A globally unique programme of field research has been designed to address the effect of aircraft noise on children's sleep. Researchers at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) will be conducting a study on the sleep patterns of a total of 50 children living in the vicinity of Cologne/Bonn Airport until 2018. The study is expected to provide insight into how nocturnal aircraft noise affects the sleep, cognitive ability and psychological well-being of children.
Closing knowledge gaps
Research into the effects of noise on the human body has been carried out in Germany for 40 years. The influence of nocturnal traffic noise on sleep has also been investigated in numerous studies. Nevertheless, many questions remain unanswered. For example, the 'vulnerable' group that includes children has not yet been studied. But researchers suspect that, in this group in particular, noise has negative effects on sleep – and hence on the ability to recover from its effects.
Good, sound sleep is extremely important for the physical and psychological development of children. However, whether and exactly how aircraft noise affects the sleep of children is still largely unknown. Data acquired from past research is somewhat contradictory. Specifically, there is still a lack of understanding of how aircraft noise affects sleep patterns 'in the field' – that is, at the test subjects' homes rather than in a laboratory.
For this reason, experts at the DLR Institute of Aerospace Medicine are planning to investigate how children's sleep is affected by aircraft noise; how long it takes children to fall asleep in the evening because of aircraft noise; how often they wake up in the night because of this; and how often and when a shift from a deeper to a lighter sleep state takes place.
To record their sleep data, the children will be studied polysomnographically at home for four consecutive nights. "This means that a variety of electro-physiological bodily functions are recorded throughout the night," explains Julia Quehl from the Institute’s Department of Flight Physiology. "To do this, the children will wear child-appropriate electrodes on their heads and upper bodies every night." These will provide the researchers with data that will help them measure levels of brain activity, to determine the various sleep states and waking reactions. In addition, all noise reaching the sleeping children's ears will be recorded in their rooms throughout the night. In this way, the researchers will be able to combine measurements of sleep patterns (for example, changes in the state of sleep or waking reactions) with individual noise events such as a take-off or landing at night.
Subjective noise perception
In addition to this objective data, the researchers will use child-appropriate questionnaires conducted each morning to provide subjective data on how the children have personally experienced their sleep and aircraft noise during the night. This, in turn, will reveal the extent to which the children have been disturbed by the noise – from their own perspective. In addition, their cognitive abilities will be measured each morning in a psychological reaction time test on a laptop. "We will carry out the test with the children prior to the study," explains Quehl. "It will allow us to know their individual performance level in the test. Using the test scores during the study, we will be able to determine whether any noise-related impact on performance is detectable."
Strict criteria when selecting test subjects
Only boys and girls between the ages of 8 and 10, in good health and with normal hearing, will take part in the study, which will be carried out as part of the MIDAS project (Maßnahmen und Instrumente des Aktiven Schallschutzes bei Fluglärm – Procedures and Instruments for Active Protection relating to Aircraft Noise). The reason for this is that, in order to achieve scientifically credible results, all of the children must have a similar sleep structure. This is because, with age, the amount of time that children spend in the various phases of sleep and the total amount of sleep change. Children with hearing difficulties, chronic illnesses or those that need to take medication cannot take part; this could have an impact on the recording of the sleep data.
Potential test subjects must live in the vicinity of Cologne/Bonn Airport and their district must be affected by aircraft noise at night. In addition, the children must not be exposed to other sources of noise, such as road traffic, trains or industry. Only the effects of nocturnal noise from aircraft are intended to be studied. Furthermore, the test subjects will be selected in accordance with acoustic criteria. Acoustic test measurements will be carried out on site to ensure that individual aircraft noise events are not being masked by background noise. This would make a huge difference in the comparison of the acoustic data with the sleep data. The test subjects will be selected using questionnaires completed by the children and their parents, as well as by the results of a hearing test.
Collating the results
Using the collected acoustic data, the electro-physiological data on sleep patterns and the subjective data on sensitivity to disturbance, the researchers will generate exposure-response curves. These will indicate how the probability of a specific noise reaction (for example, a change of sleep state) changes as a function of noise. "Until now, exposure-response curves have only been produced for adults in relation to nocturnal aircraft noise and sleep, not for children," says Susanne Bartels, also from the Department of Flight Physiology. "We will be able to calculate such curves for children as well as a result of our study and then compare them with those of adults. Only then will we be able to say whether the effects of aircraft noise on the sleep patterns of adults and children are different."
The study will take place between June and October of 2016 and 2017. More information, including the precise conditions for participation and the opportunity to apply to take part in the study can be found Institute of Aerospace Medicine.