Sleep restriction alters the integration of multiple information sources in probabilistic decision-making.

The detrimental effects of sleep loss on overall decision-making have been well described. Due to the complex nature of decisions, there remains a need for studies to identify specific mechanisms of decision-making vulnerable to sleep loss. Bayesian perspectives of decision-making posit judgement formation during decision-making occurs via a process of integrating knowledge gleaned from past experiences (priors) with new information from current observations (likelihoods). We investigated the effects of sleep loss on the ability to integrate multiple sources of information during decision-making by reporting results from two experiments: the first implementing both sleep restriction (SR) and total sleep deprivation (TSD) protocols, and the second implementing an SR protocol. In both experiments, participants were administered the Bayes Decisions Task on which optimal performance requires the integration of Bayesian prior and likelihood information. Participants in Experiment 1 showed reduced reliance on both information sources after SR, while no significant change was observed after TSD. Participants in Experiment 2 showed reduced reliance on likelihood after SR, especially during morning testing sessions. No accuracy-related impairments resulting from SR and TSD were observed in both experiments. Our findings show SR affects decision-making through altering the way individuals integrate available sources of information. Additionally, the ability to integrate information during SR may be influenced by time of day. Broadly, our findings carry implications for working professionals who are required to make high-stakes decisions on the job, yet consistently receive insufficient sleep due to work schedule demands.

Awareness of errors is reduced by sleep loss.

The ability to detect and subsequently correct errors is important in preventing the detrimental consequences of sleep loss. The Error Related Negativity (ERN), and the error positivity (Pe) are established neural correlates of error processing. Previous work has shown sleep loss reduces ERN and Pe, indicating sleep loss impairs error-monitoring processes. However, no previous work has examined behavioral error awareness, in conjunction with EEG measures, under sleep loss conditions, and studies of sleep restriction are lacking. Using combined behavioral and EEG measures, we report two studies investigating the impact of total sleep deprivation (TSD) and sleep restriction (SR) on error awareness. Fourteen healthy participants completed the Error Awareness Task under conditions of TSD and 27 completed the same task under conditions of SR. It was found that TSD did not influence behavioral error awareness or ERN or Pe amplitude, however, SR reduced behavioral error awareness, increased the time taken to detect errors, and reduced Pe amplitude. Findings indicate individuals who are chronically sleep restricted are at risk for reduced recognition of errors. Reduced error awareness may be one factor contributing to the increased accidents and injuries seen in contexts where sleep loss is prevalent.

The ability to self-monitor cognitive performance during 60 h total sleep deprivation and following 2 nights recovery sleep.

We aimed to investigate whether self-monitoring of performance is altered during 60 h of total sleep deprivation, following 2 nights of recovery sleep, and by task difficulty and/or subjective sleepiness. Forty adults (22 females, aged 19-39 years) underwent a 5-day protocol, with a well-rested day, 66 h total sleep deprivation (last test session at 60 h), and 2 nights of 8 h recovery sleep. An arithmetic task (MATH) with three difficulty levels assessed working memory. The Psychomotor Vigilance Task assessed sustained attention. Arithmetic accuracy and Psychomotor Vigilance Task median reaction time measured objective performance. Subjective performance was measured with self-reported accuracy and speed. Objective-subjective differences assessed self-monitoring ability. The performance on both tasks declined during total sleep deprivation and improved following recovery. During total sleep deprivation, participants accurately self-monitored performance on the Psychomotor Vigilance Task; however, they overestimated cognitive deficits on MATH, self-reporting performance as worse than actually observed. Following recovery, participants overestimated the extent of performance improvement on the Psychomotor Vigilance Task. Task difficulty influenced self-monitoring ability, with greater overestimation of performance deficits during total sleep deprivation as difficulty increased. Subjective sleepiness predicted subjective performance ratings at several time points, only for the Psychomotor Vigilance Task. The ability to self-monitor performance was impaired during total sleep deprivation for working memory and after recovery sleep for the Psychomotor Vigilance Task, but was otherwise accurate. The development of self-monitoring strategies, assessing both subjective perceptions of performance and subjective sleepiness, within operational contexts may help reduce the consequences of sleep-related impairments.

The relationship between sleep and appetitive conditioning: A systematic review and meta-analysis.

This systematic review and meta-analysis (PROSPERO registration animal/human studies: CRD42021234793/CRD42021234790) examined the relationship between sleep and appetitive conditioning. Inclusion criteria included: a) appetitive conditioning paradigm; b) measure of conditioning; c) sleep measurement and/or sleep loss; d) human and/etor non-human animal samples; and e) written in English. Searches of seven databases returned 3777 publications. The final sample consisted of 42 studies using primarily animal samples and involving food- and drug-related conditioning tasks. We found sleep loss disrupted appetitive conditioning of food rewards (p < 0.001) but potentiated appetitive conditioning of drug rewards (p < 0.001). Furthermore, sleep loss negatively impacted extinction learning irrespective of the reward type. Post-learning sleep was associated with increases in REM sleep (p = 0.02). Findings suggest sleep loss potentiates the impact of psychoactive substances in a manner likely to produce an increased risk of problematic substance use. In obese/overweight populations, sleep loss may be associated with deficits in the conditioning and extinction of reward-related behaviours. Further research should assess the relationship between sleep and appetitive conditioning in humans.

Cognitive fitness modulates gender differences in sleep and mental health among competitive athletes under chronic stress.

Objectives: Mental fitness is increasingly considered a key component of an athlete's competitive arsenal. Active domains of mental fitness include cognitive fitness, sleep, and mental health; and these domains can differ between men and women athletes. Our study investigated the associations of cognitive fitness and gender to sleep and mental health, and the interaction between cognitive fitness and gender on sleep and mental health, in competitive athletes during the COVID-19 pandemic. Methods: 82 athletes competing at levels from regional/state to international (49% women, M-age = 23.3 years) completed measures of self-control, intolerance of uncertainty, and impulsivity (together representing constructs of cognitive fitness), items about sleep (total sleep time, sleep latency, and mid-sleep time on free days) and a measure of mental health (depression, anxiety, and stress). Results: Women athletes reported lower self-control, higher intolerance of uncertainty, and higher positive urgency impulsivity compared with men athletes. Women reported sleeping later, but this gender difference disappeared after controlling for cognitive fitness. Women athletes-after controlling for cognitive fitness-reported higher depression, anxiety, and stress. Across genders, higher self-control was associated with lower depression, and lower intolerance of uncertainty was associated with lower anxiety. Higher sensation seeking was associated with lower depression and stress, and higher premeditation was associated with greater total sleep time and anxiety. Higher perseverance was associated with higher depression for men-but not women-athletes. Conclusion: Women athletes in our sample reported poorer cognitive fitness and mental health compared to men athletes. Most cognitive fitness factors protected competitive athletes under chronic stress, but some exposed them to poorer mental health. Future work should examine the sources of gender differences. Our findings suggest a need to develop tailored interventions aimed at improving athlete wellbeing, with a particular focus on women athletes.

Sleep Restriction Reduces Cognitive but Not Physical Motivation.

Purpose: Motivation is an important driver of behaviour, and several frameworks distinguish the willingness of individuals to invest cognitive versus physical effort to achieve a goal. One outstanding question is whether sleep loss lowers motivation within specific domains of effort, or has a global effect on motivation across multiple domains. Here, we investigated the effects of sleep restriction on the motivation to invest cognitive or physical effort in return for reward. Materials and Methods: 24 healthy young adults (11 females) completed an effort-based decision-making task over two laboratory sessions - once while sleep restricted (three consecutive nights with a three-hour sleep opportunity), and the other while fully rested (nine-hour sleep opportunity on each night). In an initial reinforcement phase, participants were trained to ceiling performance across six levels of effort on separate cognitively and physically demanding tasks. Then, in the critical decision-making phase, participants revealed their preference for how much cognitive or physical effort they would be willing to invest for reward. Results: Sleep restriction reduced the willingness to exert cognitive effort, but spared motivation in the physical domain. Furthermore, the reduction in cognitive motivation appeared to be a primary motivational deficit, which could not be attributed to differences in reward-likelihood of different levels of effort or the temporal structure of the task. Conclusion: The results suggest that sleep restriction has a selective effect on cognitive over physical motivation, which has significant implications for real-world settings in which individuals must maintain high levels of cognitive motivation in the face of chronic sleep loss.

The impact of sleep loss on performance monitoring and error-monitoring: A systematic review and meta-analysis.

Awareness of performance deficits and errors during sleep loss could be protective against the consequences of sleep deprivation, however, it is unclear whether sleep deprived individuals have insight into their performance. We conducted a systematic review and meta-analysis of the impact of sleep loss (sleep duration <6 h) on monitoring of performance and errors using Embase, MEDLINE, PsycINFO & Cochrane Central. We identified 28 studies, 11 of which were appropriate for meta-analysis. The systematic review indicated limited consensus regarding sleep loss impacts on performance monitoring, due to substantial differences in study methodology. However, participants typically demonstrated more conservative estimates of performance during sleep loss. Error-monitoring literature was more consistent, indicating an impairment in error-monitoring following sleep loss. Meta-analyses supported the findings of the systematic review. In terms of methodology, we found the performance monitoring literature is limited by an overreliance on correlational designs, which are likely confounded by response bias. The error-monitoring literature is limited by very few studies utilising behavioural measures to directly measure error-awareness. Future performance monitoring studies must employ methods which control for confounds such as bias, and error-monitoring studies must incorporate combined behavioural and ERP measures to better understand the impact of sleep loss on error-monitoring.

Vulnerability and resistance to sleep disruption by a partner: A study of bed-sharing couples.

OBJECTIVES: Methods for analyzing sleep as a dyadic behavior remain relatively unexplored. We aimed to (1) characterize how bedpartners influence each other's sleep, and (2) identify factors that predict sensitivity to wake transmission between bedpartners. DESIGN: Cross-sectional study. SETTING: Community members in Melbourne, Australia. PARTICIPANTS: Fifty-five couples without sleep disorders, aged 18-72 years. MEASUREMENTS: Participants completed the Morningness-Eveningness Questionnaire, reduced version. Habitual sleep/wake patterns were monitored for seven nights via actigraphy and sleep diary. Epoch-by-epoch sleep/wake concordances (shared sleep/wake minutes), number of transmissions received (number of awakenings immediately preceded by bedpartner wakefulness), percent transmissions received (percentage of total awakenings that were transmissions), transmissibility (percentage of all bedpartner awakenings transmitted), and percent minutes resistant to transmission (percentage of bedpartner's wake minutes that an individual slept), were calculated. Mixed-effects modeling assessed predictors of dyadic sleep. RESULTS: We described rates of sleep concordance (M = 66.8% ± 6.8%), wake concordance (M = 6.8% ± 3.1%), number of transmissions received (M = 6.0 ± 2.7), percent transmissions received (M = 18.9% ± 7.5%), transmissibility (M = 20.0% ± 6.2%), and percent minutes resistant (M = 52.1% ± 13.6%). Average couple-level percent transmissions received were highest and percent minutes resistant lowest in couples who had similar bedtime (within 30 minutes), compared to couples with greater differences in bedtime. CONCLUSIONS: Wake transmission is a useful metric of dyadic sleep, which varies according to relative bedtimes, and chronotypes of bedpartners. Higher wake transmissions for couples with similar bedtimes suggest dyadic preferences for shared bedtimes may be due to psychosocial benefits of shared sleep timing, rather than minimization of bedpartner-driven sleep disruption.