Night noise guidelines for Europe - WHO/Europe - World Health ...

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SLEEP AND HEALTH
mal range. The hypothesis that an increased risk of cardiovascular diseases is connected
with stress concepts is generally accepted (Ekstedt, Åkerstedt and
Soderstrom, 2004; Ising and Kruppa, 2004). Stress reactions may lead to derangement
of normal neurovegetative and hormonal processes and influence vital body
functions. Cardiovascular parameters such as BP, cardiac function, serum cholesterol,
triglycerides, free fatty acids and haemostatic factors (fibrinogen) impede the
blood flow through increased viscosity and presumably blood sugar concentration
as well. Insulin resistance and diabetes mellitus, stress ulcers and immune system
deficiency are also frequent consequences of stress reaction. Disturbed sleep may
lead to immunosuppression and diminished protein synthesis (Horne, 1988).
As well as nonspecific effects of the stress response on the functioning of the immune
system, there is considerable evidence for a relation between sleep, especially SWS,
and the immune system (Brown, 1992). This evidence includes surges of certain
immune parameters and growth hormones at onset of SWS, correlation of non-REM
sleep, total sleep time and sleep efficiency with natural killer cell activity, and correlation
of SWS with recovery from infections. These data, taken together with information
on the effect of intermittent transportation noise on SWS during the first
sleep cycles and overnight, suggest that the immune response could also be impacted
directly by environmental noise during sleep (Carter, 1996).
2.2.3 SLEEP RESTRICTION, ENVIRONMENTAL STRESSORS
(NOISE) AND BEHAVIOURAL, MEDICAL AND SOCIAL
HEALTH CONSEQUENCES OF INSUFFICIENT SLEEP:
RISK OF MORBIDITY AND MORTALITY
Sleep restriction due to environmental stressors leads to primary sleep disorders, but
health is also influenced by the consequence of stress response to noise mediated by
the HPA axis and/or by restriction of specific sleep stages (see above).
Sleep restriction leads, in approximately 40% of affected subjects, to daytime sleepiness
that interferes with work and social functioning. Excessive daytime sleepiness is thus a
major public health problem, as it interferes with daily activities, with consequences
including cognitive problems, motor vehicle accidents (especially at night), poor job performance
and reduced productivity (Lavie, Pillar and Malhotra, 2002). In the last
decade, experimentally based data have been collected on chronic restriction of sleep (by
1–4 hours a night), accumulating daytime sleepiness and cognitive impairment. Most
individuals develop cognitive deficits from chronic sleep debt after only a few nights of
reduced sleep quality or quantity. New evidence suggests additional important healthrelated
consequences of sleep debt related to common viral illnesses, diabetes, obesity,
heart disease, depression and other age-related chronic disorders.
The effects and consequences of sleep deprivation are summarized in Table 2.4
(Lavie, Pillar and Malhotra, 2002).
The relationship between sleep quantity and quality and estimates of morbidity and mortality
remains controversial. Epidemiological data (NCSDR, 2003) suggest that habitually short
sleep (less than 6 hours sleep per night) is associated with increased mortality. Epidemiological
studies in recent years elucidated, however, that too much sleep is a problem as well. Kripke
et al. (2002) evaluated a questionnaire study of 1.1 million men and women aged 30–102
years and found the lowest mortality risk between respondents sleeping 7 hours per night.
NIGHT NOISE GUIDELINES FOR EUROPE