Can ICUs create more sleep by creating less noise?

Excerpt

“True silence is the rest of the mind,

and is to the spirit

what sleep is to the body,

nourishment and refreshment.”

William Penn

In 1974 and 1999, respectively, the US Environmental Protection Agency (EPA) and World Health Organization (WHO) published landmark guidelines for public noise [1], mandating that daytime and nighttime hospital noise, defined as “unwanted sound”, average less than 35–45 and 30–35 decibels (dB, i.e., a typical library), respectively, and nighttime peaks not exceed 40–45 dB (i.e., a normal conversation and threshold to maintain sleep). More recently the European community published an updated directive as well [2]. Compliance with these guidelines is poor, particularly in ICUs as alarming machines, staff conversations, bedside visitors, and routine activities such as supply restocking and floor waxing routinely push noise levels above 80 dB (i.e., a garbage disposal) [1]. Sound intensity in ICUs has increased over time, doubling (4 dB on logarithmic scale) each decade and rising 16-fold since 1960 [1]. Recent studies have shed new knowledge on noise, specifically that (a) sound level changes may be more disruptive than continuous sounds, in particular those arising from lower (vs higher) baseline sound levels [3]; (b) the vast majority of sound pollution originates from a small area near patients’ ears [4]; and (c) unwanted sounds are often due to staff conversations, the majority of which are unrelated to patient care, and alarms, of which 90% are non-beneficial “false positives” (Fig. 1)  [5].

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