Clinical question: While it is generally thought that ICU wards are not conducive for sleep because of light and noise disruptions, are general wards any better?
Background: Hospitalized patients frequently report poor sleep, partly because of the inpatient environment. Sound level changes (SLCs), rather than the total volumes, are important in disrupting sleep. The World Health Organization recommends that nighttime baseline noise levels do not exceed 30 decibels (dB) and that nighttime noise peaks (i.e., loud noises) do not exceed 40 dB. The circadian rhythm system depends on ambient light to regulate the internal clock. Insufficient and inappropriately timed light exposure can desynchronize the biological clock, thereby negatively affecting sleep quality.
Dr. James S. Kim
Study design: Observational study.
Setting: Tertiary care hospital in La Jolla, Calif.
Synopsis: For approximately 24-72 hours, recordings of sound and light were performed. ICU rooms were louder (hourly averages ranged from 56.1 dB to 60.3 dB) than were non-ICU wards (44.6-55.1 dB). However, SLCs of 17.5 dB or greater were not statistically different (ICU, 203.9 ± 28.8 times; non-ICU, 270.9 ± 39.5; P = .11). In both ICU and non-ICU wards, average daytime light levels were less than 250 lux and generally were brightest in the afternoon. This corresponds to low, office-level lighting, which may not be conducive for maintaining circadian rhythm.
Bottom line: While ICU wards are generally louder than non-ICU wards, sound level changes are equivalent and probably more important concerning sleep disruption. While no significant differences were seen in light levels, the amount and timing of lighting may not be optimal for keeping circadian rhythm.
Citation: Jaiswal SJ et al. Sound and light levels are similarly disruptive in ICU and non-ICU wards. J Hosp Med. 2017 Oct;12(10):798-804.
Dr. Kim is assistant professor of medicine in the division of hospital medicine, Emory University, Atlanta.