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Background and Objective: Sleep is an essential biological function that is critical for a healthy and fulfilling life. Available sleep quality assessment tools contain long questionnaires covering a long period of time, not taking into account daily physical activity patterns and individual lifestyles., Methods: In this paper we present SmartHypnos, an Android application that supports low-end devices. It enables users to report their sleep quality, monitor their physical activity and exercise intensity and gain personalized recommendations aimed at increasing sleep quality. The application functionalities are implemented through sleep quality evaluation questions, passive step counter, efficient data storage and Personal data are stored locally protecting user privacy. All these are integrated into a single interface that requires a single device, is of low learning difficulty and easy to use. SmartHypnos was evaluated during a pilot study that involved 48 adults (ages 18-50) that used the application for seven days and subsequently submitted their data, possible through the interface directly, and evaluated the application through an appropriate questionnaire., Results: SmartHypnos was rated positively by users, especially it terms of learnability, ease of use and stability, with a mean score over 8. Task completion time and ease, simplicity, user comfort and recommendation utility were scored with a mean over 7. The correlation between the features extracted were in accordance to prior works., Conclusions: SmartHypnos has the potential to become a sleep monitoring and intervention tool readily available to the general public, including vulnerable populations of low socio-economic status., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Rapid deconditioning and comprehensive deleterious physiological changes that result in bedrest affect every system, function and cell of the body. It was assumed that the inherent inactivity was the cause of the problem, and that exercise would restore good health (Vernikos, 2018). However, numerous studies exploring different types and bouts of exercise once a day during bedrest produced only partial benefits. The usual frequent signal to the vestibular system of the inner ear and the brain, of changing posture, such as standing up regularly during a normal day's activities, goes silent in the microgravity of space, in bedrest or when sitting continuously. Making frequent use of gravity stimulation by standing up often throughout the day accelerates rehabilitation. Though centrifugation has been used in the aerospace field, this is a new approach in clinical practice. Postural change apart, another type of Gravity Therapy is the passive riding of a human centrifuge with or without activity. Accelerated rehabilitation through Gravity Therapy can get patients up and about, back to health sooner, in addition to cutting practical and emotional costs of rehabilitation dramatically. KEY POINT: Other than getting a good night's sleep, spending too much time in bed is bad for your health., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Introduction: Investigations of biofeedback (BF) and neurofeedback (NF) training for nicotine addiction have been long documented to lead to positive gains in smoking status, behavior and to changes in brain activity. We aimed to: (a) evaluate a multi-visit combined BF/NF intervention as an alternative smoking cessation approach, (b) validate training-induced feedback learning, and (c) document effects on resting-state functional connectivity networks (rsFCN); considering gender and degree of nicotine dependence in a longitudinal design. Methods: We analyzed clinical, behavioral, and electrophysiological data from 17 smokers who completed five BF and 20 NF sessions and three evaluation stages. Possible neuroplastic effects were explored comparing whole-brain rsFCN by phase-lag index (PLI) for different brain rhythms. PLI connections with significant change across time were investigated according to different resting-state networks (RSNs). Results: Improvements in smoking status were observed as exhaled carbon monoxide levels, Total Oxidative Stress, and Fageström scores decreased while Vitamin E levels increased across time. BF/NF promoted gains in anxiety, self-esteem, and several aspects of cognitive performance. BF learning in temperature enhancement was observed within sessions. NF learning in theta/alpha ratio increase was achieved across baselines and within sessions. PLI network connections significantly changed across time mainly between or within visual, default mode and frontoparietal networks in theta and alpha rhythms, while beta band RSNs mostly changed significantly after BF sessions. Discussion: Combined BF/NF training positively affects the clinical and behavioral status of smokers, displays benefit in smoking harm reduction, plays a neuroprotective role, leads to learning effects and to positive reorganization of RSNs across time. Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT02991781., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Pandria, Athanasiou, Styliadis, Terzopoulos, Mitsopoulos, Paraskevopoulos, Karagianni, Pataka, Kourtidou-Papadeli, Makedou, Iliadis, Lymperaki, Nimatoudis, Argyropoulou-Pataka and Bamidis.)

Introduction: The idea behind the presentation of this case relates to utilizing space technology in earth applications with mutual benefit for both patients confined to bed and astronauts. Deconditioning and the progressiveness of skeletal muscle loss in the absence of adequate gravity stimulus have been of physiological concern. A robust countermeasure to muscle disuse is still a challenge for both immobilized patients and astronauts in long duration space missions. Researchers in the space medicine field concluded that artificial gravity (AG) produced by short-radius centrifugation on a passive movement therapy device, combined with exercise, has been a robust multi-system countermeasure as it re-introduces an acceleration field and gravity load. Methods: A short-arm human centrifuge (SAHC) alone or combined with exercise was evaluated as a novel, artificial gravity device for an effective rehabilitation strategy in the case of a stroke patient with disability. The results reveal valuable information on an individualized rehabilitation strategy against physiological deconditioning. A 73-year-old woman was suddenly unable to speak, follow directions or move her left arm and leg. She could not walk, and self-care tasks required maximal assistance. Her condition was getting worse over the years, also she was receiving conventional rehabilitation treatment. Intermittent short-arm human centrifuge individualized protocols were applied for 5 months, three times a week, 60 treatments in total. Results: It resulted in significant improvement in her gait, decreased atrophy with less spasticity on the left body side, and ability to walk at least 100 m with a cane. Balance and muscle strength were improved significantly. Cardiovascular parameters improved responding to adaptations to aerobic exercise. Electroencephalography (EEG) showed brain reorganization/plasticity evidenced through functional connectivity alterations and activation in the cortical regions, especially of the precentral and postcentral gyrus. Stroke immobility-related disability was also improved. Discussion: These alterations were attributed to the short-arm human centrifuge intervention. This case study provides novel evidence supporting the use of the short-arm human centrifuge as a promising therapeutic strategy in patients with restricted mobility, with application to astronauts with long-term muscle disuse in space., Competing Interests: JV is the director and founder of Thirdage LLC. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Kourtidou-Papadeli, Frantzidis, Machairas, Giantsios, Dermitzakis, Kantouris, Konstantinids, Bamidis and Vernikos.)

Objective: The aim of this study was to assess the mental health and sleep quality of aviation workers in Greece during the pandemic., Methods: A cross-sectional study of aviation workers in Greece was conducted., Results: Sleep disturbances were observed in 25.4% of our 548 participants, whereas 8.2% and 5.8% reported at least mild depressive and anxiety symptoms, respectively. The impact of the pandemic on their mental health was their primary concern, which increased for many active pilots according to their workload. Those infected mainly faced daily tiredness and fatigue. Smoking habits and high body mass index were a predisposition for more physical symptoms. Cabin crew and women generally yielded worse scores than the other groups., Conclusion: Fear of infection could explain mental health issues, whereas physical symptoms of those infected could be attributed to long-COVID (coronavirus disease) syndrome. Flight attendants' lower ratings may be due to more occupational exposure., Competing Interests: Conflicts of Interest: None declared., (Copyright © 2022 American College of Occupational and Environmental Medicine.)

Background: Living labs in the health and well-being domain have become increasingly common over the past decade but vary in available infrastructure, implemented study designs, and outcome measures. The Horizon 2020 Project Virtual Health and Wellbeing Living Lab Infrastructure aims to harmonize living lab procedures and open living lab infrastructures to facilitate and promote research activities in the health and well-being domain in Europe and beyond. This protocol will describe the design of a joint research activity, focusing on the use of innovative technology for both rehabilitation interventions and data collection in a rehabilitation context., Objective: With this joint research activity, this study primarily aims to gain insight into each living lab's infrastructure and procedures to harmonize health and well-being living lab procedures and infrastructures in Europe and beyond, particularly in the context of rehabilitation. Secondarily, this study aims to investigate the potential of innovative technologies for rehabilitation through living lab methodologies., Methods: This study has a mixed methods design comprising multiple phases. There are two main phases of data collection: cocreation (phase 1) and small-scale pilot studies (phase 2), which are preceded by a preliminary harmonization of procedures among the different international living labs. An intermediate phase further allows the implementation of minor adjustments to the intervention or protocol depending on the input that was obtained in the cocreation phase. A total of 6 small-scale pilot studies using innovative technologies for intervention or data collection will be performed across 4 countries. The target study sample comprises patients with stroke and older adults with mild cognitive impairment. The third and final phases involve Delphi procedures to reach a consensus on harmonized procedures and protocols., Results: Phase 1 data collection will begin in March 2022, and phase 2 data collection will begin in June 2022. Results will include the output of the cocreation sessions, small-scale pilot studies, and advice on harmonizing procedures and protocols for health and well-being living labs focusing on rehabilitation., Conclusions: The knowledge gained by the execution of this research will lead to harmonized procedures and protocols in a rehabilitation context for health and well-being living labs in Europe and beyond. In addition to the harmonized procedures and protocols in rehabilitation, we will also be able to provide new insights for improving the implementation of innovative technologies in rehabilitation., International Registered Report Identifier (irrid): PRR1-10.2196/34537., (©Sylvie Bernaerts, Nele A J De Witte, Vicky Van der Auwera, Bert Bonroy, Luiza Muraru, Panagiotis Bamidis, Christos Frantzidis, Chrysoula Kourtidou-Papadeli, Nancy Azevedo, Jokin Garatea, Idoia Muñoz, Rosa Almeida, Raquel Losada, Joyce Fung, Eva Kehayia, Anouk Lamontagne, Elaine de Guise, Cyril Duclos, Johanne Higgins, Sylvie Nadeau, Lucie Beaudry, Evdokimos Konstantinidis. Originally published in JMIR Research Protocols (https://www.researchprotocols.org), 10.03.2022.)

Short-arm human centrifugation (SAHC) is proposed as a robust countermeasure to treat deconditioning and prevent progressive disability in a case of secondary progressive multiple sclerosis. Based on long-term physiological knowledge derived from space medicine and missions, artificial gravity training seems to be a promising physical rehabilitation approach toward the prevention of musculoskeletal decrement due to confinement and inactivity. So, the present study proposes a novel infrastructure based on SAHC to investigate the hypothesis that artificial gravity ameliorates the degree of disability. The patient was submitted to a 4-week training programme including three weekly sessions of 30 min of intermittent centrifugation at 1.5-2 g . During sessions, cardiovascular, muscle oxygen saturation (SmO 2 ) and electroencephalographic (EEG) responses were monitored, whereas neurological and physical performance tests were carried out before and after the intervention. Cardiovascular parameters improved in a way reminiscent of adaptations to aerobic exercise. SmO 2 decreased during sessions concomitant with increased g load, and, as training progressed, SmO 2 of the suffering limb dropped, both effects suggesting increased oxygen use, similar to that seen during hard exercise. EEG showed increased slow and decreased fast brain waves, with brain reorganization/plasticity evidenced through functional connectivity alterations. Multiple-sclerosis-related disability and balance capacity also improved. Overall, this study provides novel evidence supporting SAHC as a promising therapeutic strategy in multiple sclerosis, based on mechanical loading, thereby setting the basis for future randomized controlled trials., Competing Interests: JV is the director and founder of the ThirdAge company. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Kourtidou-Papadeli, Frantzidis, Bakirtzis, Petridou, Gilou, Karkala, Machairas, Kantouris, Nday, Dermitzakis, Bakas, Mougios, Bamidis and Vernikos.)

Introduction: Experiments during spaceflight and simulated microgravity as head-down tilt bedrest, demonstrated the role of arterial stiffness among others, in microgravity induced cardiovascular pathologies and emphasized the need for a robust countermeasure., Aim: The purpose of the present study was to evaluate the use of a new countermeasure, consisting of a high intensity Reactive Sledge (RSL) jumps training protocol, to counteract changes in arterial stiffness during long term head down tilt bedrest (LTBR)., Methods: The participants enrolled in the study were 23 male, healthy volunteers, aged between 20 and 45 years, subjected to LTBR for 60 days and randomly assigned either to a control (11) or to a training sledge (12) group using RSL 3-4 times per week, as a countermeasure. Recorded values were systolic and diastolic blood pressure, heart rate and the user's arterial stiffness index., Results: Compared to baseline measurements, there was a deterioration in the values of arterial stiffness, systolic and diastolic blood pressure and heart rate, in both groups until day 35 of LTBR, interpreted as adaptation to the microgravity environment. From this day until the end of the experiment, arterial stiffness of the control group was constantly fluctuating, while constantly improving for the training group. During the recovery period, arterial stiffness values returned to the pre-experimental levels in both groups., Conclusions: Overall, arterial stiffness increased the longer the time spent in LTBR and the countermeasure was partially effective in preventing the observed phenomenon. German Clinical Trials Register (DRKS), DRKS00012946, September 18, 2017, retrospectively registered., (© 2021. Italian Society of Hypertension.)

Objective/background: Varenicline (VAR) is used for smoking cessation as it inhibits nicotine for binding on its receptors reducing nicotine dependence. VAR administration has been reported to affect sleep. The aim of this study was to evaluate possible changes in polysomnography (PSG) during VAR treatment (SmokeFreeBrain) in healthy smokers and smokers with obstructive sleep apnea (OSA)., Patients/methods: Thirty smokers (21 men) with 15.3 ± 10.2 PY, aged 32.8 ± 4.5 years, with BMI 28.6 ± 4 kg/m 2 , 16 without and 14 with OSA (92% males) were studied with PSG (Embletta MPR-Master) before treatment with VAR while smoking and 20-30 days during VAR administration and smoking cessation for at least 5 days., Results: No significant differences were observed in sleep macro architecture (N1, N2, N3, REM, Sleep Efficiency, Total Sleep Time) during VAR treatment apart from prolongation of sleep latency, N2 and N3 latency in both smokers with and without OSA. Apnea hypopnea index (AHI) was reduced in OSA smokers and especially during REM with a borderline increase of arousal index (ArI) and reduction of sleep efficiency (SE)., Conclusion: VAR treatment worsened sleep quality as a prolongation of sleep latency, N2 and N3 latency was observed. A marginal reduction of AHI was found in OSA patients, more significantly during REM. Due to the small sample size, further studies are needed to distinguish between the adverse reactions of VAR treatment and smoking cessation effects and to evaluate whether VAR may play a role in OSA treatment., (Copyright © 2021 Elsevier B.V. All rights reserved.)

We investigated the alterations of sleep regulation and promotion biomarkers as adenosine through its enzymes total adenosine deaminase (tADA)/adenosine deaminase (ADA2) in a microgravity analogue environment of head-down-tilt bed rest and their association with brain connectivity networks during non-rapid eye movement sleep stage 3 (NREM3), as well as the effectiveness of the reactive sledge (RSL) jump countermeasure to promote sleep. A total of 23 healthy male volunteers were maintained in 6° head-down-tilt position for 30 days and assigned either to a control or to a RSL group. Blood collection and polysomnographic recordings were performed on data acquisition day 1, 14, 30 and -14, 21, respectively. Immunochemical techniques and network-based statistics were employed for adenosine enzymes and cortical connectivity estimation. Our findings indicate that human blood adenosine biomarkers as well as NREM3 cortical functional connectivity are impaired in simulated microgravity. RSL physical activity intervened in sleep quality via tADA/ADA2 fluctuations lack, minor cortical connectivity increases, and limited degree of node and resting-state networks. Statistically significant decreases in adenosine biomarkers and NREM3 functional connectivity involving regions (left superior temporal gyrus, right postcentral gyrus, precuneus, left middle frontal gyrus, left postcentral gyrus, left angular gyrus and precuneus) of the auditory, sensorimotor default-mode and executive networks highlight the sleep disturbances due to simulated microgravity and the sleep-promoting role of RSL countermeasure. The head-down-tilt environment led to sleep deterioration projected through NREM3 cortical brain connectivity or/and adenosine biomarkers shift. This decline was more pronounced in the absence of the RSL countermeasure, thereby highlighting its likely exploitation during space missions., (© 2021 European Sleep Research Society.)

Purpose: Increasing the level of gravity passively on a centrifuge, should be equal to or even more beneficial not only to astronauts living in a microgravity environment but also to patients confined to bed. Gravity therapy (GT) may have beneficial effects on numerous conditions, such as immobility due to neuromuscular disorders, balance disorders, stroke, sports injuries. However, the appropriate configuration for administering the Gz load remains to be determined., Methods: To address these issues, we studied graded G-loads from 0.5 to 2.0g in 24 young healthy, male and female participants, trained on a short arm human centrifuge (SAHC) combined with mild activity exercise within 40-59% MHR, provided by an onboard bicycle ergometer. Hemodynamic parameters, as cardiac output (CO), stroke volume (SV), mean arterial pressure (MAP), systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) were analyzed, as well as blood gas analysis. A one-way repeated measures ANOVA and pairwise comparisons were conducted with a level of significance p < 0.05., Results: Significant changes in heart rate variability (HRV) and its spectral components (Class, Fmax, and VHF) were found in all g loads when compared to standing ( p < 0.001), except in 1.7 and 2.0g. There were significant changes in CO, cardiac index (CI), and cardiac power (CP) ( p < 0.001), and in MAP ( p = 0.003) at different artificial gravity (AG) levels. Dose-response curves were determined based on statistically significant changes in cardiovascular parameters, as well as in identifying the optimal G level for training, as well as the optimal G level for training. There were statistically significant gender differences in Cardiac Output/CO ( p = 0.002) and Cardiac Power/CP ( p = 0.016) during the AG training as compared to standing. More specifically, these cardiovascular parameters were significantly higher for male than female participants. Also, there was a statistically significant ( p = 0.022) gender by experimental condition interaction, since the high-frequency parameter of the heart rate variability was attenuated during AG training as compared to standing but only for the female participants ( p = 0.004)., Conclusion: The comprehensive cardiovascular evaluation of the response to a range of graded AG loads, as compared to standing, in male and female subjects provides the dose-response framework that enables us to explore and validate the usefulness of the centrifuge as a medical device. It further allows its use in precisely selecting personalized gravity therapy (GT) as needed for treatment or rehabilitation of individuals confined to bed., Competing Interests: JV is the director and founder of the ThirdAge company. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Kourtidou-Papadeli, Frantzidis, Gilou, Plomariti, Nday, Karnaras, Bakas, Bamidis and Vernikos.)

Sleep staging is a vital process conducted in order to analyze polysomnographic data. To facilitate prompt interpretation of these recordings, many automatic sleep staging methods have been proposed. These methods rely on bio-signal recordings, which include electroencephalography, electrocardiography, electromyography, electrooculography, respiratory, pulse oximetry and others. However, advanced, uncomplicated and swift sleep-staging-evaluation is still needed in order to improve the existing polysomnographic data interpretation. The present review focuses on automatic sleep staging methods through bio-signal recording including current and future challenges., Competing Interests: Conflicts of interest None to declare., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Understanding of the neuroscientific sleep mechanisms is associated with mental/cognitive and physical well-being and pathological conditions. A prerequisite for further analysis is the identification of the sleep macroarchitecture through manual sleep staging. Several computer-based approaches have been proposed to extract time and/or frequency-domain features with accuracy ranging from 80% to 95% compared with the golden standard of manual staging. However, their acceptability by the medical community is still suboptimal. Recently, utilizing deep learning methodologies increased the research interest in computer-assisted recognition of sleep stages. Aiming to enhance the arsenal of automatic sleep staging, we propose a novel classification framework based on convolutional neural networks. These receive as input synchronizations features derived from cortical interactions within various electroencephalographic rhythms (delta, theta, alpha, and beta) for specific cortical regions which are critical for the sleep deepening. These functional connectivity metrics are then processed as multidimensional images. We also propose to augment the small portion of sleep onset (N1 stage) through the Synthetic Minority Oversampling Technique in order to deal with the great difference in its duration when compared with the remaining sleep stages. Our results (99.85%) indicate the flexibility of deep learning techniques to learn sleep-related neurophysiological patterns.

In this paper we present the first steps in developing SmartHypnos, an easy to use and user friendly graphical user interface, which aims to provide polysomngographic data visualization and the detection and classification of sleep related events. Currently SmartHypnos supports the visualization of EEG, ECG, EOG and EMG signals, and respiratory signals such as nasal pressure, thermistor, oxygen saturation, thoracic and abdominal belt recordings. All these are incorporated into an interface that provides quick and effortless access to the signals mentioned above. The interface displays automatic sleep staging capabilities as well as the detection of apnea events with accuracy rates surpassing 80%. It is expected that SmartHypnos will reduce the time required to analyze sleep data and also reduce possible human errors.

In this paper we propose a novel methodology for investigating pathological sleep patterns through network neuroscience approaches. It consists of initial identification of statistically significant alterations in cortical functional connectivity patterns. The resulting sub-network is then analyzed by employing graph theory for estimating both global performance metrics (integration and specialization) as well as the significance of specific network nodes and their hierarchical organization. So, nodes with important role in network structure are recognized and their functionality is correlated with adenosine biomarker which is important in sleep regulation and promotion. The aforementioned pipeline is applied in a dataset of sleep data gathered during a microgravity simulation experiment. The analysis was performed on cortical resting-state networks involved in sleep physiology. It demonstrated the detrimental effects of microgravity which were more prominent for the group which did not perform reactive sledge jumps as a countermeasure.

Microgravity (MG) is one of the main problems that astronauts have to cope with during space missions. Long-duration space travel can have detrimental effects on human neurophysiology. Despite scientific efforts, these effects are still insufficiently investigated. Animal earth-based analogs are used to investigate potential nervous system associated perturbations that might occur during prolonged space missions. Hindlimb unloading, Tail suspension and Pelvic suspension models are currently used in MG studies. Loss of homeostasis of certain biological pathways in the nervous system can lead to the functioning and expression of receptors/genes, and the release and functioning of neurotransmitters and neuronal membrane ion channels into specific brain regions. The potential impact of MG on molecular mechanisms linked to neurophysiology through animal earth-based analogs is reviewed. The effect of molecular signalling pathways on the decline of neuronal connectivity and cognitive and neuroplasticity function under MG simulated conditions will be studied. The role of biomarkers including neurotransmitters, genes or receptors will be highlighted in the healthy and MG-affected brain. MG-mediated neurodegenerative mechanisms linked to learning and memory impairment will be highlighted. This review depicts the current rodent models applied to simulate MG ground based approaches and investigates the MG induced changes in the nervous system. The neuropathological profile of the above animal MG ground-based models can be comparable to the effects of ageing, anxiety and other neurological disorders. The advantages and limitations of the existing approaches are discussed. MG induced neurophysiology outcomes can be extrapolated to study other clinical applications., Competing Interests: None

This review addresses central nervous system (CNS) physiological changes during inter-planetary missions, specifically sensorimotor processing and sleep disorders. Isolation, confinement and induced stress factors also have a detrimental effect on cognitive and mental well-being, which could jeopardize mission accomplishment. Although countermeasures have been proposed, they mostly focus on cardiovascular and/or musculoskeletal systems. Long-term space flights require optimal cognitive performance of crew members during weightlessness for longer time periods independent of ground support. The present study describes various countermeasures trends in neuroscientific data acquisition and future perspectives of advanced analysis through functional connectivity and graph theory. These could be used to identify early deterioration patterns and evaluate the robustness of countermeasures employed.

Smoking and stress cooccur in different stages of a nicotine addiction cycle, affecting brain function and showing additive impact on different physiological responses. Resting-state functional connectivity has shown potential in identifying these alterations. Nicotine addiction has been associated with detrimental effects on functional integrity of the central nervous system, including the organization of resting-state networks. Prolonged stress may result in enhanced activation of the default mode network (DMN). Considering that biofeedback has shown promise in alleviating physiological manifestations of stress, we aimed to explore the possible neuroplastic effects of biofeedback training on smokers. Clinical, behavioral, and neurophysiological (resting-state EEG) data were collected from twenty-seven subjects before and after five sessions of skin temperature training. DMN functional cortical connectivity was investigated. While clinical status remained unaltered, the degree of nicotine dependence and psychiatric symptoms were significantly improved. Significant changes in DMN organization and network properties were not observed, except for a significant increase of information flow from the right ventrolateral prefrontal cortex and right temporal pole cortex towards other DMN components. Biofeedback aiming at stress alleviation in smokers could play a protective role against maladaptive plasticity of connectivity. Multiple sessions, individualized interventions and more suitable methods to promote brain plasticity, such as neurofeedback training, should be considered.

Sleep staging, the process of assigning labels to epochs of sleep, depending on the stage of sleep they belong, is an arduous, time consuming and error prone process as the initial recordings are quite often polluted by noise from different sources. To properly analyze such data and extract clinical knowledge, noise components must be removed or alleviated. In this paper a pre-processing and subsequent sleep staging pipeline for the sleep analysis of electroencephalographic signals is described. Two novel methods of functional connectivity estimation (Synchronization Likelihood/SL and Relative Wavelet Entropy/RWE) are comparatively investigated for automatic sleep staging through manually pre-processed electroencephalographic recordings. A multi-step process that renders signals suitable for further analysis is initially described. Then, two methods that rely on extracting synchronization features from electroencephalographic recordings to achieve computerized sleep staging are proposed, based on bivariate features which provide a functional overview of the brain network, contrary to most proposed methods that rely on extracting univariate time and frequency features. Annotation of sleep epochs is achieved through the presented feature extraction methods by training classifiers, which are in turn able to accurately classify new epochs. Analysis of data from sleep experiments on a randomized, controlled bed-rest study, which was organized by the European Space Agency and was conducted in the "ENVIHAB" facility of the Institute of Aerospace Medicine at the German Aerospace Center (DLR) in Cologne, Germany attains high accuracy rates, over 90% based on ground truth that resulted from manual sleep staging by two experienced sleep experts. Therefore, it can be concluded that the above feature extraction methods are suitable for semi-automatic sleep staging.

Men and women seem to process emotions and react to them differently. Yet, few neurophysiological studies have systematically investigated gender differences in emotional processing. Here, we studied gender differences using Event Related Potentials (ERPs) and Skin Conductance Responses (SCR) recorded from participants who passively viewed emotional pictures selected from the International Affective Picture System (IAPS). The arousal and valence dimension of the stimuli were manipulated orthogonally. The peak amplitude and peak latency of ERP components and SCR were analyzed separately, and the scalp topographies of significant ERP differences were documented. Females responded with enhanced negative components (N100 and N200), in comparison to males, especially to the unpleasant visual stimuli, whereas both genders responded faster to high arousing or unpleasant stimuli. Scalp topographies revealed more pronounced gender differences on central and left hemisphere areas. Our results suggest a difference in the way emotional stimuli are processed by genders: unpleasant and high arousing stimuli evoke greater ERP amplitudes in women relatively to men. It also seems that unpleasant or high arousing stimuli are temporally prioritized during visual processing by both genders.

Driver sleepiness due to sleep deprivation is a causative factor of many road accidents. Reducing the extent of the sleepy driving problem by developing a countermeasure device that will monitor the sleepiness level of the driver is crucial to improve the safety of the roads. Among numerous physiological measurements, the electroencephalographic (EEG) signal seems to be the most sensitive to detect sleepiness. Previous studies in the field have found consistent alterations of EEG signal during sleepy driving, though they face methodological limitations. We present here preliminary results from a real-driving experiment in which a more complete experimental setup was followed. The subjects were exposed to driving conditions twice: once after they had a normal sleep during the previous night, and once after they remained awake for at least 24 hours prior to the experiment. Significant alterations were observed in the alpha and beta EEG frequencies bands between the two sessions. Electroopthalmographic (EOG) measurements revealed an increased number of eye blinking during the sleep-deprived session in comparison to the control condition. Both measurements can be used for the successful design of a sleepiness detection countermeasure device.

Biomedical signal monitoring can counteract the risk of human operator error due to inattention or fatigue in safetycritical and restrictive environments, such as in aviation, space, automobile and heavy industrial machinery operation. Real-time biomedical data acquisition is changing through advances in microelectronics fabrication, bio-MEMS and power micro-generators. Such data acquisition and processing systems are becoming increasingly miniaturised, flexible and pervasive, while data is being collected from inside the human body as well as around it. In this paper we review two related research projects exploiting this technological convergence, discuss its implications and suggest future innovation prospects through further similar cross-disciplinary synergies.

The appeal of online education and distance learning as an educational alternative is ever increasing. To support and accommodate the over-specialized knowledge available by different experts, information technology can be employed to develop virtual distributed pools of autonomous specialized educational modules and provide the mechanisms for retrieving and sharing them. New educational standards such as SCORM and Healthcare LOM enhance this process of sharing by offering qualities like interoperability, accessibility, and reusability, so that learning material remains credible, up-to-date and tracks changes and developments of medical techniques and standards through time. Given that only a few e-learning courses exist in aerospace medicine the material of which may be exchanged among teachers, the aim of this paper is to illustrate the procedure of creating a SCORM compliant course that incorporates notions of recent advances in social web technologies. The course is in accordance with main educational and technological details and is specific to pulmonary disorders in aerospace medicine. As new educational trends place much emphasis in continuing medical education, the expansion of a general practitioner's knowledge in topics such as aviation and aerospace pulmonary disorders for crew and passengers becomes a societal requirement.

Inflight medical emergencies occur at a rate of 20 to 100 per million passengers, with a death rate of 0.1 to 1 per million. Cardiac, neurologic, and respiratory complaints comprise the more serious emergencies, as defined by aircraft diversion or use of ground-based medical assistance. In this paper, we review changes seen in the resting electrocardiogram in normal individuals exposed to high altitude, alongside important implications for patients with heart diseases in high altitude exposures and the possible effects of high altitude to permanent cardiac pacemakers. Arrhythmias in pilots and public safety are revisited together with the guidelines of the Joint Aviation Requirements (JAR) in Europe. The situation of Military flights is also discussed. Physicians ought to become knowledgeable about the specific medical job standards for their patients when asked to render opinions regarding fitness to fly. A database must be established to obtain prospective data that defines the risk of accidents in patients who are or were being treated for arrhythmias. Current guidelines could then be updated and revised as appropriate.

The traditional scientific approach of investigating the role of a variable on a living organism is to remove it or the ability of the organism to sense it. Gravity is no exception. Access to space has made it possible for us to begin the exploration of how gravity has influenced our evolution, our genetic make-up and our physiology. Identifying the thresholds at which each body system perceives, how much, how often, how long the gravity stimulus is needed and in which direction should it be presented for maximum effectiveness, is fundamental knowledge required for using artificial gravity as a therapeutic or maintenance countermeasure treatment in exploration missions. Here on earth, although surrounded by gravity we are negligent in using gravity as it was intended, to maintain the level of health that is appropriate to living in 1G. These, changes in lifestyle or pathologies caused by various types of injury can benefit as well from artificial gravity in much the same way as we are now considering for astronauts in space.

Introduction: Thousands of people work and perform everyday in high altitude environment, either as pilots, or shift workers, or mountaineers.The problem is that most of the accidents in this environment have been attributed to human error. The objective of this study was to assess complex cognitive performance as it interacts with respiratory insufficiency at altitudes of 8000 feet and identify the potential effect of hypoxia on safe performance., Methods: Twenty subjects participated in the study, divided in two groups: Group I with mild asymptomatic chronic obstructive pulmonary disease (COPD), and Group II with normal respiratory function. Altitude was simulated at 8000 ft. using gas mixtures., Results: Individuals with mild COPD experienced notable hypoxemia with significant performance decrements and increased number of errors at cabin altitude, compared to normal subjects, whereas their blood pressure significantly increased.

Objective: The objective of this study is the development and evaluation of efficient neurophysiological signal statistics, which may assess the driver's alertness level and serve as potential indicators of sleepiness in the design of an on-board countermeasure system., Methods: Multichannel EEG, EOG, EMG, and ECG were recorded from sleep-deprived subjects exposed to real field driving conditions. A number of severe driving errors occurred during the experiments. The analysis was performed in two main dimensions: the macroscopic analysis that estimates the on-going temporal evolution of physiological measurements during the driving task, and the microscopic event analysis that focuses on the physiological measurements' alterations just before, during, and after the driving errors. Two independent neurophysiologists visually interpreted the measurements. The EEG data were analyzed by using both linear and non-linear analysis tools., Results: We observed the occurrence of brief paroxysmal bursts of alpha activity and an increased synchrony among EEG channels before the driving errors. The alpha relative band ratio (RBR) significantly increased, and the Cross Approximate Entropy that quantifies the synchrony among channels also significantly decreased before the driving errors. Quantitative EEG analysis revealed significant variations of RBR by driving time in the frequency bands of delta, alpha, beta, and gamma. Most of the estimated EEG statistics, such as the Shannon Entropy, Kullback-Leibler Entropy, Coherence, and Cross-Approximate Entropy, were significantly affected by driving time. We also observed an alteration of eyes blinking duration by increased driving time and a significant increase of eye blinks' number and duration before driving errors., Conclusions: EEG and EOG are promising neurophysiological indicators of driver sleepiness and have the potential of monitoring sleepiness in occupational settings incorporated in a sleepiness countermeasure device., Significance: The occurrence of brief paroxysmal bursts of alpha activity before severe driving errors is described in detail for the first time. Clear evidence is presented that eye-blinking statistics are sensitive to the driver's sleepiness and should be considered in the design of an efficient and driver-friendly sleepiness detection countermeasure device.

The effectiveness of motor imagery training on cognitive performance was examined and the physiological mechanisms involved in the contribution of mental practice to motor learning were considered. The subject's mental effort during motor imagery was assessed by using psychophysiological measures and particularly eye blink activity as an 'indirect' measurement of subjects' attention. An electronic flight simulation program (Multiple Attribute Task Battery--MATB) was used to assess performance. Twenty healthy volunteers participated in the study divided in two groups: the control group and the imagery-training group. The subjects of the imagery group were asked for additional imagery training. The subjects of the actual performing group were asked additionally to passively observe the task in order to have equal time of exposure to the task. Performance scores and physiological parameters such as heart rate, respiratory rate, eye blinking activity and muscular activity were recorded during all sessions. The results revealed significantly higher performance level of the imagery-training group than the control group. Heart rate and respiratory rate significantly increased during imagery sessions compared to rest. A slight electromyographic activity was observed during the imagination of movement. Our findings support the notion that mental practice improves motor performance in a task where spatiotemporal or dynamic control of the action is highly required. The effects of mental practice on motor performance could be explained by the existence of a top-down mechanism based on the activation of a central representation of the movements, since the vegetative activation during motor imagery seems to be centrally controlled.

Objective: The objective of this study was the development and evaluation of nonlinear electroencephalography parameters which assess hypoxia-induced EEG alterations, and describe the temporal characteristics of different hypoxic levels' residual effect upon the brain electrical activity., Methods: Multichannel EEG, pO2, pCO2, ECG, and respiration measurements were recorded from 10 subjects exposed to three experimental conditions (100% oxygen, hypoxia, recovery) at three-levels of reduced barometric pressure. The mean spectral power of EEG under each session and altitude were estimated for the standard bands. Approximate Entropy (ApEn) of EEG segments was calculated, and the ApEn's time-courses were smoothed by a moving average filter. On the smoothed diagrams, parameters were defined., Results: A significant increase in total power and power of theta and alpha bands was observed during hypoxia. Visual interpretation of ApEn time-courses revealed a characteristic pattern (decreasing during hypoxia and recovering after oxygen re-administration). The introduced qEEG parameters S1 and K1 distinguished successfully the three hypoxic conditions., Conclusions: The introduced parameters based on ApEn time-courses are assessing reliably and effectively the different hypoxic levels. ApEn decrease may be explained by neurons' functional isolation due to hypoxia since decreased complexity corresponds to greater autonomy of components, although this interpretation should be further supported by electrocorticographic animal studies., Significance: The introduced qEEG parameters seem to be appropriate for assessing the hypoxia-related neurophysiological state of patients in the hyperbaric chambers in the treatment of decompression sickness, carbon dioxide poisoning, and mountaineering.

The problem addressed in this work is sleepiness during driving, which often leads to accidents in the streets. Experiments with sleepy drivers took place and the EEG data were analysed in terms of non-linear methods. Sample entropy and phase synchronization variations were investigated within the signal sections corresponding to "driving events", i.e. driving mistakes or loss of control, as well as to periods of drowsiness and sleepiness, as compared to the periods of normal driving. Decreased sample entropy, indicating loss of complexity, and an increased phase synchronisation have been found in the preliminary study presented. The results are encouraging towards developing an alerting system for predicting and preventing driving accidents.

Objective: The objective of this study was to develop a novel quantitative multichannel EEG (qEEG) based analysis method, called Global Field Damping Time (GFDT), in order to detect potential EEG changes of patients admitted to the ICU with acute respiratory failure, and correlate them to the patients' recovery outcome predicting the optimal time-point to disconnect the patient from mechanical ventilation., Methods: Twenty-nine adult patients with acute respiratory failure out of 98 admitted to the Intensive Care Unit of Saint Paul General Hospital were enrolled, and among them only 15 completed the study. The patients were classified in 3 groups according to their outcome after 3 months follow-up. The patients were intubated with fraction of inspired oxygen (FiO2) of 100%. Neurological Deficit Scores (NDS) were measured 24 h after intubation to assess patients' neurological condition. Twenty-four hours after patient's intubation, FiO2 was decreased to 40% (weaning session), followed by a 5 min early recovery session, a 5 min recovery 1 session and a 5 min recovery 2 session. EEG recordings were performed during this experimental procedure. Multichannel EEG segments were processed and fitted into a multivariate autoregressive (mAR) model, and single channel EEG segments into a scalar autoregressive (sAR) model. The mAR and the sAR models of arbitrary order p were decomposed into mp and p oscillators and relaxators, respectively. Damping time of each oscillator and each relaxator, and the Global Field Damping Time (GFDT) as a weighted damping time were estimated for both mAR and sAR models., Results: A statistically significant increase of mAR model's GFDT during the weaning session was observed in the subjects of all groups. Comparing the 3 patients' groups, statistically significant differences for mAR model's GFDT were observed for the weaning and early recovery session. Linear regression analysis between NDS and mean mAR model's GFDT showed statistical significance during weaning session, early recovery session, and recovery 1 session. There was no statistical significance for SaO2 in the regression analysis with NDS. The sAR model's GFDT presented worst results in comparison with the mAR modelling GFDT in the identification of hypoxic conditions during weaning session and in the discrimination of patients with acute respiratory failure according to their neurological outcome., Conclusions: Global Field Damping Time as correlated to the patients' neurological outcome appears to be a simple, compact, and substantial novel indicator of cerebral hypoxia and a potential predictor of the optimal time-point to disconnect the patient from the ventilator., Significance: Quantitative EEG seems to be an important tool for ICU clinicians assisting them to decide for the patients' optimal time-point to disconnect the patient from the ventilator.

Driver sleepiness due to sleep deprivation is a causative factor in 1% to 3% of all motor vehicle crashes. In recent studies, the importance of developing driver fatigue countermeasure devices has been stressed, in order to help prevent driving accidents and errors. Although numerous physiological indicators are available to describe an individual's level of alertness, the EEG signal has been shown to be one of the most predictive and reliable, since it is a direct measure of brain activity. In the present study, multichannel EEG data that were collected from 20 sleep-deprived subjects during real environmental conditions of driving are presented for the first time. EEG data's annotation made by two independent Medical Doctors revealed an increase of slowing activity and an acute increase of the alpha waves 5-10 seconds before driving events. From the EEG data that were collected, the Relative Band Ratio (RBR) of the EEG frequency bands, the Shannon Entropy, and the Kullback-Leibler (KL) Entropy were estimated for each one second segment. The mean values of these measurements were estimated for 5 minutes periods. Analysis revealed a significant increase of alpha waves relevant band ratios (RBR), a decrease of gamma waves RBR, and a significant decrease of KL entropy when the first and the last 5-min periods were compared. A rapid decrease of both Shannon and K-L entropies was observed just before the driving events. Conclusively, EEG can assess effectively the brain activity alterations that occur a few seconds before sleeping/drowsiness events in driving, and its quantitative measurements can be used as potential sleepiness indicators for future development of driver fatigue countermeasure devices.

Background: Long-duration space missions, as well as emerging civilian tourist space travel activities, prompted review and assessment of data available to date focusing on cardiovascular risk and available risk mitigation strategies. The goal was the creation of tools for risk priority assessments taking into account the probability of the occurrence of an adverse cardiovascular event and available and published literature from spaceflight data as well as available risk mitigation strategies., Methods: An international group of scientists convened in Bellagio, Italy, in 2004 under the auspices of the Aerospace Medical Association to review available literature for cardiac risks identified in the Bioastronautics Critical Path Roadmap (versions 2000, 2004). This effort led to the creation of a priority assessment framework to allow for an objective assessment of the hazard, probability of its occurrence, mission impact, and available risk mitigation measures., Results/conclusions: Spaceflight data are presented regarding evidence/ no evidence of cardiac dysrhythmias, cardiovascular disease, and cardiac function as well as orthostatic intolerance, exercise capacity, and peripheral resistance in presyncopal astronauts compared to non-presyncopal astronauts. Assessment of the priority of different countermeasures was achieved with a tabular framework with focus on probability of occurrence, mission impact, compliance, practicality, and effectiveness of countermeasures. Special operational settings and circumstances related to sensitive portions of any mission and the impact of environmental influences on mission effectiveness are addressed. The need for development of diagnostic tools, techniques, and countermeasure devices, food preparation, preservation technologies and medication, as well as an infrastructure to support these operations are stressed. Selected countermeasure options, including artificial gravity and pharmacological countermeasures need to be systematically evaluated and validated in flight, especially after long-duration exposures. Data need to be collected regarding the emerging field of suborbital and orbital civilian space travel, to allow for sound risk assessment.

The perspective of long-duration flights for future exploration, imply more research in the field of human adaptation. Previous studies in rat muscles hindlimb suspension (HLS), indicated muscle atrophy and a change of fibre composition from slow-to-fast twitch types. However, the contractile responses to long-term unloading is still unclear. Fifteen adult Wistar rats were studied in 45 and 70 days of muscle unweighting and soleus (SOL) muscle as well as extensor digitorum longus (EDL) were prepared for electrophysiological recordings (single, twitch, tetanic contraction and fatigue) and histochemical stainings. The loss of muscle mass observed was greater in the soleus muscle. The analysis of electrophysiological properties of both EDL and SOL showed significant main effects of group, of number of unweighting days and fatigue properties. Single contraction for soleus muscle remained unchanged but there was statistically significant difference for tetanic contraction and fatigue. Fatigue index showed a decrease for the control rats, but increase for the HLS rats. According to the histochemical findings there was a shift from oxidative to glycolytic metabolism during HLS. The data suggested that muscles atrophied, but they presented an adaptation pattern, while their endurance in fatigue was decreased., (c2003 Elsevier Ltd. All rights reserved.)

In the Greek pilot of the e-Vital project, remote telemedicine services are provided to chronic cardiac and pulmonary patients who are not confined to a hospital (i.e. receiving home/ambulatory health care) with the aim of exploring the dynamics of interactive continuous chronic patient monitoring, particularly focusing on the impact on patient's quality of life, the patient's active involvement in their own care and according impact on the overall quality of healthcare provision, as well as the benefits for healthcare providers (time management, patient management, savings, etc). The current trial in progress validates the business potential of remote monitoring services and demonstrates the technical environment that enables patient-doctor interaction regardless of location and the according communication modes and protocols. The domain for applying the envisaged service is the private healthcare sector and the users groups include individual chronic patients with cardiac and pulmonary diseases. So far, from the patient's point of view, the service mainly appeals to patients with arrhythmias due to lightweight technology and easy processes involved in the transmission of 1-lead ECG. Asthma and COPD patients are also enthusiastic, as they can receive doctor advice in real time. From the health professional's point of view the service has real added value in the fields of diagnosis, prevention, monitoring and follow up. In the case of asthma and COPD the value of the service in diagnosis is even more apparent as these patients may be asymptomatic, when they visit their doctor and have exacerbations when they are at home. e-Vital in this case ensures that the healthcare professional will acquire the complete image of the patient condition. Finally, the experiences gained so far indicate that e-Vital could be particularly efficient in isolated areas, with shortage of experienced scientific personnel.

Caffeine is characterised as a central nervous system stimulant, also affecting metabolic and cardiovascular functions. A number of studies have demonstrated an effect of caffeine on the excretion of catecholamines and their metabolites. Urinary epinephrine and norepinephrine have been shown to increase after caffeine administration. Similar trends were observed in our study in adrenaline (ADR) and noradrenaline (NORADR) levels and additionally a dose dependent effect of caffeine. The effect of caffeine on cognitive performance, blood pressure, and catecholamines was tested under resting conditions and under mental workload. Each subject performed the test after oral administration of 1 cup and then 3 cups of coffee. Root mean square error (RMSE) for the tracking task was continuously monitored. Blood pressure was also recorded before and after each stage of the experiment. Catecholamines were collected and measured for three different conditions as: at rest, after mental stress alone, after one dose of caffeine under stress, and after triple dose of caffeine under stress. Comparison of the performance of each stage with the resting conditions revealed statistically significant differences between group of smokers/coffee drinkers compared with the other two groups of non-coffee drinkers/non-smokers and non-smokers/coffee drinkers. There was no statistically significant difference between the last two groups. There was an increase of urine adrenaline with 1 cup of coffee and statistically significant increase of urine noradrenaline. Both catecholamines were significantly increased with triple dose of caffeine. Mental workload increased catecholamines. There was a dose dependent effect of caffeine on catecholamines., (Copyright 2003 Elsevier Science (USA))

The effect of caffeine on the central nervous system and cardiorespiratory system was tested under resting conditions and while undertaking a multitask performance test. The subjects abstained from caffeine for a week before the study. Each subject performed the test after oral administration of 90 and 250 mg of caffeine on two separate days. Sum of Squares was recorded during the whole period of the study. Heart rate (HR) and respiration rates (RR) were continuously recorded and blood pressure (BP) was recorded before and after each stage of the experiment (Test(0), Test(1), Test(2), Test(3)). Sixteen healthy volunteers participated in the study divided into three groups: Group A, non-smokers and non-coffee drinkers; Group B, smokers and coffee drinkers; and Group C, non-smokers and coffee drinkers. Comparison of the performance of each stage with the resting conditions revealed statistically significant differences of group B compared to the other two groups and no significant differences between Groups A and C in both doses of caffeine. Non-coffee drinkers needed a low dose of caffeine for their optimal performance while a higher dose significantly increased their blood pressure. Coffee drinkers and smokers needed a higher dose of caffeine for optimal performance, which increased very quickly, but did not last and increased their BP. This increase in BP was not statistically significant, probably because of nicotine's effect. Heart rate was decreased and respiration rate increased significantly. The optimal performance was dose-dependent, increasing significantly with the higher dose of caffeine but with adverse effects on BP and RR.

A case of inflight cervical emphysema and pneumomediastinum secondary to a "blowout" fracture of the right lateral orbit and maxillary sinus is described. A 43-yr-old male was struck on the face by another passenger during a flight from Australia to Greece. The cause of the emphysema and its fast progression is discussed with respect to the anatomic relations of the facial and cervical subcutaneous space and the mediastinum. The injured passenger was treated 3 h after arrival in Thessaloniki, Greece. This case demonstrates a potential complication of a "blowout" orbital fracture during flight. The condition should be recognized by emergency department personnel with the patient kept under observation and symptomatic treatment initiated. Prophylactic antibiotics should be considered.