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


CONCLUSIONS
The results provide a reasonable basis for testing the effects of earplugs on the sleep of critically ill subjects.
Division of Pulmonary Medicine, LDS Hospital, Salt Lake City, UT, USA.
C J
CJ
Wallace
J
J
Robins
L S
LS
Alvord
J M
JM
Walker
D000328:Adult; D015400:Clinical Nursing Research; D003422:Critical Care / Q000379:methods; D004430:Ear Protective Devices / Q000592:standards*; D005240:Feasibility Studies; D006272:Health Facility Environment; D006785:Hospitals, University; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D009622:Noise / Q000009:adverse effects*; D017286:Polysomnography; D012892:Sleep Deprivation; D012894:Sleep Stages; D013637:Tape Recording; D013997:Time Factors; D014589:Utah