PROCEEDINGS of the23rd International Congress on Acoustics
9 to 13 September 2019 in Aachen, Germany

Effects of nocturnal aircraft noise on objective and subjective sleep
quality in primary school children
Susanne BARTELS1; Julia QUEHL1; Daniel AESCHBACH1
1

Institute of Aerospace Medicine, German Aerospace Center, Germany

EXTENDED ABSTRACT
Background: Disturbances of sleep represent adverse effects of nocturnal aircraft noise exposure.
These disturbances can include awakening reactions, changes in the sleep depth and sleep continuity.
Restorative sleep is vital for physiological and cognitive development of children. Children are lesscapable to estimate threats from environmental stressors and to use adequate coping strategies (1, 2).
Moreover, they are in a sensitive developmental period (2). Children who are exposed to hightransportation noise levels from an early age may have higher risks for cardiovascular problems intheir adult life (3). Furthermore, children generally sleep longer than adults and during shoulder timesof the night when (air) traffic density is high. They are therefore considered vulnerable to the negative
consequences of transportation noise (4, 5). However, little is known about childhood sleep exposed totransportation noise. An investigation seemed particularly necessary due to the diff erences of sleep
architecture between children and adults. The present study aimed at closing the research gap
regarding the acute effects of nocturnal aircraft noise on sleep of primary school children.
Methods: We investigated the effect of aircraft noise on sleep in a field study in 51 children aged
8 to 10 years. All participants resided near Cologne/Bonn Airport representing an important German
hub with a 24-h operating scheme. Aircraft noise was the dominant noise source at all measurementsites. Participants were screened for hearing impairments and age-adequate normal bedtimes. We
excluded individuals with intrinsic sleep disorders, medical conditions, or medication use which might
have interfered with the study protocol or the interpretations of the results of the study. Sleep wasmeasured polysomnographically (via EEG, EMG, EOG, ECG, and pulse oximetry) during four
consecutive nights. The first night served as adaptation to the protocol and the measurement devices.
Sleep stage classification was based on the criteria of Rechtschaffen and Kales ( 6). In addition,subjects rated their sleep quality and current fatigue each morning using a verbal five -point scale withgraphical anchors. During all nights, aircraft and ambient sounds and sound pressure levels wererecorded continuously with a one class-1 sound level meter next to the children’s ears. Aircraft noise
exposure was quantified by the number of aircraft noise events above 30 dB(A) per night. We
considered only aircraft noise events which did not overlap with sounds from other sources.
144 nights with valid data regarding acoustic as well as objective and subjective sleep
measurements were available for statistical analyses. For the prediction of objective and subjective
sleep quality from aircraft noise exposure, we applied mixed models with random intercept and thenumber of noise events as dichotomous factor (median split at 37.5 events). The following variables
were analyzed: a) sleep onset latency to stage 2 (in min), b) sleep efficiency (proportion of sleep time
during time in bed, in %), c) proportion of slow wave sleep (S3 and S4) per total sleep time (in %), d)
proportion of REM sleep per total sleep time (in %), e) wake duration during sleep period time (in %),f) self-rated sleep quality, g) self-rated fatigue in the morning. In addition, we applied linear mixed
models with random intercept to analyze the relationship between objective and subjective sleep
measurements.
Results: Aircraft noise exposure affected the macrostructure of sleep. A higher number of noise
events during the night was associated with a reduction of the proportion of slow wave sleep in total
seep time by 2.6 % (p = .034) and an increase of waking during sleep period time by 1.2 % (p = .023).
13664

susanne.bartels@dlr.deSleep onset time tended to be longer by 3.3 min in nights with higher noise exposure (p = .062). Sleep
efficiency was not significantly reduced in higher exposed nights (p = .112), neither was the proportionof REM sleep per total sleep time (p = .834).
Subjective sleep quality and self-rated fatigue in the morning did not differ between nights withhigher and lower aircraft noise exposure (p = .694, and p = .269, respectively). Except for theproportion of wakefulness per sleep period time (p < .001), the above mentioned objective sleep
measures were not significantly related to subjective sleep quality. On a trend level, subjective sleep
quality decreased with longer sleep onset latencies (p = .055) and lower sleep efficiencies (p = .074).
Self-rated fatigue increased with longer wake durations during the sleep period time (p =.036). There
was no significant or trend-level relation between any of the other objective sleep parameters andsubjective fatigue.
Discussion and conclusion: Our results showed an impact of aircraft noise exposure on the sleep
architecture of primary school children. Significant effects were found for the proportion of slow wave
sleep per total sleep time as well as wake duration during the sleep period. With exception for REM
sleep, which was not affected by aircraft noise exposure, these findings are roughly in line with resultsfrom prior studies with adult participants. To evaluate the effects of aircraft noise on sleep architecturein the context of the existing body of knowledge, a comparison is sometimes drawn to the impact ofintrinsic sleep and breathing disorders on sleep structure. For adults, the impact of aircraft noise on
sleep is considered subtle compared to the more severe fragmentation of sleep and reduction of slow
wave sleep due to, for instance, the obstructive sleep apnea syndrome (OSAS, 7). However, forprimary school children, effects of OSAS on sleep architecture have been shown to be much smaller. In
a very recent study (8), comparing children with OSAS to a healthy control group, the magnitude of theloss in slow wave sleep per total sleep time (3.3 %) and sleep efficiency (1.0 %) were similar to ourresults. These small but recurring disturbances of slow wave sleep have been postulated as a risk formetabolic, cognitive, and cardiovascular diseases (8, 9). Therefore, the consequences of chronic
aircraft noise-induced loss of slow wave sleep need further investigation.
It is important to stress that the current findings and conclusions apply to a continuous nighttime
noise scenario as is the case at Cologne/Bonn Airport, but they should not be generalized to all airports.
Compared to other national and international airports with a night flight ban between e.g. 23:00 h and
05:00 h, the number of flights during the shoulder times of the night is moderate at Cologne/Bonnairport. It would be very important to know the consequences of a night curfew scenario. Thesescenarios are characterized by dense air traffic during the hours before 23:00 h, overlapping with theearly part of primary school children’s sleep, and by the absence of air traffic during the middle part oftheir sleep episode.
As found and discussed previously (10), self-assessments of sleep do not necessarily correlate with
objective sleep measures in adults. Present results suggest that this holds true for children a well. With
exception for wakefulness during the sleep period time, the objectively measured deterioration ofsleep architecture was not mirrored by self-rated sleep quality and fatigue in the morning. Our findings
underline the importance of objective measures for identifying noise-induced changes in sleep.
Keywords: aircraft noise, children, sleep, field-study

REFERENCES
1. Bruni L, Novelli R, Ferri, R Sleep disturbance in children by noise. In: Nriagu JO, editor. Encyclopediaof Environmental Health. Amsterdam, the Netherlands: Elsevier Science and Technology; 2011. p88-94.
2. van Kamp I, Davies H. Noise and health in vulnerable groups: a review. Noise & Health, 2013;15:153–
159.
3. van Kempen E, Casas M, Pershagen G, Foraster M. WHO Environmental Noise Guidelines for theEuropean Region: A Systematic Review on Environmental Noise and Cardiovascular and Metabolic
Effects: A Summary. International Journal of Environmental Research and Public Health.
2018;15(379):1-59.

3665

4. Basner M, McGuire S. WHO Environmental Noise Guidelines for the European Region: A Systematic
Review on Environmental Noise and Effects on Sleep. International Journal of Environmental
Research and Public Health. 2018;15(519):1-45.
5. Stansfeld SA, Clark C. Health effects of noise exposure in children. Current Environmental HealthReports. 2015, DOI 10.1007/s40572-015-0044-1.
6. Rechtschaffen A, Kales A, Berger RJ, Dement WC, Jacobsen A & Johnson LC. A manual ofstandardized terminology, techniques and scoring system for sleep stages of human subjects.
Washington, D.C, USA: Public Health Service, U.S. Government, Printing Office.1968.
7. Basner M, Griefahn B, Berg M. Aircraft noise effects on sleep: Mechanisms, mitigation and researchneeds. Noise Health, 2010;12: 95-109.
8. Durdik P, Sujanska A, Suroviakova S, Evangelisti M, Banovcin P, Villa MP. Sleep architecture inchildren with common phenotype of obstructive sleep apnea. Journal of Clinical Sleep Medicine. 2018;
14(1): 9-14.
9. Wiater A Paditz E, Schlüter B, Scholle S, Niewerth HJ, Schäfer T, Erler T, Schachinger H. Obstruktives
Schlafapnoesyndrom im Kindesalter. Deutsches Ärzteblatt. 2002;99 (49), A-3324-A3330.
10. Basner M, Brink M, Elmenhorst E-M. Critical appraisal of methods for the assessment of noise effects
on sleep. Noise & Health.2013;14(61):321-329.

3666