Hospital Nighttime Noises Slow Patient Healing

A new study claims that nighttime noise in hospitals such as overhead paging, intravenous (IV) alarms, and squeaky carts add up to fractured sleep, interrupting healing when patients need it most.

Researchers at Harvard University (Boston, MA, USA) and Brigham and Women's Hospital (Boston, MA, USA) conducted a study that included 12 healthy adults who slept in a sound-dampened sleep lab for polysomnography over three nights. After a run-in night, the participants were exposed to 14 common sounds, such as voices, IV alarm, phone, ice machine, toilet flush, laundry cart, outside traffic, and helicopter noise, that were played at levels increasing from 40 dB to 70 dB during specific sleep stages.

The researchers found that electronic alert sounds like ringing phones and IV alarms were the most "potent" in arousing sleepers, disrupting normal sleep brain wave patterns more than half of the time, even when set at their quietest settings. Staff talking and voice paging at a level of 50 dB--quieter than normal conversation--disrupted sleep half of the time. Sleep was easier to disrupt in the phase after the transition into sleep, called N2, that adults spend most of their time asleep in, compared with the next deeper, slow-wave sleep phase called N3 or the rapid eye movement (REM) phase. The study was published in the June 19, 2012, issue of the Annals of Internal Medicine.

“These results likely underestimated the impact of noise on sleep among inpatients due to the young population studied, whereas the typical hospitalized patient is older with medical and psychiatric conditions, as well as pain and medication use, all of which contribute to a harder time reaching the deep N3 stage of sleep,” cautioned lead author Orfeu Buxton, PhD, and colleagues.

“Another limitation in that regard was that noise exposure was sequential, kept to 10 seconds or less, and halted if a participant started to wake up, which is not the case in a real hospital setting.”

Noise is a publicly reported quality measure for US hospitals, and as a result many hospitals have started to implement various strategies to limit night noise, such as putting posters or stoplight-style monitors in hallways to remind staff and visitors to keep voices down, installing a switch to activate visual paging systems, and setting up "quiet time" hours.

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Harvard University
Brigham and Women's Hospital