Hospital Noise Results in Significant Patient Sleep Loss

Jennifer Garcia

January 09, 2012

January 9, 2012 — Higher than recommended noise levels in patient rooms is associated with clinically significant sleep loss among hospitalized patients, and may impede patient recovery, according to results of a new study published online January 9, 2012, in the Archives of Internal Medicine.

Jordan Yoder, BSE, from the Pritzker School of Medicine, University of Chicago, Illinois, and colleagues found that noise level all days during the 155-day study period exceeded the World Health Organization (WHO) recommendations for average hospital-room noise levels of 30 dB (mean average sound level, 48.0 dB; 95% confidence interval [CI], 47.2 - 49.5 dB), and the peak noise approached that of a chainsaw (80.3 dB; 95% CI, 78.5 - 82.2 dB), which is well over the recommended maximum of 40 dB.

Although nights were generally quieter than daytime hours, they still exceeded the recommendations, with a mean maximum sound level of 69.7 dB (95% CI, 68.1 - 71.3 dB). In addition, 94% of the nights exceeded recommendations for average noise levels (mean average noise level, 38.2 dB; 95% CI, 36.9 - 39.4 dB).

Staff conversation (65%), roommates (54%), alarms (42%), intercoms (39%), and pagers (38%) were the most common sources of noise disruption reported by patients.

When the authors objectively measured sleep, using actigraphy data, they found that disruptions of sleep resulting from noise were reported by 42% of patients in the hospital. Patients also reported sleeping significantly less while in the hospital than their baseline sleep level (314 minutes vs 382 minutes; P = .002). Sleep efficiency, which is the number of minutes of sleep divided by the number of minutes in bed, also suffered, according to the researchers, with a mean sleep efficiency of 73.3% (95% CI, 70.3% - 76.4%).

Patients exposed to the loudest tertile of average nighttime noise levels (mean, 50 dB) slept an average of 76 minutes less (95% CI, −134 to −18 minutes; P = .01) than those patients exposed to the quietest tertile of average nighttime noise levels (mean, 43.3 dB).

"Despite the importance of sleep for recovery, hospital noise may put patients at risk for sleep loss and its associated negative effects," the authors write. They also note that hospital noise may be as high as 67 dB in the intensive care unit, or 42 dB in surgical wards, which greatly exceed the 30-dB WHO recommendation for patient rooms.

Between April 2010 and May 2011, 106 patients were enrolled in the study. Patients were older than 50 years (mean age, 66 years), and those patients with a known sleep disorder or cognitive impairment or who were under respiratory isolation or hospitalization for more than 72 hours were excluded. Patients enrolled in the study were predominantly women (51%) and black (63%).

Sleep quality was assessed using the Pittsburgh Sleep Quality Index, and sleepiness was evaluated using the Epworth Sleepiness Scale. Sound level monitors were used to record bedside noise levels, and objective sleep data were obtained with wrist activity monitors. The association between nighttime noise and sleep duration and efficiency was statistically evaluated, using linear regression models.

The study results demonstrate that hospital noise levels can be detrimental to sleep quality and efficiency; however, the source of much of that noise can be modified. "Hospitals should implement interventions to reduce nighttime noise levels in an effort to improve patient sleep, which may also improve patient satisfaction and health outcomes," note Mr. Yoder and colleagues.

Support for the study was provided by the National Institute on Aging through a Short-Term Aging-Related Research Program, a National Institute on Aging career development award, a midcareer development award, a Program Project, and the Agency for Healthcare Research and Quality Centers for Education and Research on Therapeutics. The authors have disclosed no relevant financial relationships.

Arch Intern Med. Published online January 9, 2012.

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