Improvement of ICU sound environment and analyses of consequences on sleep - an experimental study

Abstract

Objective: Uninterrupted sleep is of vital importance for restoration and regaining health. In intensive care units (ICU) where recovering and healing is crucial, patients’ sleep is often fragmented and disturbed due to noise from activities from personal, other patients and alarms. The aim of this study was to explore if sleep could be improved by modifying the sound environment in a way that is practically feasible in an ICU. Methods: The effects of originally recorded ICU noise and peak reduced ICU noise on sleep in healthy male subjects was studied. Sleep was registered with polysomnography (PSG) during four nights: one adaptation night, one reference night and the two exposed nights with similar equivalent sound levels (47 dB LAeq) but different maximum sound levels (56 vs 64dB LAFmax). The subjects answered questionnaires and saliva cortisol were sampled in the morning. Results: During ICU exposure nights, sleep was more fragmented with less slow wave sleep, more arousals and more time awake. The effects of reduced maximum sound level were minor. The subjective data supported the polysomnographical findings while cortisol levels were not significantly affected by the exposure conditions. Conclusions: Intensive care noise impairs sleep and the reduction of maximal A-weighted levels from 64 dB to 56 dB is not enough to have a clear improved effect on sleep quality.