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

EFFECTS ON SLEEP
53
n max (/1000)
20
15
10
5
SEL0
L night = 46
L night = 51
L night = 56
Fig. 3.3
Maximum number of
noise-induced motility for
three values of L night .
Converted from inside
relation with [3]
on page 10
0
61 66 71 76 81 86 91 96 101
SEL, outside
Source: Miedema,
Passchier-Vermeer and Vos,
2003.
3.1.9 INDIVIDUAL SENSITIVITY
Sensitivity to noise may vary greatly from one individual to another. Primary self-evaluation
of sensitivity to noise has been used as a factor to evaluate highly sensitive and
non-sensitive groups and to compare their reactions to noise exposure during daytime
and night-time (Di Nisi et al., 1990). In this study, self-declared highly sensitive individuals
had a higher cardiovascular response rate to noise than non-sensitive people during
their waking exposure, while there was no difference in sensitivity to noise between
these two groups during their night-time exposure while they were asleep.
The physiological sensitivity to noise depends also on the age of the sleeper. Thus, while
EEG modifications and awakening thresholds are, on average, 10 dB(A) higher in children
than in adults, their cardiovascular sensitivity to noise is similar, if not higher, than
the older group (Muzet and Ehrhart, 1980; see also Appendix 4). Elderly people complain
much more than younger adults about environmental noise. However, their spontaneous
awakenings occurring during night sleep are also much more numerous.
Therefore, it is difficult to conclude if elderly people are more sensitive to noise or if they
hear noise because they are often awake during the night. This natural fragmentation of
their night sleep tends also to lengthen their return to the sleeping state and this accounts
for a significant part of their subjective complaints.
Differences in sensitivity to noise have been found between the sexes. Thus, young men
seem to complain more about noise-disturbed sleep than young females (Muzet et al.,
1973). However, this difference seems to reverse for populations over 30 years of age
and then females (often mothers) appear to be more sensitive to noise than males
(Lukas, 1972b).
3.1.10 USE OF INSTANTANEOUS EFFECTS IN PREDICTIONS
OVER A LONGER TIME PERIOD
It is tempting to use the relations between single exposures and measured effects in longterm
predictions. Although this is perhaps possible, a word of caution is appropriate.
In general, the reactions are calculated by looking at a certain time frame around an
exposure, usually in the order of a few minutes. The second limitation is that order
and follow-up effects are neglected. Time and order effects of identical events on
NIGHT NOISE GUIDELINES FOR EUROPE