Brown University News Bureau

The Brown University News Bureau

1996-1997 index

Distributed January 14, 1997
Contact: Scott Turner

Quiet: hospital zone

Hospital noise disrupts sleep for patients in the critical care setting

Excessive noise pollution at night may be an important cause of sleep disruption in hospitalized elderly patients. For years, patients have complained that noise disturbs their sleep. New findings offer direct evidence that environmental noise in the hospital correlates strongly with sleep disruption.

PROVIDENCE, R.I. -- There is no rest for weary hospital patients.

A new study shows a very strong relationship between the number of loud sounds - 80 decibels or greater - and sleep arousals among elderly patients in a hospital's intermediate respiratory care unit. A loud beeper could produce an 80-decibel sound.

"During an eight-hour period, from 10 p.m. to 6 a.m., we found that loud noises markedly disrupted the sleep of patients," said Richard Millman, M.D., one of the study's authors. Millman is professor of medicine at Brown University and director of the Sleep Disorders Clinic at Rhode Island Hospital. "The patients spent a huge percentage of the time awake during the night."

The authors suggest that hospitals modify the sounds produced in the critical care setting and find ways to screen patients from noise pollution. The sounds came from various sources, such as loud voices, televisions, equipment alarms, intercoms and beepers.

For the study, medical personnel at Brown University monitored overnight the link between peak sound levels and arousals from deep sleep in six elderly patients. They found a very strong correlation between the number of sound peaks and sleep arousals. For example, not counting interruptions by nurses or doctors, the researchers found 29 peak sound levels were associated with 28 sleep arousals in one patient during a one-hour period. In another patient, 34 sound peaks were correlated with 42 arousals in one hour.

Medical personnel aren't sure how disrupted sleep affects elderly patients. Some studies show that at least one-third of sleep-deprived hospital patients have what is called "ICU psychosis," marked by symptoms of nighttime disorientation and delusion. Sleep deprivation may also adversely affect respiratory muscle function, possibly hindering weaning from mechanical ventilators, Millman said.

The study appears in the current issue of the journal Sleep. Although noise pollution in hospitals has been recognized for years, there has been no concerted effort to correct it, Millman said.

In fact, the study's findings are part of a larger problem. Some of Millman's previous research showed that peak sound levels in a hospital during a 24-hour period were consistently above 70 decibels. The sources of this excessive noise need to be better identified so that attempts can be made to reduce the sound to more acceptable levels, he said.

Millman suggests that hospitals redesigning or constructing critical care settings use the study's findings to create sites that minimize noise pollution such as arranging patients in individual rooms. Other ways to reduce noise are to move equipment alarms away from patients, relocate nurse's stations away from rooms, switch beepers to vibrating mode and train doctors and nurses to speak more softly. An alternative approach may be to determine if the use of ear plugs or noise cancellation equipment leads to better sleep quality in patients, he said.

The peak sound level recommended for hospitals by the Environmental Protection Agency is 45 decibels during the day and 35 decibels at night.