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Critical care unit noise and rapid eye movement (REM) sleep
Objective:
To determine if Critical Care Unit (CCU) sound levels suppress rapid eye movement (REM) sleep.
Design:
Posttest-only control group experimental design.
Setting:
Sleep laboratory located in a university neurologic institute.
Subjects:
Seventy paid ($40) women who had no hearing or sleep problems.
Procedures:
Subjects were randomly assigned to a noise or quiet (control) group while attempting to sleep overnight in the laboratory. Noise-condition subjects heard an audiotape recording of CCU nighttime sounds. The audiotape recording was withheld from the control group.
Results:
Subjects in the noise condition showed poorer REM sleep on seven of 10 measures. These included REM activity and shorter REM durations throughout the night and during the first and second halves of the night as well as a longer interval between the first and second REM cycles. The majority of the t test results were significant at the 0.001 level or better.
Conclusions:
Although generalization of the results to CCU patients is limited (because of the use of laboratory subjects), the results provided convincing support for a causal relationship between CCU sound levels and suppression of REM sleep.