ENVIRONMENTAL NOISE AS A CAUSE OF SLEEP DISRUPTION IN AN INTERMEDIATERESPIRATORY CARE UNIT

Our laboratory previously reported continuously monitored peak sound l evels in several areas at Rhode Island Hospital. The number of sound p eaks greater than 80 A-weighted decibels (dBA) was found to be high in the intensive and intermediate respiratory care unit (IRCU) areas, ev en at night. Environmental noise of this magnitude is potentially slee p-disruptive. Therefore, we hypothesized that nocturnal peak sound lev els of greater than or equal to 80 dBA would be associated with an inc rease in EEG arousals from sleep in patients in the IRCU. Six patients underwent sleep monitoring while environmental peak sound levels were continuously recorded. Each 8-hour period (2200 to 0600 hours) was br oken down into 30-minute segments. If there were 10 minutes or more of wakefulness in a segment, that segment was dropped from further analy sis. Of the remaining 61 segments, there was a very strong correlation (r = 0.57, p = 0.0001) between the number of sound peaks of greater t han or equal to 80 dBA and arousals from sleep. These 61 periods were then classified as quiet, moderately loud, and very loud based on the number of sound peaks (less than or equal to 5, 6-15, and >15, respect ively). Analysis of variance revealed a significant difference between the number of arousals (p = 0.001) in quiet periods and that in very loud periods. We conclude that environmental noise may be an important cause of sleep disruption in the IRCU.