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High heart rate variability (HRV) is increasingly recognized as an indicator of a healthy regulatory system, reflecting the dynamic balance between sympathetic (SNS) and parasympathetic (PSNS) nervous system activity. According to the neurovisceral integration model, this balance is managed by the central autonomic network (CAN), comprised of specific brain regions involved in emotional, attentional, and autonomic regulation. HRV thus reflects the performance of the cognitive, affective, and autonomic regulation system. Numerous studies support the relationship between HRV and the CAN, including research on HRV biofeedback training (HRVBF). Studies on the effectiveness of HRVBF for professions such as police officers have shown improvements in self-regulation, decision-making, and performance. However, few studies have specifically explored HRVBF's influence on HRV metrics in police officers, highlighting a need for further research. This study addresses this gap by randomly assigning 27 Icelandic police officers to intervention or wait-list control groups. The intervention group underwent a five-week HRVBF program, including group and individual training sessions. Results showed significant increases in HRV metrics for the intervention group, indicating improved autonomic function and stress resilience. Mental resilience increased significantly as measured by subjective measures of attentional control, mindful awareness, and reduced fatigue. These findings support the efficacy of HRVBF in enhancing HRV and mental resilience for police officers, suggesting its applicability and potential for integration into existing training programs., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

In-laboratory polysomnography, the gold-standard for diagnosing sleep disorders, is resource-demanding and not conducive to multiple night evaluations. Ambulatory polysomnography, especially when self-applied, could be a viable alternative. This study aimed to assess the feasibility and reliability of self-applied polysomnography over three consecutive nights in untrained participants, assessing: technical success rate; comparing sleep diagnostic variables from single and multiple nights; and evaluating participants' subjective experience. Data were collected from 78 participants (55.1% females) invited to test a self-applicable polysomnography device for three consecutive nights at home. The technical success rate for valid sleep recordings was 82.5% out of 234 planned study nights, with 87.2% of participants obtaining at least two valid nights. Misclassification of obstructive sleep apnea severity was higher in participants with mild OSA (21.4%) compared with those with moderate-to-severe obstructive sleep apnea or no obstructive sleep apnea. Sleep efficiency and wake after sleep onset showed improvement from Night 1 to Night 3 (p < 0.001), and the mean polysomnography set-up time decreased significantly over this period. Participants reported moderate-to-high satisfaction with the device (System Usability Scale score 71.2 ± 12.4). The findings suggest that self-applied polysomnography is a feasible diagnostic method for untrained individuals at risk for sleep disorders, and that multiple night assessments can improve diagnostic precision for mild obstructive sleep apnea cases., (© 2024 The Author(s). Journal of Sleep Research published by John Wiley & Sons Ltd on behalf of European Sleep Research Society.)

Most of the studies on the effect of trait positive affect (PA) and cardiovascular activity have focused on heart rate (HR) and blood pressure (BP) rather than heart rate variability (HRV). However, trait PA might sustain homeostasis for the autonomic system (ANS) by reducing activity in the sympathetic system (SNS) and increasing the activity in the parasympathetic system (PNS). A common index for the PNS is the vagal tone measured indirectly through HRV. The present study assessed whether trait PA influences cardiovascular response to various stress tasks by monitoring participants' HRV measured by RMSSD (root mean square of successive differences) along with HR and interbeat interval (IBI). A total of 54 participants performed various cognitive tasks and Trier Social Stress Tasks while their vital signs were monitored, and trait PA was measured with PANAS. The cognitive tasks included both high- and low-stress tasks, including fatigue-inducing 20 min Stroop tasks. The results showed overall higher HRV as measured by RMSSD for participants who have higher levels of trait PA, indicating more PNS activity compared with low-trait-PA individuals, particularly at the end of the task performance during the fatigue induction. High-trait-PA individuals also had a lower HR during the fatigue-inducing task and a higher IBI. The results support previous work by further indicating a more adaptive response and consequently better emotional regulation for high-trait-PA individuals in a complex, prolonged task setting.

When we experience psychological challenges in the environment, our heart rate usually rises to make us more able to solve the task, but there is an individual difference in cardiovascular reactivity (CVR). Extreme CVR to environmental demands has been associated with worse health outcomes, with blunted CVR (little or no rise in heart rate) related to maladaptive behavior, including depression. The blunted CVR has been explained by motivational disengagement, which involves giving up on a task when facing obstacles. Disengagement is thought to be a habitual response that people might not be aware of, and, therefore, objective measures such as test performance might serve as a good measure of engagement. In this study, 66 participants solved different cognitive tasks while their CVR was measured. The aim was to test the association between test performance and reactivity, measured with the difference in heart rate at baseline and the mean heart rate while solving the tasks. Our results show a significant association between reactivity scores and performance in all tests, of various difficulty, indicating that blunted cardiovascular reactivity predicts poorer cognitive performance. Furthermore, we find an association between reactivity in one test and the performance in the other tests, suggesting that disengagement from environmental demands can be more general and not depend on the task at hand. The results, therefore, support earlier research suggesting that blunted CVR is associated with worse cognitive performance, and extends the literature by indicating that disengagement could be a more general maladaptive response to the environment.

Obstructive sleep apnea is linked to severe health consequences such as hypertension, daytime sleepiness, and cardiovascular disease. Nearly a billion people are estimated to have obstructive sleep apnea with a substantial economic burden. However, the current diagnostic parameter of obstructive sleep apnea, the apnea-hypopnea index, correlates poorly with related comorbidities and symptoms. Obstructive sleep apnea severity is measured by counting respiratory events, while other physiologically relevant consequences are ignored. Furthermore, as the clinical methods for analysing polysomnographic signals are outdated, laborious, and expensive, most patients with obstructive sleep apnea remain undiagnosed. Therefore, more personalised diagnostic approaches are urgently needed. The Sleep Revolution, funded by the European Union's Horizon 2020 Research and Innovation Programme, aims to tackle these shortcomings by developing machine learning tools to better estimate obstructive sleep apnea severity and phenotypes. This allows for improved personalised treatment options, including increased patient participation. Also, implementing these tools will alleviate the costs and increase the availability of sleep studies by decreasing manual scoring labour. Finally, the project aims to design a digital platform that functions as a bridge between researchers, patients, and clinicians, with an electronic sleep diary, objective cognitive tests, and questionnaires in a mobile application. These ambitious goals will be achieved through extensive collaboration between 39 centres, including expertise from sleep medicine, computer science, and industry and by utilising tens of thousands of retrospectively and prospectively collected sleep recordings. With the commitment of the European Sleep Research Society and Assembly of National Sleep Societies, the Sleep Revolution has the unique possibility to create new standardised guidelines for sleep medicine., (© 2022 European Sleep Research Society.)

Neurocognitive tests offer objective and reliable assessment of patients' status and progress. However, there is no consensus on how to use neurocognitive assessment in sleep disorder research. An effective use of neurocognitive assessment must be based on standardized practices and have a firm theoretic basis. The aim of this review is to offer an overview of how different tests have been used in the field, mapping each test onto a corresponding cognitive domain and propose how to move forward with a suggested cognitive battery of tests covering all major cognitive domains., Competing Interests: Disclosure The authors have nothing to disclose. The work of the authors is sponsored in part by the Sleep Revolution, which has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 965417 and by NordForsk (NordSleep project 90458-06111) via the Icelandic Centre for Research., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Women's football has been far less studied than men's. This work's objectives were to: (1) analyze the differences in psychological skills, mental toughness (MT), and anxiety in women football players according to their level (national team, first division, and second division); and (2) predict those three levels (using a multivariate model) according to the players' psychological skills, mental toughness, and anxiety. One hundred and forty-two Icelandic women football players (23.5 ± 3.5 years) participated in the study. They were classified into three groups according to their level: national team, and first and second divisions. Three questionnaires were used: the Test of Performance Strategies Questionnaire, the Sport Mental Toughness Questionnaire, and the Sport Anxiety Scale-2 questionnaire. A one-way ANOVA with Bonferroni post hoc correction was used to examine differences between teams. Applying a classification tree analysis, the participants were classified into three groups according to their level. There were few differences between the three groups in psychological skills, but in mental toughness and anxiety the national team had the highest and lowest values respectively, and the first and second division players differed in relaxation in competition (TOPS), total score and confidence (SMTQ), and worry (SAS-2). The classification tree correctly classified 54.9% of the sample with the variables total score (SMTQ) and activation in practice (TOPS). Therefore, given the relevance that psychological attributes appear to have for women football players' performance, it would seem indispensable to incorporate the figure of the sports psychologist into national and club teams., (© 2019 Scandinavian Psychological Associations and John Wiley & Sons Ltd.)

Cardiovascular measures have been found to be sensitive to task onset and offset, but are less sensitive to adjacent levels of increasing cognitive workload. A potential confound in the literature is the disregard of individual differences in cardiovascular reactivity. In particular, the individuals' working memory capacity (WMC) is likely to play a role in cardiovascular reactivity to workload. A total of 98 university students performed four cognitive tasks that varied in their level of workload. The operation span (OSPAN) task was used to measure the participants' WMC. A variety of cardiovascular measures were gathered in real time during the experiment. Derived measures of blood pressure regulation were also calculated. In line with what was hypothesized, cardiovascular measures detected workload onset and offset but did not consistently distinguish between the individual task levels. Furthermore, a significant interaction between workload levels and WMC showed that cardiovascular profile varied depending on WMC scores. In addition, WMC negatively predicted subjective ratings of task difficulty as well as task performance, with subjective estimation of task difficulty and error increasing as WMC decreased. The results suggest that WMC may play a critical role in determining how individuals react to increased cognitive workload., (Copyright © 2017 Elsevier B.V. All rights reserved.)