Effect of Acute Hypoxia Exposure on the Availability of A Adenosine Receptors and Perfusion in the Human Brain.

In animal studies it has been observed that the inhibitory neuromodulator adenosine is released into the cerebral interstitial space during hypoxic challenges. Adenosine's actions on the A adenosine receptor (AAR) protect the brain from oxygen deprivation and overexertion through adjustments in cerebral blood flow, metabolism, and electric activity. Using 8-cyclopentyl-3-(3-[F]fluoropropyl)-1-propylxanthine ([F]CPFPX), a PET tracer for the AAR, we tested the hypothesis that hypoxia-induced adenosine release reduces AAR availability in the human brain.

Simulating microgravity with 60 days of 6 degree head-down tilt bed rest compromises sleep.

Astronauts in space often experience sleep loss. In the AGBRESA (Artificial Gravity Bed Rest) study, we examined 24 participants (mean age ± SD, 33 ± 9 years) during two months of 6 head-down tilt (HDT) bed rest, which is a well-established spaceflight analogue. Polysomnography was recorded during baseline (BDC-9), HDT (nights 1, 8, 30 and 58) and recovery (R, nights 1 and 12).

Chest compression quality decreases in hypoxic conditions simulating an airliner cabin at cruising altitude: a randomized, controlled, double-blind Manikin Study.

Air traveler numbers are predicted to reach 4.0 billion in 2024. Between 1/15,000-50,000 passengers will experience acute medical problems inflight with cardiac arrests requiring cardiopulmonary resuscitation (CPR) accounting for 0.

Effects of moderate alcohol consumption and hypobaric hypoxia: implications for passengers' sleep, oxygen saturation and heart rate on long-haul flights.

Background: Passengers on long-haul flights frequently consume alcohol. Inflight sleep exacerbates the fall in blood oxygen saturation (SpO) caused by the decreased oxygen partial pressure in the cabin. We investigated the combined influence of alcohol and hypobaric hypoxia on sleep, SpO and heart rate.

A genetic variation in the adenosine A2A receptor gene contributes to variability in oscillatory alpha power in wake and sleep EEG and A adenosine receptor availability in the human brain.

The EEG alpha rhythm (∼ 8-13 Hz) is one of the most salient human brain activity rhythms, modulated by the level of attention and vigilance and related to cerebral energy metabolism. Spectral power in the alpha range in wakefulness and sleep strongly varies among individuals based on genetic predisposition. Knowledge about the underlying genes is scarce, yet small studies indicated that the variant rs5751876 of the gene encoding A adenosine receptors (ADORA2A) may contribute to the inter-individual variation.

Associations between resting state brain activity and A adenosine receptor availability in the healthy brain: Effects of acute sleep deprivation.

Introduction: Previous resting-state fMRI (Rs-fMRI) and positron emission tomography (PET) studies have shown that sleep deprivation (SD) affects both spontaneous brain activity and A adenosine receptor (AAR) availability. Nevertheless, the hypothesis that the neuromodulatory adenosinergic system acts as regulator of the individual neuronal activity remains unexplored.

Methods: Therefore, fourteen young men underwent Rs-fMRI, AAR PET scans, and neuropsychological tests after 52 h of SD and after 14 h of recovery sleep.

Total Sleep Deprivation Increases Brain Age Prediction Reversibly in Multisite Samples of Young Healthy Adults.

Sleep loss pervasively affects the human brain at multiple levels. Age-related changes in several sleep characteristics indicate that reduced sleep quality is a frequent characteristic of aging. Conversely, sleep disruption may accelerate the aging process, yet it is not known what will happen to the age status of the brain if we can manipulate sleep conditions.

Sleep-Induced Hypoxia under Flight Conditions: Implications and Countermeasures for Long-Haul Flight Crews and Passengers.

Purpose: Recuperation during sleep on board of commercial long-haul flights is a safety issue of utmost importance for flight crews working extended duty periods. We intended to explore how sleep and blood oxygenation (in wake versus sleep) are affected by the conditions in an airliner at cruising altitude.

Methods: Healthy participants' sleep was compared between 4-h sleep opportunities in the sleep laboratory (n = 23; sleep lab, ie, 53 m above sea level) and in an altitude chamber (n = 20; flight level, ie, 753 hPa, corresponding to 2438 m above sea level).

Road traffic noise impacts sleep continuity in suburban residents: Exposure-response quantification of noise-induced awakenings from vehicle pass-bys at night.

Nocturnal traffic noise has been associated with adverse health outcomes in exposed residents. Precise quantification of traffic noise effects on sleep is thus of great importance. Here we establish an exposure-response relationship for the awakening probability due to intermittent road traffic noise in suburban residents.

Traffic noise-induced changes in wake-propensity measured with the Odds-Ratio Product (ORP).

Nocturnal traffic noise can disrupt sleep and impair physical and mental restoration, but classical sleep scoring techniques may not fully capture subtle yet clinically relevant alterations of sleep induced by noise. We used a validated continuous measure of sleep depth and quality based on automatic analysis of physiologic sleep data, termed Wake Propensity (WP), to investigate temporal changes of sleep in response to nocturnal noise events in 3-s epochs. Seventy-two healthy participants (mean age 40.

Cerebral A adenosine receptor availability in female and male participants and its relationship to sleep.

The neuromodulator adenosine and its receptors are mediators of sleep-wake regulation which is known to differ between sexes. We, therefore, investigated sex differences in A adenosine receptor (AAR) availability in healthy human subjects under well-rested conditions using [F]CPFPX and positron emission tomography (PET). [F]CPFPX PET scans were acquired in 50 healthy human participants (20 females; mean age ± SD 28.

Reliability and validity of a 3-min psychomotor vigilance task in assessing sensitivity to sleep loss and alcohol: fitness for duty in aviation and transportation.

Study Objectives: The psychomotor vigilance task (PVT) is a widely used objective method to measure sustained attention, but the standard 10-min version is often impractical in operational settings. We investigated the reliability and validity of a 3-min PVT administered on a portable handheld device assessing sensitivity to sleep loss and alcohol in relation to a 10-min PVT and to applied tasks.

Methods: A total of 47 healthy volunteers underwent a 12 consecutive days sleep lab protocol.

Short-Term Annoyance Due to Night-Time Road, Railway, and Air Traffic Noise: Role of the Noise Source, the Acoustical Metric, and Non-Acoustical Factors.

Field studies on traffic noise-induced annoyance have predominantly used estimated outside noise levels. We intended to complement existing knowledge with exposure-response relationships that are based on precise indoor noise measurements. Acoustic recordings inside the bedrooms of nightly road traffic and annoyance ratings in the following morning were obtained from 40 suburban residents (mean age 29.

Coffee effectively attenuates impaired attention in ADORA2A C/C-allele carriers during chronic sleep restriction.

Many people consume coffee to attenuate increased sleepiness and impaired vigilance and attention due to insufficient sleep. We investigated in genetically caffeine sensitive men and women whether 'real world' coffee consumption during a simulated busy work week counteracts disabling consequences of chronically restricted sleep. We subjected homozygous C-allele carriers of ADORA2A (gene encoding adenosine A receptors) to five nights of only 5 h time-in-bed.

ADORA2A variation and adenosine A receptor availability in the human brain with a focus on anxiety-related brain regions: modulation by ADORA1 variation.

Adenosine, its interacting A and A receptors, and particularly the variant rs5751876 in the A gene ADORA2A have been shown to modulate anxiety, arousal, and sleep. In a pilot positron emission tomography (PET) study in healthy male subjects, we suggested an effect of rs5751876 on in vivo brain A receptor (AAR) availability. As female sex and adenosinergic/dopaminergic interaction partners might have an impact on this rs5751876 effect on AAR availability, we aimed to (1) further investigate the pilot male-based findings in an independent, newly recruited cohort including women and (2) analyze potential modulation of this rs5751876 effect by additional adenosinergic/dopaminergic gene variation.

Adverse interaction effects of chronic and acute sleep deficits on spatial working memory but not on verbal working memory or declarative memory.

The accumulation of chronic sleep deficits combined with acute sleep loss is common in shift workers and increases the risk of errors and accidents. We investigated single and combined effects of chronic and acute sleep loss and recovery sleep on working memory performance (N-back task) and on overnight declarative memory recall (paired-associate lists) in 36 healthy participants. After baseline measurements, the chronic sleep restriction group (n = 21; mean [SD] age 26 [4] years) underwent 5 nights of sleep restriction (5-hr time in bed [TIB]), whereas the control group (n = 15; mean [SD] age 28 [6] years) had 8-hr TIB during those nights.

Sleeping with Elevated Upper Body Does Not Attenuate Acute Mountain Sickness: Pragmatic Randomized Clinical Trial.

Purpose: Acute mountain sickness commonly occurs following ascent to high altitude and is aggravated following sleep. Cephalad fluid shifts have been implicated. We hypothesized that sleeping with the upper body elevated by 30º reduces the risk of acute mountain sickness.

Impact of acute sleep deprivation on dynamic functional connectivity states.

Sleep deprivation (SD) could amplify the temporal fluctuation of spontaneous brain activities that reflect different arousal levels using a dynamic functional connectivity (dFC) approach. Therefore, we intended to evaluate the test-retest reliability of dFC characteristics during rested wakefulness (RW), and to explore how the properties of these dynamic connectivity states were affected by extended durations of acute sleep loss (28/52 hr). We acquired resting-state fMRI and neuropsychological datasets in two independent studies: (a) twice during RW and once after 28 hr of SD (n = 15) and (b) after 52 hr of SD and after 14 hr of recovery sleep (RS; n = 14).

Comparing the Effects of Road, Railway, and Aircraft Noise on Sleep: Exposure⁻Response Relationships from Pooled Data of Three Laboratory Studies.

Objectives: Air, road, and railway traffic, the three major sources of traffic noise, have been reported to differently impact on annoyance. However, these findings may not be transferable to physiological reactions during sleep which are considered to decrease nighttime recovery and might mediate long-term negative health effects. Studies on awakenings from sleep indicate that railway noise, while having the least impact on annoyance, may have the most disturbing properties on sleep compared to aircraft noise.

Cognitive impairments by alcohol and sleep deprivation indicate trait characteristics and a potential role for adenosine A receptors.

Trait-like differences in cognitive performance after sleep loss put some individuals more at risk than others, the basis of such disparities remaining largely unknown. Similarly, interindividual differences in impairment in response to alcohol intake have been observed. We tested whether performance impairments due to either acute or chronic sleep loss can be predicted by an individual's vulnerability to acute alcohol intake.

Reestablishment of individual sleep structure during a single 14-h recovery sleep episode after 58 h of wakefulness.

Sleep structure is highly stable within individuals but different between individuals. The present study investigated robustness of the individual sleep structure to extended total sleep deprivation. Seventeen healthy men spent a baseline night (23:00-07:00 hours), 58 h of sleep deprivation and a 14-h recovery night (17:00-07:00 hours) in the laboratory.

Recovery sleep after extended wakefulness restores elevated A adenosine receptor availability in the human brain.

Adenosine and functional A adenosine receptor (AAR) availability are supposed to mediate sleep-wake regulation and cognitive performance. We hypothesized that cerebral AAR availability after an extended wake period decreases to a well-rested state after recovery sleep. [F]CPFPX positron emission tomography was used to quantify AAR availability in 15 healthy male adults after 52 h of sleep deprivation and following 14 h of recovery sleep.

Circadian variation of metabotropic glutamate receptor 5 availability in the rat brain.

The metabotrophic subtype 5 glutamate receptor (mGluR5) plays a critical role in synaptic plasticity besides its involvement in numerous neurological disorders, such as depression. As mGluR5 availability in humans is altered in sleep deprivation, we hypothesized that mGluR5 availability underlies a circadian variation. To investigate whether mGluR5 underlies potential circadian changes we measured its density in a randomized fashion at six different daytimes in 11 adult Sprague-Dawley rats.