Observations of Acoustic Interruptions Versus Ambient Sound Levels With Perceived Sleep Quality During Critical Illness

ICUs are loud and there is an association between ambient sound and worsened sleep quality. In contrast to ambient sound, short acoustic interruptions or sound spikes—for example, brief alarm tones—cause arousal from sleep in healthy patients, but remain understudied in critically ill patients, despite the observed frequency of ICU alarms. We collected greater than 2.3 million values of ambient sound (every second) among 14 patients in the ICU over a median of two nights (interquartile range, 1–2) each. We identified brief acoustic interruptions/sound spikes—increases of greater than or equal to 20 dB above ambient—over 1 second. Patients experienced a median of five interruptions greater than or equal to 20 dB (interquartile range, 2–12) per night. Each interruption was associated with a 1-point decrease in patient reported quality of sleep, as assessed by the Richards Campbell Sleep Questionnaire. Our observations suggest a possible relationship between acoustic interruptions and worsened perceived sleep.