The effect of earplugs on sleep measures during exposure to simulated intensive care unit noise

Abstract

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.

Sound Pressure Levels in 2 Veterinary Intensive Care Units

“…3,7,10,15,16 The causal relationship between noise and sleep has been identified using both objective (polysomnography) and subjective (patient self-reports) measures. 7,21,23,[33][34][35][36] Sleep disruption in the ICU is multifactorial, with extrinsic (eg noise, light, treatment interventions, temperature) and intrinsic (eg patient factors: pain, anxiety, disease) sources. [3][4][5]12,37 Noise is a major cause of sleep disruption in the ICU, responsible for 17-53% of awakenings and arousals depending on the patient population and reporting methods.…”

“…5,7,10 Whenever interventions to decrease noise exposure have been introduced, sleep quality has improved. 21,[33][34][35][36] Interventions have included ear plugs, changes in staff behavior, decreasing alarm and telephone volumes and sound masking (addition of other sound such as ocean sounds). The use of acoustic absorbing material has been shown to substantially decrease environmental sound levels by approximately 3 dBA and may be simpler to implement than achieving sustained change in human behavior.…”

Earplugs improve patients’ subjective experience of sleep in critical care

“…The subjects wore earplugs during nocturnal sleeping sessions. The researchers reported a significant increase in REM sleep, an increase in percentage of NREM sleep and sleep efficiency and a decrease in difficulty falling asleep (Wallace et al, 1999).…”

Earplugs and eye masks: do they improve critical care patients’ sleep?

“…This study highlighted the important link with a reduction in REM sleep and signs of confusion, suspiciousness, withdrawal and poorer recall (Topf and Davis, 1993). Likewise, Wallace et al (1999) found that exposure to critical care noises increased the number of awakenings and decreased sleep time. An early study reported on excess noise and the effects on sleep within critical care, the average night-time noise was recorded at 56 decibel units dB(A), with maximum peaks of 86 dB(A) (Topf, 1992).…”

“…Disturbances at night-time have been reported, through patient satisfaction surveys, as one of the causes of inpatient dissatisfaction while in hospital (Commission for Patient and Public Involvement in Health, 2007). As well as the reported patients' experiences of disturbed sleep, sleep deprivation has been well researched, particularly how common this is in patients in acute care settings (Parker, 1995;Wallace et al, 1999;Cooper et al, 2000;Redeker, 2000). This sleep deprivation is scientifically supported by polysomnographic studies (Honkus, 2003).…”