Effect of occupational noise on the nocturnal sleep architecture of healthy subjects.

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.

[1]  S. Stansfeld,et al.  Noise, noise sensitivity and psychiatric disorder: epidemiological and psychophysiological studies. , 1993, Psychological medicine.

[2]  Warren C. Stern,et al.  Theoretical view of REM sleep function: maintenance of catecholamine systems in the central nervous system. , 1974, Behavioral biology.

[3]  T. Kawada,et al.  Change in rapid eye movement (REM) sleep in response to exposure to all-night noise and transient noise. , 1999, Archives of environmental health.

[4]  P. O’Connor,et al.  Influence of Exercise on Human Sleep , 1995, Exercise and sport sciences reviews.

[5]  J S Augenstein,et al.  Noise raises blood pressure without impairing auditory sensitivity. , 1981, Science.

[6]  J. Siegel,et al.  A function for REM sleep: regulation of noradrenergic receptor sensitivity , 1988, Brain Research Reviews.

[7]  J Luz,et al.  Noise exposure, noise annoyance and their relation to psychological distress, accident and sickness absence among blue-collar workers--the Cordis Study. , 1992, Israel journal of medical sciences.

[8]  Wolfgang Babisch,et al.  Epidemiological Studies of the Cardiovascular effects of Occupational Noise - A Critical Appraisal. , 1998, Noise & health.

[9]  Y. Kurokawa,et al.  Self-reported sleep quality, job stress, and daytime autonomic activities assessed in terms of short-term heart rate variability among male white-collar workers. , 1998, Industrial health.

[10]  Francis Crick,et al.  The function of dream sleep , 1983, Nature.

[11]  Carlyle Smith,et al.  Sleep states and learning: A review of the animal literature , 1985, Neuroscience & Biobehavioral Reviews.

[12]  S M Abel,et al.  The extra-auditory effects of noise and annoyance: an overview of research. , 1990, The Journal of otolaryngology.

[13]  W C Dement,et al.  Sleep and aging. , 1980, Sleep.

[14]  E. Wolpert.  A Manual of Standardized Terminology, Techniques and Scoring System for Sleep Stages of Human Subjects. , 1969 .

[15]  A. Karni,et al.  Dependence on REM sleep of overnight improvement of a perceptual skill. , 1994, Science.

[16]  S. Dwivedi.  Effect of Ocimum sanctum linn on noise induced changes in plasma corticosterone level. , 1997, Indian journal of physiology and pharmacology.

[17]  M. Bertini,et al.  A complementary relationship between wake and REM sleep in the auditory system: a pre-sleep increase of middle-ear muscle activity (MEMA) causes a decrease of MEMA during sleep , 2000, Experimental Brain Research.

[18]  G. Evans,et al.  Stress and open-office noise. , 2000, The Journal of applied psychology.

[19]  A. Tilley,et al.  REM sleep and memory consolidation , 1978, Biological Psychology.

[20]  G. Vogel,et al.  Improvement of depression by REM sleep deprivation. New findings and a theory. , 1980, Archives of general psychiatry.

[21]  P. Hauri,et al.  Reverse first night effect in insomnia. , 1989, Sleep.

[22]  I. Hindmarch,et al.  Factor analysis of a sleep evaluation questionnaire , 1978, Psychological Medicine.

[23]  P Froom,et al.  The interactive effect of chronic exposure to noise and job complexity on changes in blood pressure and job satisfaction: a longitudinal study of industrial employees. , 2001, Journal of occupational health psychology.