The effects of noise disruption on sleep disturbance

INTERVENTION: These experiments are specifically designed to establish wind farm versus traffic noise effects on sleep efficiency (macro‐structure), and micro‐arousal responses to each noise type at equivalent A‐weighted Sound Pressure Levels (SPL). Twenty participants from each of the 4 experimental groups will be asked to attend the laboratory for 7 consecutive night sleep studies (4 experimental nights, each with an intervening recovery night). Experimental nights will consist of; prolonged wind farm and traffic noise exposures (WF and T nights), a noise fragmentation night (i.e., randomised and counterbalanced WFN and TN at various SPL, along with silent control exposures), and a control night in random order. Participants will be instrumented for sleep and physiological measures prior to going to bed at their habitual bedtime each night and instructed that they may or may not notice any noises on any of the nights. Experimental noise exposures will only commence once polysomnographically defined stable (>2 min) stage 2 or deeper sleep is already established (or re‐established) to avoid noise interference with sleep onset, which we do not believe can be adequately blinded in full night noise exposure experiments. WFN and TN arousal thresholds in deep and stage 2 sleep will be measured on each experimental night using an established brief noise‐escalation protocol. WFN and TN nights will be constructed to approximate worst case noise exposure nights (from existing recordings) using 3‐min periods of pre‐recorded noises with minimal time‐variability, randomised into a sequence containing both no noise (control exposures) and A‐weighted SPLs up to original recording maxima in 3‐6 dBA increments. We will use fade‐in over the first 30‐sec and A‐weight SPL matching between noise types and include noises both unfiltered and filtered to exclude low frequencies <160 Hz and infrasound <20 Hz. The primary outcome is sleep efficiency (sleep time as a % of each 5 min exposure), whic CONDITION: Low frequency noise effects on sleep; ; Low frequency noise effects on sleep Public Health ‐ Other public health PRIMARY OUTCOME: Quantitative micro‐structural changes of EEG arousal including frequent micro‐arousals (3‐15 sec EEG changes to faster frequencies) fragmenting sleep.[During each of the seven overnight laboratory‐based sleep studies.] The primary outcome will be EEG measures of sleep quality including sleep efficiency, calculated as total sleep time expressed as a percentage of time available for sleep under each noise exposure condition.[During each of the seven overnight laboratory‐based sleep studies.] INCLUSION CRITERIA: • Age > 17 years; and • Freely given informed consent; and • One of the following: ‐ Live < 10 km from a wind turbine; or ‐ Live in a quiet rural area; or ‐ Live adjacent to a busy road traffic corridor SECONDARY OUTCOME: Cardiovascular activation associated with isolated k‐complexes and full awakenings assessed using Electroencephalography.[During each of the seven‐overnight laboratory‐based sleep studies.] Cardiovascular activation responses assessed using pulse wave amplitude attenuation responses.[During each of the seven overnight laboratory‐based sleep studies.] Cortisol responses assessed using salivary cortisol assays (i.e., salivettes).[During each of the seven‐overnight laboratory‐based sleep studies.] Daytime alertness assessed using reaction time (Psychomotor vigilance task; PVT).[In the morning after each of the seven‐overnight laboratory‐based sleep studies.] Daytime sleepiness assessed via the Karolinska Drowsiness Test and Karolinska Sleepiness Scale[In the morning after each of the seven‐overnight laboratory‐based sleep studies.] Sleep macro‐structure fragmentation assessed using quantitative spectral analyses via Electroencephalography.[During each of the seven overnight laboratory‐based sleep studies.]