Single and combined effects of air, road and rail traffic noise on sleep

INTRODUCTION: It is a well known fact that noise annoyance depends on the traffic mode. Much less is known about differences in physiological effects, especially on combined effects. Therefore, we investigated the effects of air (AI), road (RO) and rail (RA) traffic noise on sleep in the AIRORA study. METHODS: 72 subjects (40 ± 13 years, 32 male) were polysomnographically investigated during 11 consecutive nights in the laboratory. Electrophysiological signals included EEG, EOG, EMG, EKG, respiratory movements and finger pulse amplitude. Cortisol and noradrenalin were measured in nocturnal urine samples. Each traffic mode consisted of five noise categories (maximum SPL 45, 50, 55, 60 and 65 dBA) with 8 different noise events, i.e. 40 noise events in total. Therefore, between 40 and 120 noise events were realistically played back during single (AI, RO, RA, RORO), double (AIRO, AIRA, RORA) and triple (AIRORA) exposure nights. The design was complemented with a noise-free control night and carefully balanced. RESULTS: Annoyance due to aircraft noise was stronger compared to both rail and road traffic noise. However, according to multvariable random subject effect logistic regression models, awakening probability increased in the order AI, RO, RA (AI<RO, AI<RA, both p<0.0001; RO<RA, p=0.513). Cumulative effects in double and triple exposure nights were both lower (S1, SWS) and higher (Wake, REM) compared to expectations based on single exposure nights. Nocturnal traffic noise exposure had no influence on stress hormone excretion rates. CONCLUSIONS: Traffic modes differ in their noise effects on sleep. Field studies are needed to validate our results. INTRODUCTION It is a well known fact that noise annoyance depends on the traffic mode. Much less is known about differences in physiological effects, especially on combined effects. Therefore, the German Aerospace Center (DLR) investigated the effects of air (AI), road (RO) and rail (RA) traffic noise on sleep in the AIRORA study. STUDY DESIGN AND PROTOCOL Subjects were investigated for eleven consecutive nights. Night one served as adaptation. Nine different noise scenarios were played back during exposure nights two to ten. Night eleven served as a backup night, i.e. if signals of relevant electrodes were lost and sleep stage classification was impossible for one subject in nights two to ten, the respective noise scenario was presented in night eleven again.