Descent into sleep is accompanied by disengagement of the conscious brain from the external world It follows that this process should be associated with reduced neural activity in regions of the brain known to mediate interaction with the environment We examined blood oxygen dependent (BOLD) signal functional connectivity using conventional seed-based analyses in 3 primary sensory and 3 association networks as normal young adults transitioned from wakefulness to light sleep while lying immobile in the bore of a magnetic resonance imaging scanner Functional connectivity was maintained in each network throughout all examined states of arousal Indeed, correlations within the dorsal attention network modestly but significantly increased during light sleep compared to wakefulness Moreover, our data suggest that neuronally mediated BOLD signal variance generally increases in light sleep These results do not support the view that ongoing BOLD fluctuations primarily reflect unconstrained cognition Rather, accumulating evidence supports the hypothesis that spontaneous BOLD fluctuations reflect processes that maintain the integrity of functional systems in the brain

https://www.pnas.org/content/pnas/106/11/4489.full.pdf

Cortical network functional connectivity in the descent to sleep.

Background: An association has been reported between long-term exposure to road traffic noise and the risk of myocardial infarction (MI), but the evidence is limited and inconclusive. No previous study has simultaneously analyzed the role of exposure to noise and air pollution from road traffic in the risk of MI. Methods: A population-based case-control study on MI was conducted 1992-1994 in Stockholm County. Participants answered a questionnaire and underwent a physical examination. Residential exposure to noise and air pollution from road traffic between 1970 and 1992-1994 was assessed for 3666 participants (1571 cases of MI and 2095 controls), based on residential history combined with information on traffic intensity and distance to nearby roads. Information was also obtained on factors potentially affecting the relationship between noise exposure and MI, such as noise annoyance. Results: The correlation between long-term individual exposure to noise and air pollution from traffic was high (r = 0.6). The adjusted odds ratio for MI associated with long-term road traffic noise exposure of 50 dBA or higher was 1.12 (95% confidence interval = 0.95-1.33). In a subsample, defined by excluding persons with hearing loss or exposure to noise from other sources, the corresponding odds ratio was 1.38 (1.11-1.71), with a positive exposure-response trend. No strong effect modification was apparent by sex or cardiovascular risk factors, including air pollution from road traffic. Conclusions: The results lend some support to the hypothesis that long-term exposure to road traffic noise increases the risk for MI.

Long-term exposure to road traffic noise and myocardial infarction.

Nocturnal road traffic noise: A review on its assessment and consequences on sleep and health.

Noise, sleep and poor health: Modeling the relationship between road traffic noise and cardiovascular problems.

The relationship between environmental noise and health is poorly understood but of fundamental importance to public health. This study estimated the relationship between noise sensitivity, noise annoyance and health-related quality of life in a sample of adults residing close to the Auckland International Airport, New Zealand. A small sample (n = 105) completed surveys measuring noise sensitivity, noise annoyance, and quality of life. Noise sensitivity was associated with health-related quality of life; annoyance and sleep disturbance mediated the effects of noise sensitivity on health.

https://www.mdpi.com/1660-4601/7/10/3579/pdf

Exploring the relationship between noise sensitivity, annoyance and health-related quality of life in a sample of adults exposed to environmental noise.

In order to determine the influence of noise sensitivity on sleep, subjective sleep quality, annoyance, and performance after nocturnal exposure to traffic noise, 12 women and 12 men (age range, 19-28 years) were observed during four consecutive nights over a three weeks period. After a habituation night, the participants were exposed with weekly permuted changes to air, rail and road traffic noise. Of the four nights, one was a quiet night (32 dBA), while three were noisy nights with exposure to equivalent noise levels of 39, 44, and 50 dBA in a permuted order. The traffic noise caused alterations of most of the physiological parameters, subjective evaluation of sleep, annoyance, and performance. Correlations were found between noise sensitivity and subjective sleep quality in terms of worsened restoration, decreased calmness, difficulty to fall asleep, and body movements. The results suggest that alterations of subjective evaluation of sleep were determined by physical parameters of the noise but modified by individual factors like noise sensitivity.

Associations between noise sensitivity and sleep, subjectively evaluated sleep quality, annoyance, and performance after exposure to nocturnal traffic noise

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Associations between noise sensitivity and sleep, subjectively evaluated sleep quality, annoyance, and performance after exposure to nocturnal traffic noise