Re: Wind turbine noise
An original research proposal: Effects of noise on sleep and their potential repercussion on cardiac patients in hospital settings
Dr.Tanu Pramanik BSc. MA (Sociology) DSc (Clin.Psychology) Lecturer & Research Supervisor,Allianze University College of Medical Sciences, 13200-Penang, Malaysia.
The author of the current editorial “Wind turbine noises” deserves sincere applause for his firm statement- “we are firm in our assertion that the evidence for harm at distances and noise levels permitted under current regulations in most jurisdictions is such that regulators should take notice and initiate research (1).
Many clinical psychologists and sleep medicine experts consider that normal sleep should be regarded as one of the basic human rights, because chronic sleep disturbance due to any kind of noise pollution is a well-documented cause of several psychosomatic disorders. Sleep patterns are particularly susceptible to noise for a number of reasons. First, our brains are able to process incoming acoustic stimuli even while asleep. Second, the noise levels that effect sleep are much lower than those required to impair hearing.
The World Health Organization guidelines say that for a good sleep, sound level should not exceed 30 dB(A) for continuous background noise, and 45 dB(A) for individual noise events.(2)
During sleep, the sound levels that cause noise-induced stress reactions are much lower than in the active phase. Furthermore, a shift worker in a wind turbine firm or in an airport may sleep during relatively high noise levels but still shows autonomic responses, such as increased heart rate.
The effect of noise on sleep, however, not only depends on the acoustical parameters of noise but also on the individual as there is large variance in the experience of a person with a particular noise. Personal characteristics such as personality traits, diurnal type, age and self-estimated sensitivity to noise are important individual factors.(3)
In one study, rats were exposed to environmental noise for 9 days. Results showed that this chronic exposure continually restricted the amount of slow wave sleep (SWS).(4)
These autonomic responses to noise during sleep can be obtained for much lower peak noise intensities as during wake states. These effects, mainly involving increased heart rate and vasoconstriction, have been found to habituate over successive noise-exposed nights as opposed to long exposure times. This could indicate an effect on cardiovascular response over the long term exposure.(5)
Current understanding, however, indicates that sleep has important physiologic restorative functions. An improved understanding of physiologic activities during normal sleep has shed light on the important cardiovascular, neuroendocrine, immunologic and behavioral/cognitive changes associated with disturbed sleep.
Chronic exposure to an environmental noise (EN) induces sleep disturbances but is not fully known what impact these disturbances have on humans.
However, we appreciate the author’s comment that “there is not a single published study showing lack of adverse effects of noise on sleep and health”.
Therefore, we designed current research proposal with an objective to study noise induced repercussions on cardiac patients in a hospital setting. During our study, we will use EEG, EKG, polysomnogram and other monitoring systems for the patients selected under stringent criteria set by the clinical research committee and University ethical committee.
During sleep, heart rate is related to changes in the parasympathetic-sympathetic balance with an increase in sympathetic tone associated with activation and with electroencephalogram (EEG) arousal. Catecholamine levels and sympathetic activity decrease during sleep.
So, as one might assume that decreased sleep is associated with increased sympathetic activity and as a result increased blood pressure and heart rate. This association has been observed not only with sleep deprivation but also with regard to sleep disruption. Brief awakenings from sleep for only a few seconds are associated with temporary elevation in blood pressure and heart rate that results from an autonomic reflex.(6)
One study reports heart rate acceleration with auditory stimulation during sleep even when no EEG arousal was observed. These findings thus question whether activation of the autonomic nervous system night after night without visual EEG arousal or alpha-alpha-beta EEG changes of shorter duration could have long-term detrimental effects on the cardiovascular system. By contrast, the results suggest that brain stem activation can lead to autonomic nervous system response without creating objective consequences on specific tests of psychomotor vigilance during the following day.(7)
Studies report that total and partial sleep deprivation cause changes in mood and cognition such as increased sleepiness, fatigue, irritability and an overall decrease in concentration.(8) Other effects of sleep deprivation include longer reaction times, poor short-term memory, reduced motivation, distractibility and poor performance.(9)
Environmental factors, such as work pressure, lifestyle choices and noise are major causes of sleep disturbance. Because sleep is a crucial physiological recuperative state, sleep disorders are known cause of many negative health effects. Such effects include, but are not limited to, cardiovascular problems, neuroendocrine abnormalities and changes in cognition, mood and memory. The causal relationships between noise exposure, effects on sleep, and contribution to health disturbances, both behavioral and physical, are not firmly established yet. Our research may reveal adequate experimental data to substantiate general opinion about noise induced repercussions on human health.
Last but not the least, wind turbine noise may amount to what the common law regards as a nuisance, and entitle a person to take proceedings in the courts. If the court is satisfied that the noise complained of constitutes a nuisance, honorable court can order the person responsible to stop or remove the nuisance. It can also order compensation to be paid. Statute law also deals with nuisances. The Health Act 1958 (Vic) ("Health Act") expressly provides that a nuisance includes any noise which is or is liable to be dangerous to health or noxious, annoying or injurious to personal comfort.(10)
1. Christopher D Hanning, and Alun Evans, Editorial:Wind turbine noise BMJ 2012; 344 doi: 10.1136/bmj.e1527 (Published 8 March 2012) : BMJ 2012;344:e1527
2. Berglund B, Lindvall T, Schwela DH. Guidelines for Community Noise. World Health Organization 1999. Available from: http://www.who.int/docstore/peh/noise/guidelines2.html . [Accessed on 2010 March 28].
3. Muzet A, Weber LD, Di Nisi J, Ehrhart J. Comparison of cardiovascular reactivity to noise during waking and sleep. National Center for Scientific Research Center for Bioclimatic studies. Convention No 82243, 1985.
4. Ohrstrom E, Bjorkman M. Effects of noise-disturbed sleep- a laboratory study on habituation and subjective noise sensitivity. J Sound Vib 1988;122:277-90.
5. Muzet A, Ehrhart J, Eschenlauer R, Lienhard JP. Habituation and age differences of cardiovascular responses to noise during sleep. In Sleep 1980;212-5.
6. Sforza E, Chapotot F, Lavoie S, Roche F, Pigeau R, Buguet A. Heart rate activation during spontaneous arousals from sleep: Effect of sleep deprivation. Clin Neurophysiol 2004;115:2442-51.
7. Guilleminault C, Abad VC, Philip P, Stoohs R. The effect of CNS activation versus EEG arousal during sleep on heart rate response and daytime tests. Clin Neurophysiol 2006;117:731-9.
8. Dinges DF, Pack F, Williams K, Gillen KA, Powell JW, Ott GE, et al. Cumulative sleepiness, mood disturbance, and psychomotor vigilance performance decrements during a week of sleep restricted to 4-5h per night. Sleep 1997;20:267-77.
9. Bonnet MH, Arand DL. Clinical effects of sleep fragmentation versus sleep deprivation. Sleep Med Rev 2003;7:297-310
Competing interests: The continuous moral support of Prof. Dato 'Dr. Zainuddin Md Wazir, President, Allianze University College of Medical Sciences, Malaysia, is cordially acknowledged.