A field survey of windfarm and traffic noise effects on sleep (In-Home Study)

Participation in the field measurement protocol will involve two consecutive night recordings. Two nights will help assess repeatability, increase study power and maximise acoustic and sleep recording opportunity. Research personnel including one trained sleep technician and one sound technician, will visit each participant’s home to setup acoustic recording and sleep monitoring equipment (including Electroencephalogram [EEG] and Electrocardiography [ECG]) using already established equipment and methods. As much as is possible, experiments will be scheduled around anticipated worst case traffic/wind farm noise nights based on schedules and weather reports. Participants' hearing will be tested prior to night 1 of the protocol using an audiometer. To ensure data quality, each evening the research personnel will remain at the participants' home until participants' bedtime and return in the mornings to collect the overnight data. After each night, participants will be asked to rate overall sleep quality and noise relative to their usual sleep. They will collect 5 serial saliva samples immediately upon awakening, over the next 60 min and 12 hours after waking for salivary cortisol (cortisol awakening response) measurements. Hair follicles will also be collected to measure markers of long-term stress. Sleep studies will be scored into sleep stages. They will also be scored for respiratory and arousal events using international standards independent of the acoustic data to assess overall sleep quality (sleep efficiency, wake time after sleep onset, and frequency of arousals). In addition, cardiovascular activation responses, including tachy-bradycardias, pulse wave velocity and pulse wave amplitude attenuation responses will also be examined. All discernible sensory-related activation responses including cardiovascular activation associated with isolated k-complexes, 3-15 sec arousals and full awakenings will be selected for further analysis of event rates per hour of sleep, and noise characteristics preceding each activation event type. Noise will be assessed based on spectral content, overall mean and peak unweighted, A-weighted and G-weighted SPLs and random/periodic variability with time. Full-night quantitative EEG and ECG spectral analyses will also be conducted.