Sound and Light Levels in a General Intensive Care Unit Without Windows to Provide Natural Light.

Abstract

Background: Appropriate levels and patterns of sound and light in an intensive care room help to maintain the patient's normal physiological functions. High sound levels can disrupt the patient's normal sleep architecture, cause hearing deficits, and induce the onset of delirium. Intensive care unit patients frequently report poor sleep, partly due to the environment.

Objectives: An observational pilot prospective study was designed to record sound pressure and light pollution levels in an Italian intensive care unit, without windows to provide natural light.

Method: Sound levels were measured in decibel A (dBA) every 10 seconds. Sound data were analyzed for sound peak, defined as the number of times sound levels exceeded 45, 50, 60, 65, 70, 75, 80, and 85 dBA. Light measures were taken every 10 seconds on a continuous basis. Light data were analyzed for light "peaks," defined as the number of times light levels exceeded 100, 200, 300, 400, and 500 lux.

Results: The overall median sound level during the study period was equal to 54.60 (interquartile range [IQR], 51.70-57.70) dBA. The daytime median sound level was 56.00 (IQR, 53.00-59.50) dBA, and the nighttime median was 53.00 (IQR, 49.50-55.20) dBA (P < .001). The overall median light level was equal to 114 (IQR, 0-225) lux. The daytime median light level was 184 (IQR, 114-293) lux, and the nighttime median was 0 (IQR, 0-50) lux (P < .001). With respect to room lighting, rooms were observed to have "no lights on" 12.6% of daytime and 41% of nighttime.

Discussion: The sound levels recorded in our sample demonstrated that peaks >45 dBA during daytime and nighttime are, respectively, equal to 99.9% and 98.6% of all readings. The Environmental Protection Agency/World Health Organization recommended thresholds for both day (45 dBA) and night (35 dBA). Sound levels reached "toxic levels" when sound-generating activities were performed by nurses and physicians.