The effect of sleep restriction on cognitive performance in elite cognitive performers: a systematic review

Effects of 5-Week Brain Endurance Training on Fatigue and Performance in Elite Youth Epée Fencers

PURPOSE

To examine the effectiveness of 5 weeks of brain endurance training (BET) in reducing impairments in sustained attention, performance at a specific fencing test, and perceived fatigue after a cognitive fatiguing task in youth épée elite fencers during the preseason.

METHODS

Using a quasi-randomized controlled trial, 19 elite youth fencers (8 women, 18 [1] y) were divided into a BET (n = 11) or control (n = 8) group. Both groups trained for 5 sessions/wk during 5 weeks. The BET group completed the BET sessions before, during, or after fencing training, 3 or 4 times a week. The control group performed only fencing training. Before and after the 5 weeks, fencers performed a psychomotor vigilance test and fencing test before and after 40 minutes of a reverse Stroop task. Perceived fatigue was scored on a 10-cm visual analog scale.

RESULTS

After 5 weeks, perceived fatigue, reaction time, and number of lapses in the psychomotor vigilance test increased from before to after the reverse Stroop task only in the control group (P ≤ .011), with no pre-to-post difference for the BET group (P > .059). No differences were found in fencing-test performance (P > .07). Effort for the reverse Stroop task increased for both groups after the 5 weeks (P = .043). We observed an increase in perceived fatigue, reaction time, and number of lapses in the BET group before the fatiguing task (P ≤ .028).

CONCLUSION

BET reduced the negative effects of a cognitive fatiguing task on sustained attention, without a clear improvement in performance on the fencing test, and represents a possible tool to mitigate fatigue in fencing.

The Role of Sleep Quality and Sleepiness in the Relationship Between Cognitive Flexibility and Fatigue

This study aimed to determine the pathways linking cognitive flexibility to fatigue through the serial mediation effect of sleep quality and sleepiness in 564 healthy adults using various scales, including the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Chalder Fatigue Scale, and Cognitive Flexibility Inventory. Analysis was performed using two mediating variables (sleep quality and sleepiness) with age and gender as covariates. The simple mediation effect was evaluated using the Causal Step. The indirect effect was examined using bootstrap method and Sobel test. The total and direct effects of cognitive flexibility on fatigue were both found to be statistically significant. The research model revealed three significant indirect effects: cognitive flexibility affecting fatigue through sleep quality, cognitive flexibility affecting fatigue through sleepiness and cognitive flexibility affecting fatigue through both sleep quality and sleepiness. Additionally, serial mediation analysis showed that the relationship between cognitive flexibility and fatigue is sequentially mediated by sleep quality and sleepiness (B = -0.064, SE = 0.013, 95% CI: -0.070 to -0.017). All effects were confirmed through the 95% confidence intervals, which did not include zero, and with significant p values. These findings highlight the role of sleep quality and sleepiness as serial mediators of the relationship between cognitive flexibility and fatigue. The study's major contribution is to provide insight on the independent and serial mediating role of sleep quality and sleepiness in the relationship between cognitive flexibility to fatigue.

Effects of sleep deprivation on sports performance and perceived exertion in athletes and non-athletes: a systematic review and meta-analysis

Background

Sleep deprivation can significantly affect sports performance and the perception of fatigue. However, the impact of sleep deprivation on sports performance remains a subject of ongoing debate across different populations.

Objectives

This study aimed to investigate the effects of sleep deprivation on sports performance and ratings of perceived exertion (RPE) in different groups, as well as how different types of sleep deprivation affect these aspects.

Methods

This systematic review followed the PRISMA guidelines (PROSPERO CRD42023492792). Randomized controlled trials (RCTs) and randomized crossover studies published in any language or up to any date were eligible based on the P.I.C.O.S. criteria. The systematic search included databases such as PubMed, Cochrane, Embase, Web of Science, and EBSCO, covering studies up to September 2024. The Cochrane RoB 2 tool was used to assess the risk of bias. Meta-analysis was conducted using either a fixed-effect model or a random-effects model. This study conducted subgroup analyses based on different populations, types of sleep deprivation, and testing times.

Results

This review includes 45 studies, comprising 16 on aerobic endurance (AE) performance, 8 on anaerobic endurance (AnE) performance, 23 on explosive power (EP), 10 on maximum force (MF), 4 on speed, 4 on skill control, and 12 on rating of perceived exertion (RPE). The results indicate that sleep deprivation significantly impaired AE in athletes [SMD = -0.66; 95% CI (-1.28, -0.04); P = 0.04], as well as EP [SMD = -0.63; 95% CI (-0.94, -0.33); P < 0.00001], MF [SMD = -0.35; 95% CI (-0.56, -0.14); P = 0.001], speed [SMD = -0.52, 95% CI (-0.83, -0.22); P = 0.0008], skill control [SMD = -0.87; 95% CI (-1.7, -0.04); P = 0.04], and RPE [SMD = 0.39; 95% CI (0.11, 0.66); P = 0.006]. Additionally, AE was also reduced in healthy non-athletes [SMD = -1.02; 95% CI (-1.84, -0.21); P = 0.01]. During the sleep deprivation process, early sleep deprivation (PSDE) significantly reduced EP [SMD = -1.04; 95% CI (-1.58, -0.5); P = 0.0002], MF [SMD = -0.57; 95% CI (-0.94, -0.19); P = 0.003], speed [SMD = -0.78; 95% CI (-1.35, -0.2); P = 0.008], and RPE [SMD = 0.6; 95% CI (0.17, 1.02); P = 0.006]. Late sleep deprivation (PSDB) impacted speed [SMD = -0.57; 95% CI (-1.15, 0.01); P = 0.05], skill control [SMD = -2.12; 95% CI (-3.01, -1.24); P < 0.00001], and RPE [SMD = 0.47; 95% CI (0.02, 0.92); P = 0.04]. Overall, total sleep deprivation primarily affected AE [SMD = -0.56; 95% CI (-1.08, -0.05); P = 0.03]. In terms of testing phases, p.m. tests had a significant impact on AE [SMD = -1.4; 95% CI (-2.47, -0.34); P = 0.01], EP [SMD = -0.68; 95% CI (-1.06, -0.31); P = 0.0004], MF [SMD = -0.3; 95% CI (-0.51, -0.09); P = 0.005], skill control [SMD = -2.12; 95% CI (-3.01, -1.24); P < 0.00001], and RPE [SMD = 0.72; 95% CI (0.20, 1.24); P = 0.007]. In contrast, a.m. tests primarily affected speed [SMD = -0.81; 95% CI (-1.52, -0.1); P = 0.03] and RPE [SMD = 0.44; 95% CI (0.01, 0.86); P = 0.04].

Conclusion

Sleep deprivation significantly impairs athletes' performance across various domains, including AE, MF, speed, and skill control, while also exacerbating RPE. In contrast, although sleep deprivation also negatively affects the AE of healthy non-athletes. Furthermore, PSDE appears to have a more pronounced effect on sports performance overall. Additionally, performance assessments conducted in the p.m. have been shown to further impact sports performance. These findings are crucial for understanding how sleep deprivation impacts both athletes and non-athletes, particularly in the context of training and competitive settings.

Time Is a Tool: Evaluation of a Prolonged Casualty Care Curriculum With a Focus on Temporal Fidelity

INTRODUCTION

In current and anticipated future conflicts, including large-scale combat operations, medical teams are tasked to provide prolonged casualty care (PCC) or extended patient care that occurs when delays in evacuation exceed the team's capabilities. Although the principles of PCC are often taught to military medical providers using simulation, educators rarely dedicate the time to training required to simulate the prolonged nature of these encounters. Therefore, a lack of knowledge exists regarding which aspects of extended care may be lost in an accelerated training scenario.

MATERIALS AND METHODS

To close this knowledge gap within military medical education and training, we modified an existing PCC curriculum at the USU, Operation Gunpowder, to focus on temporal fidelity, extending the length of the simulated encounter to 21 hours. We used a qualitative phenomenological design to explore the students' experiences and perceptions by closely analyzing their assigned reflection papers.

RESULTS

We identified four themes from the students' reflection papers: (1) Recognized effects of fatigue, (2) navigated resource limitations, (3) realized the value of teamwork, and (4) noted the importance of communication and documentation. These themes revealed benefits of incorporating temporal fidelity into PCC training, including self-awareness of personal limits and possible strategies to mitigate fatigue when medical or operational mission requirements dictate sleep deprivation. Future studies are needed to determine other training scenarios that would benefit from adherence to temporal fidelity.

CONCLUSIONS

Wars and disasters require medical providers trained in PCC. Future educational activities aimed at teaching PCC should continue to incorporate temporal fidelity to help teach these valuable lessons.

The Effect of Total Sleep Deprivation on the Cognitive and In-Game Performance of Rocket League Esport Players

Purpose

It is presumed by many that acute sleep loss results in degraded in-game esports (competitive, organized video game play) performance. However, this has not been experimentally investigated to date. The objective of the current experiment was to elucidate whether ~29hrs of total sleep deprivation impacts in-game performance for the popular esport Rocket League.

Patients and Methods

Twenty skill-matched pairs (N = 40 total) were recruited. Within each pair, one participant was assigned to an intervention group (TSD), while the other was assigned to a control group (CON). Two test sessions occurred; one while both participants were rested (baseline), and the other while the CON participant was rested but the TSD participant was sleep deprived (experimental).

Results

Following total sleep deprivation, TSD participants reported higher Karolinska Sleepiness Scale-measured subjective sleepiness and lower subjective alertness and motivation, as well as worsened PVT response speed and ~5 times greater PVT lapse incidence, and worsened response speed on a two-choice categorization task. However, overall in-game Rocket League performance did not worsen due to total sleep deprivation. Exploratory analyses of performance indicators suggest a potential shift toward a simpler and safer strategy following sleep deprivation.

Conclusion

Following a bout of ~29hrs total sleep deprivation, overall in-game Rocket League performance remained unaffected. This presents as a promising finding given the high potential for acute pre-competition sleep disturbance in esports, though habitual sleep remains a concern for esport athletes.

A systematic and meta-analytic review of the impact of sleep restriction on memory formation

Modern life causes a quarter of adults and half of teenagers to sleep for less than is recommended (Kocevska et al., 2021). Given well-documented benefits of sleep on memory, we must understand the cognitive costs of short sleep. We analysed 125 sleep restriction effect sizes from 39 reports involving 1234 participants. Restricting sleep (3-6.5 hours) compared to normal sleep (7-11 hours) negatively affects memory formation with a small effect size (Hedges' g = 0.29, 95 % CI = [0.13, 0.44]). We detected no evidence for publication bias. When sleep restriction effect sizes were compared with 185 sleep deprivation effect sizes (Newbury et al., 2021) no statistically significant difference was found, suggesting that missing some sleep has similar consequences for memory as not sleeping at all. When the analysis was restricted to post-encoding, rather than pre-encoding, sleep loss, sleep deprivation was associated with larger memory impairment than restriction. Our findings are best accounted for by the sequential hypothesis which emphasises complementary roles of slow-wave sleep and REM sleep for memory.

Regional brain structure mediates the association between sleep quality and intellectual abilities: the moderating role of socioeconomic status

This study aims to reveal the association between sleep quality and crystallized intelligence (Gc), fluid intelligence (Gf), and the underlying brain structural basis. Using the data from the Human Connectome Project (N = 1087), we performed mediation analysis to explore whether regional brain structure related to sleep quality mediate the association between sleep quality and intellectual abilities, and further examined whether socioeconomic status (i.e., income and education level) moderate the mediation effect. Results showed that poorer sleep quality was associated with lower Gc rather than Gf, and worse sleep quality was associated with smaller volume and surface area in temporal lobe, including inferior temporal gyrus and middle temporal gyrus. Notably, temporal lobe structures mediated the association between sleep quality and Gc rather than Gf. Furthermore, socioeconomic status (i.e., income and education level) moderated the mediating effect, showing low socioeconomic status has a more significant mediating effect with stronger association between sleep quality and Gc as well as stronger association between temporal lobe structure and Gc in low socioeconomic status group. These findings suggest that individuals with higher socioeconomic status are less susceptible to the effect of sleep quality on Gc.

Impact of one night of sleep restriction on sleepiness and cognitive function: A systematic review and meta-analysis

Detrimental consequences of chronic sleep restriction on cognitive function are well established in the literature. However, effects of a single night of sleep restriction remain equivocal. Therefore, we synthesized data from 44 studies to investigate effects of sleep restriction to 2-6 h sleep opportunity on sleepiness and cognition in this meta-analysis. We investigated subjective sleepiness, sustained attention, choice reaction time, cognitive throughput, working memory, and inhibitory control. Results revealed a significant increase in subjective sleepiness following one night of sleep restriction (Standardized Mean Difference (SMD) = 0.986, p < 0.001), while subjective sleepiness was not associated with sleep duration during sleep restriction (β = -0.214, p = 0.039, significance level 0.01). Sustained attention, assessed via common 10-min tasks, was impaired, as demonstrated through increased reaction times (SMD = 0.512, p < 0.001) and attentional lapses (SMD = 0.489, p < 0.001). However, the degree of impaired attention was not associated with sleep duration (ps > 0.090). We did not find significant effects on choice reaction time, cognitive throughput, working memory, or inhibitory control. Overall, results suggest that a single night of restricted sleep can increase subjective sleepiness and impair sustained attention, a cognitive function crucial for everyday tasks such as driving.

Comparing the cognitive performance of action video game players and age-matched controls following a cognitively fatiguing task: A stage 2 registered report

Recent work demonstrates that those who regularly play action video games (AVGs) consistently outperform non-gamer (NG) controls on tests of various cognitive abilities. AVGs place high demands on several cognitive functions and are often engaged with for long periods of time (e.g., over 2 h), predisposing players to experiencing cognitive fatigue. The detrimental effects of cognitive fatigue have been widely studied in various contexts where accurate performance is crucial, including aviation, military, and sport. Even though AVG players may be prone to experiencing cognitive fatigue, this topic has received little research attention to date. In this study, we compared the effect of a cognitively fatiguing task on the subsequent cognitive performance of action video game players and NG control participants. Our results indicated AVGs showed superior spatial working memory and complex attention abilities while showing no difference from NGs on simple attention performance. Additionally, we found that our cognitive fatigue and control interventions did not differentially affect the cognitive performance of AVGs and NGs in this study. This pre-registered study provides evidence that AVGs show superior cognitive abilities in comparison to a non-gaming population, but do not appear more resilient to cognitive fatigue.

The sleep, circadian, and cognitive performance consequences of watchkeeping schedules in submariners: A scoping review

Watchkeeping schedules are essential for maintaining submarine operations, but come with human risk factors including, disrupted sleep, circadian misalignment, and cognitive deficits. There is now an emerging literature examining the strengths and weaknesses of submarine watchkeeping schedules trialled in the field and under simulated laboratory conditions. The aim of this scoping review was to summarise this literature. A systematic search of peer-reviewed journal articles and industry reports listed in MEDLINE, PsychINFO, PubMed, Scopus, Embase and Google Scholar undertaken in May 2023 returned 7298 papers. Following screening procedures, 13 studies were identified for inclusion. The findings revealed that sleep was sufficiently preserved regardless of watchkeeping schedule (total sleep time = 5.46-7.89 h), circadian misalignment was greater for non-24 h schedules, and longer off-watch periods were associated with better cognitive performance. Taken together, when comparing between watchkeeping schedules, the present findings suggest that the 4 h-on/8 h-off and 8 h-on/16 h-off schedules may be a good compromise when balancing human risk factors and operational demands. However, submarines are complex and challenging environments to study and there is a need to expand the literature. More research comparing watchkeeping schedules is needed. Future studies should focus on cognitive performance measures, such as problem-solving, prioritisation and executive decision-making to address present shortcomings, and an examination of sleep and circadian countermeasures to assist with adaptation either initiated pre-deployment or by modifying the submarine environment itself should be considered.

Physical Activity Patterns, Circadian Rhythms, and Aggressive and Suicidal Behavior among a Larger Sample of the General Population Aged 15 to 34 Years

BACKGROUND

From a psychological perspective, aggressive behavior, non-suicidal self-injury and suicidal behavior could be considered dysfunctional coping strategies. Poor sleep patterns may further increase such dysfunctional coping. In contrast, regular physical activity may have the power to counteract such dysfunctional coping. Given this background, the aim of the present study was to combine categories of circadian rhythms as a proxy of normative sleep patterns and categories of physical activity patterns, and to associate these categories with aggressive behavior, non-suicidal self-injury and suicidal behavior among a larger sample of adolescents and young adults, aged 15 to 34 years.

METHOD

A total of 2991 (55.6% females) individuals aged 15 to 34 years of the so-called Ravansar non-communicable disease cohort study (RaNCD) took part in this study. Participants completed self-rating questionnaires covering circadian-related sleep patterns, regular physical activity, socio-demographic information and dimensions of aggression, non-suicidal self-injury and suicidal behavior.

RESULTS

In a first step, both sleep patterns (circadian rhythm disorder: yes vs. no) and physical activity patterns (high vs. low) were dichotomized. Next, participants were assigned to one of four prototypical clusters: No circadian sleep disorders and high physical activity ("Hi-Sleep-Hi-PA"); no circadian sleep disorders and low physical activity ("Hi-Sleep-Lo-PA"); circadian sleep disorders and high physical activity ("Lo-Sleep-Hi-PA"); circadian sleep disorders and low physical activity ("Lo-Sleep-Lo-PA"). Projecting these four clusters on dimensions of aggressive behavior, non-suicidal self-injury and suicidal behavior, the following findings were observed: Participants of the "Hi-Sleep-Hi-PA" reported the lowest scores for aggressive behavior, self-injury and suicidal behavior, compared to participants of the "Lo-Sleep-Lo-PA" cluster. No differences for aggressive behavior, self-injury and suicidal behavior were observed among participants of the "Hi-Sleep-Lo-PA" and the "Lo-Sleep-Hi-PA" clusters.

CONCLUSIONS

It appeared that the combination of favorable circadian sleep patterns and high physical activity patterns was associated with lower aggressive behavior, lower self-injury and suicidal behavior as proxies of favorable psychological functioning. In contrast, persons reporting high circadian sleep disorders and low physical activity patterns appeared to demand particular attention and counseling for both their lifestyle issues (sleep and physical activity) and their dysfunctional coping strategies.

Sleep Debt Mediates the Relationship between Work-Related Social Factors, Presenteeism, and Well-Being in Japanese Workers

Sleep debt is associated with presenteeism and mental health; however, the association of sleep debt with presenteeism and well-being in the context of work-related social factors (commuting time, workdays, and working hours) has not been fully elucidated. This study aimed to examine whether work-related social factors are associated with presenteeism and well-being via sleep debt. The participant group comprised 872 full-time and 526 part-time workers (mean age: 44.65 ± 12.37 and 48.47 ± 12.93 years, respectively). For both the full-time and part-time workers, increased sleep debt was significantly associated with presenteeism (β = -0.171; β = -0.160) and low well-being (β = -0.135; β = -0.153). Notably, commuting time was significantly associated with increased sleep debt in full-time workers (β = 0.09). In contrast, the number of workdays was significantly associated with increased sleep debt in part-time workers (β = -0.102). Working hours were not significantly associated with sleep debt for both full- and part-time workers. These results reveal that sleep debt might lead to various risks among workers, elucidating the work-related social factors related to sleep debt. They also highlight the importance of considering work-related social factors when addressing sleep debt.

Understanding the Need for Sleep to Improve Cognition

The restorative function of sleep is shaped by its duration, timing, continuity, subjective quality, and efficiency. Current sleep recommendations specify only nocturnal duration and have been largely derived from sleep self-reports that can be imprecise and miss relevant details. Sleep duration, preferred timing, and ability to withstand sleep deprivation are heritable traits whose expression may change with age and affect the optimal sleep prescription for an individual. Prevailing societal norms and circumstances related to work and relationships interact to influence sleep opportunity and quality. The value of allocating time for sleep is revealed by the impact of its restriction on behavior, functional brain imaging, sleep macrostructure, and late-life cognition. Augmentation of sleep slow oscillations and spindles have been proposed for enhancing sleep quality, but they inconsistently achieve their goal. Crafting bespoke sleep recommendations could benefit from large-scale, longitudinal collection of objective sleep data integrated with behavioral and self-reported data.

A Random Forest approach to identify metrics that best predict match outcome and player ranking in the esport Rocket League

Notational analysis is a popular tool for understanding what constitutes optimal performance in traditional sports. However, this approach has been seldom used in esports. The popular esport "Rocket League" is an ideal candidate for notational analysis due to the availability of an online repository containing data from millions of matches. The purpose of this study was to use Random Forest models to identify in-match metrics that predicted match outcome (performance indicators or "PIs") and/or in-game player rank (rank indicators or "RIs"). We evaluated match data from 21,588 Rocket League matches involving players from four different ranks. Upon identifying goal difference (GD) as a suitable outcome measure for Rocket League match performance, Random Forest models were used alongside accompanying variable importance methods to identify metrics that were PIs or RIs. We found shots taken, shots conceded, saves made, and time spent goalside of the ball to be the most important PIs, and time spent at supersonic speed, time spent on the ground, shots conceded and time spent goalside of the ball to be the most important RIs. This work is the first to use Random Forest learning algorithms to highlight the most critical PIs and RIs in a prominent esport.

Physical Activity and Inhibitory Control: The Mediating Role of Sleep Quality and Sleep Efficiency

OBJECTIVES

the current study aimed to investigate the relationship between physical activity (PA) level and inhibitory control performance and then to determine whether this association was mediated by multiple sleep parameters (i.e., subjective sleep quality, sleep duration, sleep efficiency, and sleep disturbance).

METHODS

180 healthy university students (age: 20.15 ± 1.92 years) from the East China Normal University were recruited for the present study. PA level, sleep parameters, and inhibitory control performance were assessed using the International Physical Activity Questionnaire (IPAQ), the Pittsburgh Sleep Quality Index Scale (PSQI), and a Stroop test, respectively. The data were analyzed using structural equation modeling.

RESULTS

A higher level of PA was linked to better cognitive performance. Furthermore, higher subjective sleep quality and sleep efficiency were associated with better inhibitory control performance. The mediation analysis revealed that subjective sleep quality and sleep efficiency mediated the relationship between PA level and inhibitory control performance.

CONCLUSION

our results are in accordance with the literature and buttress the idea that a healthy lifestyle that involves a relatively high level of regular PA and adequate sleep patterns is beneficial for cognition (e.g., inhibitory control performance). Furthermore, our study adds to the literature that sleep quality and sleep efficiency mediates the relationship between PA and inhibitory control performance, expanding our knowledge in the field of exercise cognition.