Table 4.

Recent Intervention Studies Related to Environmental Impact on Sleep Disturbance (1999–2010)

Study	Participants	Intervention	Measures	Results/Conclusions
Dennis et al., 201092	50 neuro-ICU patients, 35 observed during day hours and 15 observed during night hours.	Quiet time, a period of reduced controllable noise and light, took place twice daily coinciding with circadian rhythms.	Noise and light levels: measured at multiple locations before, during, and after quiet time hours. Sleep behavior was recorded every ½ hour, beginning 30 min before quiet time until 30 minutes after.	Results demonstrated significantly lower noise and light levels during day shift quiet time. Patients were significantly more likely to be observed sleeping during day shift quiet time hours.
Hu et al., 201088	14 healthy participants exposed to ICU noise and light.	Use of earplugs and eye masks.	Sleep: assessed via polysomnography under four conditions: adaptation, baseline, exposure to recorded ICU noise and light (NL), and NL plus use of earplugs and eye masks (NLEE).	Participants had poorer perceived sleep quality, more light sleep, longer REM latency, less REM sleep when exposed to simulated ICU noise and light. Nocturnal melatonin and cortisol secretion levels differed significantly by condition but not anxiety levels. Use of earplugs and eye masks resulted in more REM time, shorter REM latency, less arousal and elevated melatonin levels. Earplugs and eye masks enhanced sleep and hormone balance in healthy subjects exposed to simulated ICU noise and light, suggesting their use in ICU patients may be reasonable.
Monsen & Edell- Gustafsson, 2005123	No participants – study examined disturbance factors and noise levels in a neuro ICU before and after a behavior program to limit disturbances and noise.	A behavioral modification program: changing nursing and medical routines and the introduction of afternoon and night non-disturbance periods.	Sleep disturbance factors and noise level were measured during two weeks before (M1) and after (M2) the implementation of the behavioral modification program and non-disturbance periods.	The greatest sleep disturbing factors at both M1 and M2 were general nursing care activities. Noise levels showed great variation at both M1 and M2. Implementation of a behavioral modification program and non-disturbance periods coordinated routines resulted in reduced sleep disturbance factors and partly reduced noise levels on the neuro ICU. Results suggest changes of the physical care/working environment, preparations before non-disturbance periods, regular evaluations of routines and education are needed to improve sleep on neuro ICUs.
Olson et al., 2001120	239 neuro ICU patients: 118 patients in the control group; 121 patients in the intervention group.	“Quiet-time” protocol to reduce environmental stimuli: sounds and lights were decreased from 2 AM to 4 AM and from 2 PM to 4 PM.	Sleep observation: Glasgow Coma Scale	The percentage of patients observed asleep was significantly higher during the months the quite- time period was implemented than during the control period before the intervention was started. The increase in sleep behavior was associated with decreased sound and light levels during the quiet time. Patients observed during the intervention period were more likely to be asleep during the quiet time than were patients observed during the control period. Results suggest a concentrated effort by staff to reduce environmental stimuli at discrete preset intervals increases the likelihood of sleep during scheduled quiet time in a neuro ICU.
Richardson et al., 2007124	64 cardiothoracic critical care unit (CCU) patients consented; 34 patients tried earplugs and eye masks.	Eye masks and earplugs to control patients’ exposure to noise and light within the CCU environment.	Sleep assessment rating scales and open-ended questions were used to obtain patients’ reported experiences of their sleep. Patients self- selected into either an intervention or non- intervention group.	Many patients who used the earplugs and eye masks found they improved sleep, however, noise was still a factor preventing sleep for both groups of patients. Mixed reports were found with the interventions from very comfortable to very uncomfortable. Investigators concluded that offering patient’s earplugs and eye masks to improve sleep is an inexpensive intervention that may be considered as a matter of routine nursing practice. This should include time to show patients how to use and try them out for comfort.
Scotto et al., 2009125	88 ICU patients (non-ventilated, non-sedated); 49 intervention/39 control.	Earplugs.	Subjective sleep was assessed via Verran- Snyder-Halpern Sleep Scale, an 8-question visual analogue scale.	Earplug use improved the subjective experience of sleep for un-medicated critical care patients without interfering with care delivery. Authors concluded 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.
Stanchina et al., 200589	Four healthy volunteers	White noise added to the sleep environment.	Sleep was measured by polysomnography. Baseline and peak noise levels were recorded for each arousal from sleep during exposure to recorded ICU noise, and exposure to ICU noise with mixed- frequency white noise.	A total of 1178 arousals were recorded. Compared to the baseline night, the arousal index increased during the noise but not the white noise/ICU noise night. 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. 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.
Walder et al., 200090	Critically ill adult patients admitted to a surgical ICU, subdivided into six identical three-bed rooms.	Between two observation periods, five guidelines were implemented to decrease both light and noise during the night shift in the patient’s room.	Light levels and noise levels were obtained using a luxmeter and a sound level meter [A- weighted decibels (dB) scale] and were monitored continuously from 11 pm to 5 am both before (P1) and after (P2) the implementation of guidelines.	The implementation of guidelines lowered mean light disturbance intensity with a greater variability of light during P2. The night light levels were low during both periods, and lowering the light levels induced a greater variation of light, which may impair sleep quality. All measured noise levels were high during both periods, which could contribute to sleep disturbance, and the implementation of guidelines significantly lowers some important noise levels. The background noise level was unchanged.
Wallace et al., 1999126	6 paid, healthy volunteers at 7-day intervals in a sleep disorders center exposed to simulated ICU noise.	After the first 3 quiet nights, earplugs were randomly assigned to be worn on the fourth and fifth nights during exposure to the recorded ICU noise.	Sleep was measured by polysomnography.	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, REM latency and decreased time asleep, sleep maintenance efficiency index, and percentage of rapid REM sleep. Earplugs worn during exposure to the noise produced a significant decrease in REM latency and an increase in the percentage of REM sleep. The results provide a reasonable basis for testing the effects of earplugs on the sleep of critically ill subjects.