Metabolic and Cognitive Consequences of Noise-induced Sleep Disturbance

Study Overview
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Brief Summary
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This study will investigate the biological mechanisms linking sleep disruption by noise and the development of disease. In a laboratory sleep study, we will play traffic sounds of different types (road, rail and air) and noise levels during the night. We will also have nights with sound from so-called white noise machines. These generate a low-level and continuous noise that may improve sleep by masking the traffic noises that would otherwise disturb sleep. We will also measure objective sleep quality and quantity, cognitive performance across multiple domains, self-reported sleep and wellbeing outcomes, and blood samples. Blood samples will be analysed to identify metabolic changes in different nights. Identifying biomarkers that are impacted by sleep fragmentation will establish the currently unclear pathways by which chronic noise exposure at night can lead to the development of diseases in the long term, especially cardiometabolic disorders.

Detailed Description
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The experimental sleep study has the overarching goal of deepening our understanding of experimentally-induced disruption of sleep and changes in metabolic and cognitive function, and to determine the efficacy of a potential non-pharmacological intervention to promote sleep. To this end, the study will address the following independent aims: Aim 1: Determine associations between novel physiologic markers of sleep and metabolic and cognitive function. We will measure the sleep of healthy volunteers using novel and classical indictors of sleep architecture. Each morning we will obtain blood samples for metabolomics analysis and administer a neurocognitive test battery. Aim 2: Determine the biological and neurobehavioral consequences of noise-disrupted sleep. We will compare effects on sleep, metabolomics and cognitive function between quiet nights and nights with traffic noise. Aim 3: Evaluate the effects of continuous pink noise throughout the night. Sub-aim 1: To determine if continuous noise (pink noise) per se improves or disturbs sleep, we will investigate changes in novel and classical indictors of sleep architecture and disturbance induced by pink noise relative to quiet baseline nights. Sub-aim 2: To determine if pink noise reduces sleep disturbance by traffic noise, we will investigate changes in sleep fragmentation and continuity, and cortical and autonomic arousal, from nights with both traffic noise and pink noise compared to nights with traffic noise only. The study will be conducted at in the University of Gothenburg sound environment laboratory (SEL). The SEL is a high fidelity research laboratory equipped to simulate a typical apartment, including three individually light-, sound- and vibration-isolated private bedrooms. Ceiling mounted speakers in each room allow us to create a realistic acoustic environment by transmitting sound exposures from the control room to each bedroom individually. This study has a prospective within-subjects cross-over design. Participants (N=12) will each spend five consecutive nights in the SEL with a sleep opportunity between 23:00-07:00. Daytime sleep will be prohibited, confirmed with measures of daytime activity via wrist actigraphy monitors worn continuously throughout the study. Three subjects will take part concurrently, in separate bedrooms. The first night is a habituation period to the study protocol and for familiarisation with the test procedures. Study nights 2-5 are the experimental nights and will be randomly assigned across participants using a Latin square design to avoid first-order carryover effects. Each subject will be exposed to one night of each of the following: Quiet night: No noise will be played, serving as a control night to assess individual baseline sleep, metabolic profile, and cognitive performance; Traffic noise night to determine consequences of noise-disrupted sleep; Pink noise night: To determine impact of continuous pink noise on sleep; Traffic + pink noise night: simultaneous traffic and pink noise at the same sound pressure levels as in the traffic-only and pink noise-only nights, to determine sleep-protecting effects of pink noise in the face of traffic noise. Each night we will record physiologic sleep with polysomnography (PSG) and cardiac activity with electrocardiography (ECG). Each study morning, subjects will provide a 2ml blood sample, complete cognitive testing and answer questionnaires and will depart the SEL to follow their normal daytime routine. They will return to the SEL at 20:00 each evening to prepare for sleep measurements. Caffeine will be prohibited after 15:00 and alcohol will be prohibited at all times. Because sound-induced auditory fatigue may be affected by noise exposure during participant's normal routines,60 they will wear a noise dosimeter during the week of the study to record their daytime noise exposure. Because extreme and/or variable dietary behaviour can affect the metabolome/lipoprotein profile, participants will be given guidance that they should eat a similar evening meal on each day of the laboratory study, confirmed with a food diary, The actual meal itself can be different for different study participants, because the study has a within-subjects design. Sleep will be recorded with ambulatory polysomnography (PSG) and cardiac activity with electrocardiography (ECG) and finger pulse photoplethysmogram. Data are recorded offline onto the sleep recorder, and will be downloaded and checked every study morning to ensure data quality. In addition to traditional sleep analysis performed by the research group at the University of Gothenburg, raw PSG data will be used to calculate the Odds Ratio Project, a novel metric of sleep depth and stability. Each study morning subjects will provide a 2 ml blood sample for plasma metabolomics analysis. To ensure reliable data, blood samples will be taken at the same time every day to mitigate circadian effects, before eating or drinking anything except water, and each sample will be handled in the same way i.e. centrifuged, aliquoted and stored in -80C freezers. Subjects will eat the same food each study evening to mitigate within-subject dietary effects on the blood metabolome. Each morning, subjects will complete a computerised cognitive test battery taking approximately 20 minutes, that includes 10 tests across a range of cognitive domains (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, balloon analog risk, psychomotor vigilance). Cognition data will be analysed to determine key measures of cognitive speed and accuracy, adjusting for practice effects and the difficulty of the stimulus set. Subjects will complete a battery of one-time validated questionnaires to measure their general health (SF-36), chronotype, noise sensitivity, habitual sleep quality, environmental sensitivity, and annoyance and sleep disturbance by noise. Subjects will also answer a questionnaire each study evening and morning, involving questions on sleepiness (Karolinska Sleepiness Scale), auditory fatigue, sleep disturbance by noise, and validated sleep and disturbance questions. Subjects will wear a noise dosimeter during the week of the study to record their daytime noise exposure (sound pressure level only, no actual sound recordings). Participants will wear a wrist actigraphy monitor continuously throughout the study period, and also for the week before the study, to confirm habitual sleep-wake times and to measure physical activity levels.

Official Title
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Metabolic and Cognitive Consequences of Noise-induced Sleep Disturbance

Conditions
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Sleep Disturbance, Noise Exposure, Sleep Hygiene, Metabolic Disturbance, Cognitive Change

Intervention / Treatment
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* Radiation: Pink noise exposure
* Radiation: Traffic noise


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 1) live in or around the city of Gothenburg area (Sweden) Exclusion Criteria: aged <18 or >30 years; habitual sleep and wake timings more than ±1 hour different from the study sleep times (i.e. habitual sleep time should be 22:00-00:00 and habitual wake time should be 06:00-08:00); BMI>25 kg/m2; regular sleep medication use (prescribed or over-the-counter); poor hearing acuity (measured during screening via pure tone audiometry); diagnosed with sleep disorders; indications of sleep apnea on the STOP-BANG questionnaire; shift work; smoking, vaping, snus, or other nicotine use; pre-existing use of white noise machines as a sleep aid.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 30 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: All participants will be exposed to each of the different noise exposure conditions. Each study night is treated as a separate arm of the crossover study. The order of the noise exposure conditions will be be randomly assigned across participants using a Latin square design to avoid first-order carryover effects. Each subject will be exposed to one night of each of the following: Quiet night: No noise will be played, serving as a control night to assess individual baseline sleep, metabolic profile, and cognitive performance; Traffic noise night to determine consequences of noise-disrupted sleep; Pink noise night: To determine impact of continuous pink noise on sleep; Traffic + pink noise night: simultaneous traffic and pink noise at the same sound pressure levels as in the traffic-only and pink noise-only nights, to determine sleep-protecting effects of pink noise in the face of traffic noise.
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: Control<br>Single study night with no noise exposure, to determine normal baseline sleep | |
| Experimental: Traffic noise<br>Single study night with traffic noise events, to determine consequences of sleep disturbance by traffic noise | Radiation: Traffic noise<br>* 120 traffic noise events (40 each of road, rail and aircraft), introduced at maximum sound pressure levels ranging between 45-65 dB LAS.max.<br>|
| Experimental: Pink noise<br>Single study night to measure the effects of a non-pharmacological intervention to promote sleep, pink noise. | Radiation: Pink noise exposure<br>* Continuous pink noise sound exposure at 45 dBA, throughout the whole night<br>|
| Experimental: Traffic noise + pink noise<br>Single study night with concurrent traffic noise events and continuous pink noise sound exposure. Night is used to determine attenuation of sleep disturbance by traffic noise due to introduction of pink noise. | Radiation: Pink noise exposure<br>* Continuous pink noise sound exposure at 45 dBA, throughout the whole night<br>Radiation: Traffic noise<br>* 120 traffic noise events (40 each of road, rail and aircraft), introduced at maximum sound pressure levels ranging between 45-65 dB LAS.max.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Metabolomics and lipids | Concentrations of 41 metabolites, including amino acids, amines, alcohols, carboxylic acids, choline, keto acids, sugars, and sulfones. Lipoprotein profile, including concentrations of triglycerides, cholesterol, phospholipids, and apolipoproteins. | On each of the five study mornings | 
| Baseline total sleep time | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Control night | 
| Total sleep time during exposure to nocturnal traffic | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the traffic noise night | 
| Total sleep time during exposure to pink noise | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the pink noise night | 
| Total sleep time during exposure to traffic noise + pink noise | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Traffic noise + pink noise night | 
| Total amount of baseline N1 sleep | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Control night | 
| Total amount of baseline N2 sleep | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Control night | 
| Total amount of baseline N3 sleep | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Control night | 
| Total amount of baseline rapid eye movement (REM) sleep | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Control night | 
| Total amount of N1 sleep during exposure to nocturnal traffic | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the traffic noise night | 
| Total amount of N2 sleep during exposure to nocturnal traffic | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the traffic noise night | 
| Total amount of N3 sleep during exposure to nocturnal traffic | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the traffic noise night | 
| Total amount of rapid eye movement (REM) sleep during exposure to nocturnal traffic | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the traffic noise night | 
| Total amount of N1 sleep during exposure to pink noise | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the pink noise night | 
| Total amount of N2 sleep during exposure to pink noise | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the pink noise night | 
| Total amount of N3 sleep during exposure to pink noise | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the pink noise night | 
| Total amount of rapid eye movement (REM) sleep during exposure to pink noise | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the pink noise night | 
| Total amount of N1 sleep during exposure to traffic noise + pink noise | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Traffic noise + pink noise night | 
| Total amount of N2 sleep during exposure to traffic noise + pink noise | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Traffic noise + pink noise night | 
| Total amount of N3 sleep during exposure to traffic noise + pink noise | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Traffic noise + pink noise night | 
| Total amount of rapid eye movement (REM) sleep during exposure to traffic noise + pink noise | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Traffic noise + pink noise night | 
| Baseline wakefulness after sleep onset (WASO) | Total number of minutes awake during the night after the first appearance of sleep of any stage. Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Control night | 
| Wakefulness after sleep onset (WASO) during exposure to nocturnal traffic | Total number of minutes awake during the night after the first appearance of sleep of any stage. Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Traffic noise night | 
| Wakefulness after sleep onset (WASO) during exposure to pink noise | Total number of minutes awake during the night after the first appearance of sleep of any stage. Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Pink noise night | 
| Wakefulness after sleep onset (WASO) during exposure to traffic noise + pink noise | Total number of minutes awake during the night after the first appearance of sleep of any stage. Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Traffic noise + pink noise night | 
| Baseline number of awakenings | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Control night | 
| Number of awakenings during exposure to nocturnal traffic | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Traffic noise night | 
| Number of awakenings during exposure to pink noise | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Pink noise night | 
| Number of awakenings during exposure to traffic noise + pink noise | Measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines | During the Traffic noise + pink noise night | 
| Baseline sleep onset latency (SOL) | Defined as the time from lights out to the first epoch of sleep measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines. | During the Control night | 
| Sleep onset latency (SOL) during exposure to nocturnal traffic | Defined as the time from lights out to the first epoch of sleep measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines. | During the Traffic noise night | 
| Sleep onset latency (SOL) during exposure to pink noise | Defined as the time from lights out to the first epoch of sleep measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines. | During the Pink noise night | 
| Sleep onset latency (SOL) during exposure to nocturnal traffic and pink noise | Defined as the time from lights out to the first epoch of sleep measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines. | During the Traffic noise + Pink noise night | 
| Baseline sleep efficiency | Defined as the percentage of time in bed spent in a non-wake sleep stage, measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines. | During the Control night | 
| Sleep efficiency during exposure to nocturnal traffic | Defined as the percentage of time in bed spent in a non-wake sleep stage, measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines. | During the Traffic noise night | 
| Sleep efficiency during exposure to pink noise | Defined as the percentage of time in bed spent in a non-wake sleep stage, measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines. | During the Pink noise night | 
| Sleep efficiency during exposure to nocturnal traffic and pink noise | Defined as the percentage of time in bed spent in a non-wake sleep stage, measured via polysomnography/EEG, scored according to American Academy of Sleep Medicine guidelines. | During the Traffic noise + pink noise night | 
| Baseline sleep depth assessed using the odds ratio product (ORP) | Average ORP over the full night, from 0 (never occurs during wake) to 2.5 (only occurs during wake). Derived via polysomnography/EEG measurements. | During the Control night | 
| Sleep depth assessed using the odds ratio product (ORP) during exposure to nocturnal traffic | Average ORP over the full night, from 0 (never occurs during wake) to 2.5 (only occurs during wake). Derived via polysomnography/EEG measurements. | During the Traffic noise night | 
| Sleep depth assessed using the odds ratio product (ORP) during exposure to pink noise | Average ORP over the full night, from 0 (never occurs during wake) to 2.5 (only occurs during wake). Derived via polysomnography/EEG measurements. | During the Pink noise night | 
| Sleep depth assessed using the odds ratio product (ORP) during exposure to traffic noise and pink noise | Average ORP over the full night, from 0 (never occurs during wake) to 2.5 (only occurs during wake). Derived via polysomnography/EEG measurements. | During the Traffic noise + pink noise night | 
| Spontaneous maximal change of odds ratio product (ORP) | Primary measure of acute sleep disruption by noise, calculated as the difference between the ORP in the 30s prior to noise onset and the maximum ORP during traffic noise. Averaged over 120 sham noise events during the night. | During the Control night | 
| Maximal change of odds ratio product (ORP) during exposure to traffic noise events | Primary measure of acute sleep disruption by noise, calculated as the difference between the ORP in the 30s prior to noise onset and the maximum ORP during traffic noise. Averaged over all 120 noise events during the night. | During the Traffic noise night | 
| Maximal change of odds ratio product (ORP) during exposure to traffic noise events | Primary measure of acute sleep disruption by noise, calculated as the difference between the ORP in the 30s prior to noise onset and the maximum ORP during traffic noise. Averaged over all 120 noise events during the night. | During the Traffic noise + pink noise night | 
| Spontaneous change of odds ratio product (ORP) during exposure to pink noise | Primary measure of acute sleep disruption by noise, calculated as the difference between the ORP in the 30s prior to noise onset and the maximum ORP during traffic noise. Averaged over 120 sham noise events during the night. | During the Pink noise night | 
| Baseline morning neurobehavioural speed | Average of one key speed indicator from each of 10 cognitive tests (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, balloon analog risk, psychomotor vigilance) | In the morning immediately after the Control night | 
| Morning neurobehavioural speed after exposure to nocturnal traffic | Average of one key speed indicator from each of 10 cognitive tests (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, balloon analog risk, psychomotor vigilance) | In the morning immediately after the Traffic noise night | 
| Morning neurobehavioural speed after exposure to pink noise | Average of one key speed indicator from each of 10 cognitive tests (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, balloon analog risk, psychomotor vigilance) | In the morning immediately after the Pink noise night | 
| Morning neurobehavioural speed after exposure to nocturnal traffic and pink noise | Average of one key speed indicator from each of 10 cognitive tests (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, balloon analog risk, psychomotor vigilance) | In the morning immediately after the Traffic noise + pink noise night | 
| Baseline morning neurobehavioural accuracy | Average of one key accuracy indicator from each of 9 cognitive tests (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, psychomotor vigilance) | In the morning immediately after the Control night | 
| Morning neurobehavioural accuracy after exposure to nocturnal traffic | Average of one key accuracy indicator from each of 9 cognitive tests (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, psychomotor vigilance) | In the morning immediately after the Traffic noise night | 
| Morning neurobehavioural accuracy after exposure to pink noise | Average of one key accuracy indicator from each of 9 cognitive tests (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, psychomotor vigilance) | In the morning immediately after the Pink noise night | 
| Morning neurobehavioural accuracy after exposure to nocturnal traffic and pink noise | Average of one key accuracy indicator from each of 9 cognitive tests (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, psychomotor vigilance) | In the morning immediately after the Traffic noise + pink noise night | 
| Baseline evening neurobehavioural speed | Average of one key speed indicator from each of 10 cognitive tests (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, balloon analog risk, psychomotor vigilance) | In the evening of the day following the Control night | 
| Evening neurobehavioural speed after exposure to nocturnal traffic | Average of one key speed indicator from each of 10 cognitive tests (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, balloon analog risk, psychomotor vigilance) | In the evening of the day following the Traffic noise night | 
| Evening neurobehavioural speed after exposure to pink noise | Average of one key speed indicator from each of 10 cognitive tests (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, balloon analog risk, psychomotor vigilance) | In the evening of the day following the Pink noise night | 
| Evening neurobehavioural speed after exposure to nocturnal traffic and pink noise | Average of one key speed indicator from each of 10 cognitive tests (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, balloon analog risk, psychomotor vigilance) | In the evening of the day following the Traffic noise + pink noise night | 
| Baseline evening neurobehavioural accuracy | Average of one key speed indicator from each of 9 cognitive tests (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, psychomotor vigilance) | In the evening of the day following the Control night | 
| Evening neurobehavioural accuracy after exposure to nocturnal traffic | Average of one key speed indicator from each of 9 cognitive tests (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, psychomotor vigilance) | In the evening of the day following the Traffic noise night | 
| Evening neurobehavioural accuracy after exposure to pink noise | Average of one key speed indicator from each of 9 cognitive tests (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, psychomotor vigilance) | In the evening of the day following the Pink noise night | 
| Evening neurobehavioural accuracy after exposure to nocturnal traffic and pink noise | Average of one key speed indicator from each of 9 cognitive tests (motor praxis, visual object learning, fractal 2-back, abstract matching, line orientation, emotion recognition, matrix reasoning, digit symbol substitution, psychomotor vigilance) | In the evening of the day following the Traffic noise + pink noise night | 
| Baseline Ethanol concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Trimethylamine-N-oxide concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline 2-Aminobutyric acid concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Alanine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Asparagine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Creatine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Creatinine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Glutamic acid concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Glutamine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Glycine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Histidine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Isoleucine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Leucine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Lysine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Methionine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline N,N-Dimethylglycine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Ornithine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Phenylalanine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Proline concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Sarcosine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Threonine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Tyrosine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Valine concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline 2-Hydroxybutyric acid concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Acetic acid concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Citric acid concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Formic acid concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Lactic acid concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Succinic acid concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Choline concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline 2-Oxoglutaric acid concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline 3-Hydroxybutyric acid concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Acetoacetic acid concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Acetone concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Pyruvic acid concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline D-Galactose concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Glucose concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Glycerol concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Baseline Dimethylsulfone concentration (mmol/L) | Determined from NMR analysis of blood plasma | In the morning immediately after the Control night | 
| Ethanol concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Trimethylamine-N-oxide concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| 2-Aminobutyric acid concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Alanine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Asparagine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Creatine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Creatinine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Glutamic acid concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Glutamine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Glycine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Histidine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Isoleucine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Leucine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Lysine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Methionine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| N,N-Dimethylglycine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Ornithine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Phenylalanine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Proline concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Sarcosine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Threonine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Tyrosine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Valine concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| 2-Hydroxybutyric acid concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Acetic acid concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Citric acid concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Formic acid concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Lactic acid concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Succinic acid concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Choline concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| 2-Oxoglutaric acid concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| 3-Hydroxybutyric acid concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Acetoacetic acid concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Acetone concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Pyruvic acid concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| D-Galactose concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Glucose concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Glycerol concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Dimethylsulfone concentration (mmol/L) after exposure to nocturnal traffic | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise night | 
| Ethanol concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Trimethylamine-N-oxide concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| 2-Aminobutyric acid concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Alanine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Asparagine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Creatine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Creatinine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Glutamic acid concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Glutamine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Glycine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Histidine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Isoleucine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Leucine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Lysine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Methionine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| N,N-Dimethylglycine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Ornithine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Phenylalanine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Proline concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Sarcosine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Threonine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Tyrosine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Valine concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| 2-Hydroxybutyric acid concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Acetic acid concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Citric acid concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Formic acid concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Lactic acid concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Succinic acid concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Choline concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| 2-Oxoglutaric acid concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| 3-Hydroxybutyric acid concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Acetoacetic acid concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Acetone concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Pyruvic acid concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| D-Galactose concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Glucose concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Glycerol concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Dimethylsulfone concentration (mmol/L) after exposure to nocturnal pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Pink noise night | 
| Ethanol concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Trimethylamine-N-oxide concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| 2-Aminobutyric acid concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Alanine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Asparagine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Creatine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Creatinine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Glutamic acid concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Glutamine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Glycine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Histidine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Isoleucine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Leucine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Lysine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Methionine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| N,N-Dimethylglycine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Ornithine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Phenylalanine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Proline concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Sarcosine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Threonine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Tyrosine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Valine concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| 2-Hydroxybutyric acid concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Acetic acid concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Citric acid concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Formic acid concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Lactic acid concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Succinic acid concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Choline concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| 2-Oxoglutaric acid concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| 3-Hydroxybutyric acid concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Acetoacetic acid concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Acetone concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Pyruvic acid concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| D-Galactose concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Glucose concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Glycerol concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 
| Dimethylsulfone concentration (mmol/L) after exposure to nocturnal traffic and pink noise | Determined from NMR analysis of blood plasma | In the morning immediately after the Traffic noise + pink noise night | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cardiovascular activation in response to noise | Change in heart rate (ECG) | Event-related, occurring within the time window of each discrete noise event, during each of the five study nights (23:00 to 07:00) | 
| Evening subjective sleepiness, assessed using the Karolinska Sleepiness Scale | The scale is a 9-level verbal scale from 1 - Extremely alert (best outcome) to 9 - Very sleepy. great effort to keep alert, fighting sleep (worst outcome) | Every study evening | 
| Morning subjective sleepiness, assessed using the Karolinska Sleepiness Scale | The scale is a 9-level verbal scale from 1 - Extremely alert (best outcome) to 9 - Very sleepy. great effort to keep alert, fighting sleep (worst outcome) | Every study morning | 
| Evening auditory fatigue | Perceived auditory fatigue, self-reported on a 5-point verbal scale, from 1 - Not at all (best outcome) to 5 - Extremely (worst outcome) | Every study evening | 
| Morning auditory fatigue | Perceived auditory fatigue, self-reported on a 5-point verbal scale, from 1 - Not at all (best outcome) to 5 - Extremely (worst outcome) | Every study morning | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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neurobehavioral performance, white noise, auditory fatigue, polysomnography, metabolomics