Effect
of Occupational Noise on the Nocturnal
Sleep Architecture of Healthy Subjects
B. Gitanjali* and R. Dhamodharan
Sleep Disorders Laboratory,
Department of Pharmacology,
Jawaharlal Institute of Postgraduate Medical Education & Research,
Pondicherry – 605 006
( Received on April 6, 2003 )
click
here for full article in pdf
Abstract
Background & objectives : Noise is considered
to be a non-specific stressor which generally causes physiological
and psychological effects in an individual. Many occupations involve
workers being subjected to loud noise levels without adequate
protective measures. The study was done to document the changes,
if any, in the nocturnal sleep architecture of healthy persons
exposed to loud occupational noise during daytime.
Methods : The study was a retrospective cohort
design wherein three groups of eight subjects each, exposed to
continuous occupational background noise levels of >75dB for
1–2 years, 5–10 years and >15 years were selected.
Corresponding age and gender matched healthy controls (eight for
each group) who worked in a quiet atmosphere was also recruited.
All night sleep polysomnography was done on all subjects. In the
morning, subjects rated their quality of sleep on a Visual Analogue
Scale.
Results : There is a strong association between
occupational exposure to loud noise and poor sleep efficiency
(Relative Risk 2.49; Confidence Interval 1.12 to 5.57; P=0.01,
Fisher’s exact test). The group exposed to noise for 1–2
years had a decrease in Total Rapid Eye Movement Time, Non Rapid
Eye Movement Time, Slow Wave Sleep Time, Sleep Onset Latency and
Total Sleep Time. The other two groups showed lesser number of
changes in sleep architecture. Subjectively there was a decrease
for sleep continuity in Group I and an increase for sleep onset
in Group II. There is no correlation between loudness of noise
in the workplace and sleep efficiency.
Interpretation & conclusion : It can
be concluded that workers exposed to loud background occupational
noise are at an increased risk of having poor quality sleep but
adaptation to this effect probably takes place after a few years.
