The quality of sleep in the rhine-main region

Most of the overflights did not cause the sleepers to wake up. The NORAH team wanted to know more exactly whether some overflights disturbed sleep more than others. To do this they analyzed, among other things, the maximum sound level, i.e. the maximum loudness of each overflight, and the time. They found out – unsurprisingly – that louder overflights lead to more frequent wake-ups. However, the difference between the general background noises and the maximum sound level of the overflight also played a role: if the background noises were louder and the difference to the overflight noise therefore less, the participants woke up less frequently. The time also plays a role: towards the end of the night, when the sleep pressure decreased, the participants were more likely to wake up than at the start of the night.

Despite the different noise exposure in the years 2011 and 2012, the scientists were unable to establish any significant differences in various sleep characteristic values between the two years. In order to track down possible effects of nocturnal aviation noise, the NORAH team had measured, among other things, how long the participants lay awake at night and how long they needed to fall asleep. In none of the investigated sleep characteristic values (see table) were the scientists able to establish any statistically significant differences between the years and groups. Here an overview of the average values:

In 2013, the third year of the investigation, the scientists used a less complicated measurement method with just two electrodes: this registers how frequently the participants react physically to overflights – with accelerated heartbeat and body movements. Unlike the polysomnographic investigations of the previous years, the participants were able to attach the two necessary electrodes in the evening themselves. This meant that, with the same budget, the NORAH team could measure the sleep of considerably more persons than in 2011 and 2012.

The results show that the physical reactions to overflights increased substantially from 2011 to 2012: in 2011 the participants reacted to 10.7 percent of the overflights with no interference from other noise, in 2012 to 16.2 percent. In 2013 the proportion was 13 percent, i.e. it had fallen back again. The scientists cannot rule out that this may have to do with what is called a change effect. This is what noise impact researchers call it when people temporarily react more strongly to expected or actual noise changes, for example after the expansion of an airport.