Effects of nocturnal air and rail traffic noise on sleep

Undisturbed and sufficiently long sleep is a prerequisite for a healthy life as well as for the prevention of fatigue-induced accidents. Especially the increasing air and freight rail traffic is more and more shifted to shoulder and night-time hours due to missing capacity and infrastructure during daytime. Thus, the sleep of residents near airports or railway tracks is increasingly affected by traffic noise. Only very few main airports, such as Frankfurt (Germany), implemented a night flight ban in order to countervail this trend. Since 1999 the Institute of Aerospace Medicine of the German Aerospace Center (DLR) has investigated these night time noise effects in several field studies in which the sound pressure levels L AS and L AF and sound files were continuously measured with class one sound level meters at the sleeper's ear. Sleep structure was recorded with polysomnography (simultaneous measurement of brain waves, eye movements, and muscle tone), the gold-standard to quantify sleep objectively. The results on sleep quality and additional awakening reactions due to traffic noise from former studies performed at Cologne/Bonn airport (high night time traffic) and a busy railway track in the Rhine valley (high night time freight traffic) are compared with the results of the recently completed NORAH (Noise-Related Annoyance, Cognition, and Health) study at Frankfurt airport. In the latter study data were collected both before as well as after the implementation of a ban of night flights between 11 p.m. and 5 a.m.. Sound exposure distributions, average sound levels and sound level rise time distributions at the sleepers' ear are presented for all three studies

A comparison of the effects of night time air traffic noise on sleep at Cologne/Bonn and Frankfurt Airport after the night flight ban

In the STRAIN study (2001/2002) the German Aerospace Center (DLR) measured the sleep of 64 residents (19-61 years) around Cologne/Bonn airport for 9 consecutive nights each with polysomnography. Cologne/Bonn airport has no night time restrictions for chapter 3 airplanes and is one of the busiest airports in Germany during the night. Frankfurt is the airport with the highest traffic volume in Germany. A night flight ban (11 p.m.-5 a.m.) was implemented in October 2011. Traffic density during shoulder hours is high. DLR examined 83 Frankfurt airport residents (18-77 years) with polysomnography as part of the NORAH study in 2012. In both studies sound pressure level (SPL) and noise events were recorded with microphones near the sleeper's ear. Participants filled out questionnaires each morning. The analysis shows that aircraft noise associated awakening probabilities were 3.8-7.5% higher for maximum indoor levels from 30-70 dB(A) at Cologne/Bonn Airport whereas night time aircraft noise annoyance was higher in Frankfurt. The results of both studies are compared, and limitations of the comparisons are discussed

Cross-country comparison of aircraft noise-induced sleep disturbance

To inform policy, exposure-response relationships for aircraft noise-induced sleep disturbance are needed. Due to different nighttime airport operational patterns it has been unknown whether results from individual studies can be applied to other airports. In addition, there may be inter-cultural differences that affect an individual's sensitivity to awakening. To examine whether there are crosscountry differences in aircraft noise-induced awakenings, results from 3 studies that obtained objective sleep and noise measurements were compared. Two of the studies were conducted in Germany and include the STRAIN study conducted near Cologne/Bonn airport (N=64) and data from three years of the NORAH study conducted near Frankfurt airport (year 1 N=49; year 2 N=83; year 3 N=187). The third study was conducted in the United States near Philadelphia International airport (N=37). Awakenings were identified based on ECG and actigraphy measurements using an automatic algorithm, enabling consistency in scoring across the three studies. Models relating awakenings to the indoor maximum noise level of single aircraft events were derived. Similarities and differences in the regressions of the 3 studies are discussed

Reestablishment of individual sleep structure during a single 14‐h recovery sleep episode after 58 h of wakefulness

Sleep structure is highly stable within individuals but different between individuals. The present study investigated robustness of the individual sleep structure to extended total sleep deprivation. Seventeen healthy men spent a baseline night (23:00-07:00 hours), 58 h of sleep deprivation and a 14-h recovery night (17:00-07:00 hours) in the laboratory. Intraclass correlation coefficients showed that the agreement between baseline and recovery with respect to the proportion of the different sleep stages increased as a function of recovery sleep duration. High values were reached for most of the sleep stages at the end of 14 h of recovery sleep (intraclass correlation coefficients between 0.38 and 0.76). If sleep duration of the recovery night is extended to 14 h, sleep stage distribution resembles that of a baseline night underlining the robustness of the individual sleep structure

Event-related analysis of awakenings due to road traffic noise at night –a polysomnographic field study

Objectives/Introduction: Nocturnal traffic noise causes sleep disturbances in residents. Thus, knowledge about noise effects is important to help protect residents’ sleep and maintain health, well-being, and performance. In recent years, DLR has established exposure-response curves regarding the effects of aircraft and railway noise on the awakening probability of residents. However, such a curve has not yet been established for road traffic noise. Methods: We conducted a field study in residential areas where road traffic was the dominant noise source and noises were attributable to separate events. Forty healthy participants (mean age = 29.1, SD = 11.7; 26 females) that were free of sleep disorders were polysomnographically examined for five consecutive nights. Acoustic measurements were undertaken at the sleepers’ ear. The synchronous collection of electrophysiological and acoustic data allowed for an event-related analysis of noise events and associated awakenings. Results: The present analysis included 152 nocturnal recordings with a total of 11265 road traffic noise events within the participants’ sleep period. Participants were exposed to a median of 107 road traffic noise events per night. A random effects logistic regression model, including acoustic, sleep-related and participant-related (e.g. age) variables, revealed a significant increase in the awakening probability with increasing maximum sound pressure level of a noise event (p < 0.001). When holding all confounding variables constant at their respective sample median, the awakening probability per single noise event ranged from 0.5 % at 24.2 dB(A) to 3.8 % at 70 dB(A) maximum sound pressure level. Assuming an exposure of 107 noise events per night with maximum sound pressure level of 39.4 dB(A) (median) the model estimates on average one noise-induced awakening per night. Conclusions: The present study is of high ecological validity and provides for the first time an exposure-response curve regarding the effect of separate road traffic noise events on the awakening probability. Our study focussed on residential areas with moderate traffic density at night. Further investigations of urban areas with dense traffic are still needed, which, however, will require a novel methodological approach as an event-related analysis is no longer feasible. The ultimate goal will be to establish physiologically based noise protection measures

Short-term annoyance from nocturnal aircraft noise exposure: results of the NORAH and STRAIN sleep studies

Purpose The German Aerospace Center (DLR) investigated in the NORAH sleep study the association between a distinct change in nocturnal aircraft noise exposure due to the introduction of a night curfew (11:00 pm-5:00 am) at Frankfurt Airport and short-term annoyance reactions of residents in the surrounding community. Exposure-response curves were calculated by using random effects logistic regression to evaluate the aircraft noise-related parameters (1) number of overflights and (2) energy equivalent noise level LASeq for the prediction of short-term annoyance. Data of the NORAH sleep study were compared with the STRAIN sleep study which was conducted by DLR near Cologne-Bonn Airport in 2001/2002 (N=64), representing a steady-state/low-rate change. Methods The NORAH sleep study was based on questionnaire surveys with 187 residents living in the vicinity of Frankfurt Airport. Noise-induced short–term annoyance and related non-acoustical variables were assessed. Nocturnal aircraft noise exposure was measured inside the residents` home. Results A statistically significant rise in the portion of annoyed residents with increasing number of overflights was found. Similarly, the portion of annoyed subjects increased with rising LASeq. Importance of the frequency of fly-overs for the prediction of annoyance reactions was emphasized. The annoyance probability was significantly higher in the NORAH than in the STRAIN sleep study. Conclusions Results confirm the importance of both acoustical parameters for the prediction of short-term annoyance due to nocturnal aircraft noise. Quantitative annoyance models that were derived at steady-state/low-rate change airports cannot be directly applied to airports that underwent a distinct change in operational and noise exposure patterns