also within each group (P < 0.001). Effect of the interventions on sleep disturbance was positive, and there was a significant difference at treatment night compared to the control night between groups and within each group (P < 0.001). Also, the mean scores for sleep supplementation were measured after the second night, and the results showed the scores significantly increased in the intervention group compared to the control group (P < 0.001, ER = 47, F = 22.1). In addition, carryover effects for sleep efficiency and sleep disturbance were positive, but periodic effects for sleep efficiency and sleep disturbance were negative and positive, respectively. : Although wearing earplugs and eye mask is a cost-effective and safe method and can improve perceived sleep quality in ICU patients, further research is needed to demonstrate the effect of this method.Iranian journal of nursing and midwifery research 11/2014; 19(6):673-8.
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ABSTRACT: Sleep deprivation is common in critically ill patients in the intensive care unit (ICU). Noise and light in the ICU and the reduction in plasma melatonin play the essential roles. The aim of this study was to determine the effect of simulated ICU noise and light on nocturnal sleep quality, and compare the effectiveness of melatonin and earplugs and eye masks on sleep quality in these conditions in healthy subjects. This study was conducted in two parts. In part one, 40 healthy subjects slept under baseline night and simulated ICU noise and light (NL) by a cross-over design. In part two, 40 subjects were randomly assigned to four groups: NL, NL plus placebo (NLP), NL plus use of earplugs and eye masks (NLEE) and NL plus melatonin (NLM). 1 mg of oral melatonin or placebo was administered at 21:00 on four consecutive days in NLM and NLP. Earplugs and eye masks were made available in NLEE. The objective sleep quality was measured by polysomnography. Serum was analyzed for melatonin levels. Subjects rated their perceived sleep quality and anxiety levels. Subjects had shorter total sleep time (TST) and rapid eye movement (REM) sleep, longer sleep onset latency, more light sleep and awakening, poorer subjective sleep quality, higher anxiety level and lower serum melatonin level in NL night (P <0.05). NLEE had less awakenings and shorter sleep onset latency (P <0.05). NLM had longer TST and REM and shorter sleep onset latency (P <0.05). Compared with NLEE, NLM had fewer awakenings (P = 0.004). Both NLM and NLEE improved perceived sleep quality and anxiety level (P = 0.000), and NLM showed better than NLEE in perceived sleep quality (P = 0.01). Compared to baseline night, the serum melatonin levels were lower in NL night at every time point, and the average maximal serum melatonin concentration in NLM group was significantly greater than other groups (P <0.001). Compared with earplugs and eye masks, melatonin improves sleep quality and serum melatonin levels better in healthy subjects exposed to simulated ICU noise and light. Chinese Clinical Trial Registry ChiCTR-IPR-14005458 . Registered 10 November 2014.Critical care (London, England) 12/2015; 19(1):842. DOI:10.1186/s13054-015-0842-8
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ABSTRACT: Excessive noise is becoming a significant problem for intensive care units (ICUs). This paper first reviews the impact of noise on patients’ sleep in ICUs. Five previous studies have demonstrated such impacts, whereas six other studies have shown other factors to be more important. Staff conversation and alarms are generally regarded as the most disturbing noises for patients’ sleep in ICUs. Most research in this area has focused purely on noise level, but work has been very limited on the relationships between sleep quality and other acoustic parameters, including spectrum and reverberation time. Sound-absorbing treatment is a relatively effective noise reduction strategy, whereas sound masking appears to be the most effective technique for improving sleep. For future research, there should be close collaboration between medical researchers and acousticians.