Bifidobacterium longum 1714 improves sleep quality and aspects of well-being in healthy adults: a randomized, double-blind, placebo-controlled clinical trial.

Stress and sleep are linked with overall well-being. Bifidobacterium longum 1714 has been shown to influence stress responses and modulate neural responses during social stress, and influence sleep quality during examination stress in healthy adults. Here, we explored the ability of this strain to alter sleep quality in adults using subjective and objective measures. Eighty-nine adults (18-45y) with impaired sleep quality assessed with the Pittsburgh Sleep Quality Index (PSQI) and with a global score ≥ 5 were randomized to receive B. longum 1714 or placebo daily for eight weeks. Assessing the effect of the strain on PSQI global score was the primary objective. Secondary objectives assessed sleep quality and well-being subjectively and sleep parameters using actigraphy objectively. While PSQI global score improved in both groups, B. longum 1714 significantly improved the PSQI component of sleep quality (p < 0.05) and daytime dysfunction due to sleepiness (p < 0.05) after 4 weeks and social functioning (p < 0.05) and energy/vitality (p < 0.05) after 8 weeks, compared to placebo. No significant effect on actigraphy measures were observed. The 1714 strain had a mild effect on sleep, demonstrated by a faster improvement in sleep quality at week 4 compared to placebo, although overall improvements after 8 weeks were similar in both groups. B. longum 1714 improved social functioning and increased energy/vitality in line with previous work that showed the strain modulated neural activity which correlated with enhanced vitality/reduced mental fatigue (ClinicalTrials.gov: NCT04167475).

Social Deprivation and Ethnicity Are Associated with More Problematic Sleep in Middle-Aged and Older Adults.

Objectives: We test the hypothesis that the incidence of sleep problems is influenced by socio-demographic variables, particularly social deprivation and ethnicity. Methods: Self-reports of sleep duration and sleep difficulties (waking in the night, sleeping in the day, difficulty waking and snoring), personal wealth (household income, property-owning, etc.), ethnic group, employment, education, as well as post-code-based Townsend Social Deprivation, were extracted from UK Biobank's cohort of c500,000 British-domiciled adults (40-70 years). Analyses contrasted the incidence of different sleep problems and a composite measure of these (the Problematic Sleep Index) across groups. Results: Almost one-third of participants reported sleeping shorter (24.7%), or longer (7.7%) than age-corrected recommended sleep durations. The incidence of shorter or longer sleep increased with social deprivation and varied with ethnicity. Snoring, waking during the night, finding it difficult to get up in the morning and sleeping in the daytime were subject to similar effects. The Problematic Sleep Index showed being younger, male, employed, home-owning, having a higher household income, having a higher level of educational achievement, and time in education were all associated with better sleep, as was living in a more affluent area and being White. Conclusions: Sleep problems in Britain show a social gradient, independently of a range of other demographic and social influences, suggesting that sleep quality differs with and between ethnic groups. These sleep inequalities suggest that the protective and recuperative effects of sleep are disproportionately distributed across society and should encourage us to consider the potential benefits of community-specific sleep interventions.

Early-Life Exposure to PM2.5 and Sleep Disturbances in Preschoolers from 551 Cities of China.

Rationale: Air pollution has been linked with sleep disturbance in adults, but the association in children remains unclear. Objectives: To examine the associations of prenatal and postnatal exposure to fine particulate matter (particulate matter ⩽2.5 µm in aerodynamic diameter; PM2.5) with sleep quality and sleep disturbances among children in 551 Chinese cities. Methods: A total of 1,15,023 children aged 3-7 years from the Chinese National Cohort of Motor Development were included. Sleep quality was measured using the Children's Sleep Habits Questionnaire (CSHQ). PM2.5 exposure was estimated using a satellite-based model. Generalized additive mixed models with Gaussian and binomial distributions were used to examine the associations of PM2.5 exposure with CSHQ scores and risk of sleep disturbance, respectively, adjusting for demographic characteristics and temporal trends. Measurements and Main Results: Early-life PM2.5 exposure was associated with higher total CSHQ score, and the association was stronger for exposure at age 0-3 years (change of CSHQ score per interquartile range increase of PM2.5 = 0.46; 95% confidence interval [CI], 0.29-0.63) than during pregnancy (0.22; 95% CI, 0.12-0.32). The associations were more evident in sleep-disordered breathing and daytime sleepiness. Postnatal PM2.5 exposure was associated with increased risk of sleep disturbance (adjusted odds ratio for per-interquartile range increase of PM2.5 exposure at age 0-3 years, 1.10; 95% CI, 1.04-1.15), but no associations were found for prenatal exposure. Children who were exclusively breastfed for <6 months and had neonatal ICU admission may be more vulnerable to sleep disturbance related to PM2.5 exposure. Conclusions: PM2.5 exposure can impair sleep quality in preschool children.

Contrasting Effects of Sleep Restriction, Total Sleep Deprivation, and Sleep Timing on Positive and Negative Affect.

Laboratory-based sleep manipulations show asymmetries between positive and negative affect, but say little about how more specific moods might change. We report extensive analyzes of items from the Positive and Negative Affect Scale (PANAS) during days following nights of chronic sleep restriction (6 h sleep opportunity), during 40 h of acute sleep deprivation under constant routine conditions, and during a week-long forced desynchrony protocol in which participants lived on a 28-h day. Living in the laboratory resulted in medium effects sizes on all positive moods (Attentiveness, General Positive Affect, Joviality, Assuredness), with a general deterioration as the days wore on. These effects were not found with negative moods. Sleep restriction reduced some positive moods, particularly Attentiveness (also General Positive), and increased Hostility. A burden of chronic sleep loss also led to lower positive moods when participants confronted the acute sleep loss challenge, and all positive moods, as well as Fearfulness, General Negative Affect and Hostility were affected. Sleeping at atypical circadian phases resulted in mood changes: all positive moods reduced, Hostility and General Negative Affect increased. Deteriorations increased the further participants slept from their typical nocturnal sleep. In most cases the changes induced by chronic or acute sleep loss or mistimed sleep waxed or waned across the waking day, with linear or various non-linear trends best fitting these time-awake-based changes. While extended laboratory stays do not emulate the fluctuating emotional demands of everyday living, these findings demonstrate that even in controlled settings mood changes systematically as sleep is shortened or mistimed.

Associations between gestational age and childhood sleep: a national retrospective cohort study.

BACKGROUND: Both sleep quality and quantity are essential for normal brain development throughout childhood; however, the association between preterm birth and sleep problems in preschoolers is not yet clear, and the effects of gestational age across the full range from preterm to post-term have not been examined. Our study investigated the sleep outcomes of children born at very-preterm (<31 weeks), moderate-preterm (32-33 weeks), late-preterm (34-36 weeks), early-term (37-38 weeks), full-term (39-40 weeks), late-term (41 weeks) and post-term (>41 weeks). METHODS: A national retrospective cohort study was conducted with 114,311 children aged 3-5 years old in China. Children's daily sleep hours and pediatric sleep disorders defined by the Children's Sleep Habits Questionnaire (CSHQ) were reported by parents. Linear regressions and logistic regression models were applied to examine gestational age at birth with the sleep outcomes of children. RESULTS: Compared with full-term children, a significantly higher CSHQ score, and hence worse sleep, was observed in very-preterm (ß = 1.827), moderate-preterm (ß = 1.409), late-preterm (ß = 0.832), early-term (ß = 0.233) and post-term (ß = 0.831) children, all p<0.001. The association of pediatric sleep disorder (i.e. CSHQ scores>41) was also seen in very-preterm (adjusted odds ratio [AOR] = 1.287 95% confidence interval [CI] (1.157, 1.433)), moderate-preterm (AOR = 1.249 95% CI (1.110, 1.405)), late-preterm (AOR = 1.111 95% CI (1.052, 1.174)) and post-term (AOR = 1.139 95% CI (1.061, 1.222)), all p<0.001. Shorter sleep duration was also found in very-preterm (ß = -0.303), moderate-preterm (ß = -0.282), late-preterm (ß = -0.201), early-term (ß = -0.068) and post-term (ß = -0.110) compared with full-term children, all p<0.01. Preterm and post-term-born children had different sleep profiles as suggested by subscales of the CSHQ. CONCLUSIONS: Every degree of premature, early-term and post-term birth, compared to full-term, has an association with sleep disorders and shortened daily sleep duration. Preterm, early-term, and post-term should therefore all be monitored with an increased threat of sleep disorder that requires long-term monitoring for adverse sleep outcomes in preschoolers.

Examining the role of systemic chronic inflammation in diet and sleep relationship.

BACKGROUND: It is well known that systemic chronic inflammation (SCI), which can be modulated by diet, is associated with poor sleep outcomes. However, the role of SCI in diet health and sleep quality relationship has not been well established. METHODS: Here, by using the UK Biobank data set, we assessed the association between markers of SCI (leukocyte, platelet, lymphocyte, neutrophil, and basophil counts; C-reactive protein levels and neutrophil to lymphocyte ratio (NLR)), habitual intake of food groups, diet health and sleep quality in 449,084 participants. We also formally tested the possibility that SCI might mediate the relationship between diet health and sleep quality. RESULTS: Our results revealed (i) negative associations between SCI and food groups that are abundant in healthy diets (fruit, vegetable and oily and non-oily fish) and (ii) positive associations between SCI and food groups that are abundant in unhealthy diets (processed meat). Sleep quality was also negatively associated with platelet counts, CRP levels and NLR. Crucially, however, while platelet and neutrophil counts, CRP levels and NLR fully mediated the association between diet health and sleep quality, leukocyte, lymphocyte and basophil counts partially mediated the associations between diet health and sleep quality. CONCLUSION: Reducing SCI via dietary interventions could be an effective primary and/or complementary strategy to increase sleep quality. Further interventional trials are warranted to (i) establish the strength of associations, preferably by using validated diet and sleep measures and (ii) examine longer term effects of anti-inflammatory diets on sleep-, diet- and inflammation-related health outcomes.

Driving and cognitive function in people with stroke and healthy age-matched controls.

The decision to return to driving is both complex and difficult. It is often made with clinician support, perhaps on the basis of results from standardized paper and pencil tests, and less frequently an assessment of on-road driving. However, the resources required and inherent reliability and validity challenges suggest that greater use of computerization and driving simulation may play a useful role in the assessment process. In this study, thirty-six age-matched healthy and post-stroke drivers completed standard psychometric assessments (including NART, MMSE, BADS, IADL), computer delivered cognitive assessments (including SART, N-Back, Simple Reaction Time), as well as simulated and on-road assessments of driving. While significantly different in terms of psychometric and computer-based assessments, the healthy and post-stroke drivers who completed the on-road test did not differ. In contrast, driving in the portable simulator showed impaired driving, on some but not all driving manoeuvres, for those who failed the on-road test or had voluntarily ceased to drive. These results are discussed in terms of the implications they have for the multi-faceted nature of driving as a skill, and the need to involve simulation when assessing fitness to drive.

Diet, Sleep, and Mental Health: Insights from the UK Biobank Study.

Diet has long been the focus of attention as a leading risk factor for non-communicable diseases. As such, a better understanding of it is crucial to establish priorities for dietary guidelines and to inform, design, and implement strategies for preventing, helping manage, and stopping the progression of sleep and mental health-related symptoms/disorders. The aim of the current study is to conduct the largest investigation of diet, sleep, and mental health to date by utilizing the UK Biobank (UKB) dataset to identify the associations between diet and (i) sleep quality/health, and (ii) mental health symptomatology. This cross-sectional population-based study involved 502,494 middle-aged adults. UKB food frequency, sleep, and psychological factors and mental health questionnaires at baseline were used. Scores were also calculated for healthy diet, healthy sleep, mental health symptomatology, partial fibre intake, and milk intake. We observed positive associations with healthy diet and sleep and mental health, especially benefits of high intakes of vegetable, fruit, fish, water, and fibre. However, processed meat and milk intake were adversely associated with sleep and mental health. These findings make clear that there are health and wellbeing benefits and drawbacks of different diets, but do not, at this stage, demonstrate the clear causal relationships, which would support dietary interventions that might play a role in the treatment and also self-management of sleep and mental health disorders/symptoms. Further research is required to understand mechanisms of actions of which diet acts on to modulate sleep and mental health, while taking comorbidity of sleep and mental health disorders/symptoms into consideration.

Diet and general cognitive ability in the UK Biobank dataset.

Accumulating evidence suggests that dietary interventions might have potential to be used as a strategy to protect against age-related cognitive decline and neurodegeneration, as there are associations between some nutrients, food groups, dietary patterns, and some domains of cognition. In this study, we aimed to conduct the largest investigation of diet and cognition to date, through systematically examining the UK Biobank (UKB) data to find out whether dietary quality and food groups play a role on general cognitive ability. This cross-sectional population-based study involved 48,749 participants. UKB data on food frequency questionnaire and cognitive function were used. Also, healthy diet, partial fibre intake, and milk intake scores were calculated. Adjusted models included age, sex, and BMI. We observed associations between better general cognitive ability and higher intakes of fish, and unprocessed red meat; and moderate intakes of fibre, and milk. Surprisingly, we found that diet quality, vegetable intake, high and low fibre and milk intake were inversely associated with general cognitive ability. Our results suggest that fish and unprocessed red meat and/or nutrients that are found in fish and unprocessed red meat might be beneficial for general cognitive ability. However, results should be interpreted in caution as the same food groups may affect other domains of cognition or mental health differently. These discrepancies in the current state of evidence invites further research to examine domain-specific effects of dietary patterns/food groups on a wide range of cognitive and affective outcomes with a special focus on potential covariates that may have an impact on diet and cognition relationship.

Self-reported sleep quality is more closely associated with mental and physical health than chronotype and sleep duration in young adults: A multi-instrument analysis.

Sleep and circadian rhythms are considered to be important determinants of mental and physical health. Epidemiological studies have established the contribution of self-reported sleep duration, sleep quality and chronotype to health outcomes. Mental health and sleep problems are more common in women and men are more likely to be evening types. Few studies have compared the relative strength of these contributions and few studies have assessed these contributions separately in men and women. Furthermore, sleep and circadian characteristics are typically assessed with a limited number of instruments and a narrow range of variables is considered, leaving the understanding of the relative contribution of different predictors somewhat fractionary. We compared sleep quality, sleep duration and chronotype as predictors for self-reported mental and physical health and psychological characteristics in 410 men and 261 women aged 18 to 30. To ascertain that results were not dependent on the use of specific instruments we used a multitude of validated instruments including the Morningness-Eveningness-Questionnaire, Munich-ChronoType-Questionnaire, Pittsburgh-Sleep-Quality-Index, British-Sleep-Survey, Karolinska-Sleep-Diary, Insomnia-Severity-Index, SF-36-Health Survey, General-Health-Questionnaire, Dutch-Eating-Behaviour-Questionnaire, Big-Five-Inventory, Behaviour-Inhibition-System-Behaviour-Activation-System, and the Positive-Affect-Negative-Affect-Schedule. Relative contributions of predictors were quantified as local effect sizes derived from multiple regression models. Across all questionnaires, sleep quality was the strongest independent predictor of health and in particular mental health and more so in women than in men. The effect of sleep duration and social jetlag was inconspicuous. A greater insight into the independent contributions of sleep quality and chronotype may aid the understanding of sleep-health interactions in women and men.

Effects of Oral Gamma-Aminobutyric Acid (GABA) Administration on Stress and Sleep in Humans: A Systematic Review.

Gamma-aminobutyric acid (GABA) is a non-proteinogenic amino acid and is the main inhibitory neurotransmitter in the mammalian brain. GABA's stress-reducing, and sleep enhancing effects have been established. However, although several human clinical trials have been conducted, results regarding the role of natural and/or biosynthetic oral GABA intake on stress and sleep are mixed. We performed a systematic review to examine whether natural and/or biosynthetic oral GABA intake has an effect on stress and sleep. We systematically searched on PubMed database for studies published up to February 2020 following PRISMA guidelines. Only placebo-controlled human trials that assessed stress, sleep, and related psychophysiological outcomes as a response to natural GABA (i.e., GABA that is present naturally in foods) or biosynthetic GABA (i.e., GABA that is produced via fermentation) intake were included. Fourteen studies met the criteria and were included in the systematic review. Although more studies are needed before any inferences can be made about the efficacy of oral GABA consumption on stress and sleep, results show that there is limited evidence for stress and very limited evidence for sleep benefits of oral GABA intake.

Driver performance under simulated and actual driving conditions: Validity and orthogonality.

This study contrasted the performance of drivers under actual and simulated driving conditions, in order to assess the validity of the simulators and test the hypothesis that driving is composed of largely orthogonal sub-tasks. Thirty experienced drivers completed an on-road driving test and drove two different simulators, each simulator drive comprising seven difficulty-moderated driving scenarios. Between-simulator contrasts revealed largely absolute validity, the anticipated effects of increased difficulty within driving scenarios, but weak relationships between performance of different driving scenarios. On-road driving was reliably assessed by a nationally-recognised expert driving assessor, as reflected by standard statistical measures of reliability and consistency. However, on-road driving revealed relatively little cross-category correlation of on-road driving errors, or between on-road and simulator driving. Thus, despite the compelling evidence of absolute and relative validity within and between simulators, there is little evidence of criterion validity (i.e. relationship to on road driving, as assessed by the expert assessor). Moreover, the study provides strong evidence for orthogonality in the driving task- driving comprises large numbers of relatively separate tasks.

Impaired cognitive function in Crohn's disease: Relationship to disease activity.

BACKGROUND & AIMS: Impaired attention and response inhibition have been reported in patients with Crohn's disease (CD) in clinical remission. Prospective studies are needed to determine whether this is a stable feature of CD and whether a similar impairment is evident in ulcerative colitis (UC). Thus, our aims were to examine whether patients with CD and UC exhibited a persistent impairment in attentional performance, and if this impairment was related to key biological indices of relevance to cognition. METHODS: A prospective observational study was conducted on fifteen patients with CD and 7 with UC in clinical remission recruited from a specialty clinic and 30 healthy matched control participants. A neuropsychological assessment was carried out at baseline (visit 1) and at a 6 month follow-up (visit 2). Plasma proinflammatory cytokines, the plasma kynurenine:tryptophan (Kyn:Trp) ratio and the salivary cortisol awakening response (CAR) were also determined at each visit. RESULTS: Across visits, patients with CD exhibited impaired attentional performance (p â€‹= 0.023). Plasma IL-6 (P â€‹= â€‹0.001) and the Kyn:Trp ratio (P â€‹= â€‹0.03) were consistently elevated and the CAR significantly blunted (P â€‹< â€‹0.05) in patients with CD. No significant relationships were identified between any biochemical parameter and altered cognitive performance. CONCLUSIONS: Impaired cognitive function is a stable feature of patients with CD. These data suggest that even where remission has been achieved, the functional impact of an organic gastrointestinal disorder on cognition is still evident. However, it is unclear at present if physiological changes due to disease activity play a role in cognitive impairment in CD.

Longitudinal associations between family identification, loneliness, depression, and sleep quality.

OBJECTIVES: The prevalence of depression and loneliness is increasing in Western nations, and both have been shown to cause poor sleep quality, with evidence suggesting that loneliness also predicts depression. The Social Cure perspective can shed light on these relationships and thus informs the present study. Specifically, it was hypothesized that the extent of participants' identification with a significant social group, their family, would positively predict sleep quality and that this relationship would be mediated by loneliness and depression. DESIGN: A two-lave longitudinal online survey was used. METHODS: Participants completed an online survey at T1 (N = 387) and 1 year later at T2 (N = 122) assessing the extent to which they identified with their family. Their loneliness, depressive symptomology, and sleep quality/insomnia severity were also measured. RESULTS: Consistent with predictions, cross-sectional and longitudinal serial mediation models indicated that family identification was a negative predictor of loneliness, which in turn was a positive predictor of depression, which predicted poor sleep quality/insomnia. CONCLUSIONS: This is the first Social Cure study to explore the mediated relationship between social identification and sleep quality. As well as advancing the Social Cure perspective, these results have implications for how health professionals understand, prevent, and treat sleep problems. Statement of contribution What is already known on this subject? The prevalence of depression and loneliness is increasing in Western nations, and both have been shown to cause poor sleep quality. Weak social networks have been shown to predict restless sleep over time, and that depressed mood mediates this relationship. What does this study add? Family identification negatively predicted poor sleep quality cross-sectionally. Depression and loneliness positively predicted poor sleep quality over time. Depression and loneliness mediated the family identification-sleep quality relationship over time.

Rapid Eye Movement Sleep, Sleep Continuity and Slow Wave Sleep as Predictors of Cognition, Mood, and Subjective Sleep Quality in Healthy Men and Women, Aged 20-84 Years.

Sleep and its sub-states are assumed to be important for brain function across the lifespan but which aspects of sleep associate with various aspects of cognition, mood and self-reported sleep quality has not yet been established in detail. Sleep was quantified by polysomnography, quantitative Electroencephalogram (EEG) analysis and self-report in 206 healthy men and women, aged 20-84 years, without sleep complaints. Waking brain function was quantified by five assessments scheduled across the day covering objectively assessed performance across cognitive domains including sustained attention and arousal, decision and response time, motor and sequence control, working memory, and executive function as well as self-reports of alertness, mood and affect. Controlled for age and sex, self-reported sleep quality was negatively associated with number of awakenings and positively associated with the duration of Rapid Eye Movement (REM) sleep, but no significant associations with Slow Wave Sleep (SWS) measures were observed. Controlling only for age showed that associations between objective and subjective sleep quality were much stronger in women than in men. Analysis of 51 performance measures demonstrated that, after controlling for age and sex, fewer awakenings and more REM sleep were associated significantly with better performance on the Goal Neglect task, which is a test of executive function. Factor analysis of the individual performance measures identified four latent variables labeled Mood/Arousal, Response Time, Accuracy, and Visual Perceptual Sensitivity. Whereas Mood/Arousal improved with age, Response Times became slower, while Accuracy and Visual perceptual sensitivity showed little change with age. After controlling for sex and age, nominally significant association between sleep and factor scores were observed such that Response Times were faster with more SWS, and Accuracy was reduced where individuals woke more often or had less REM sleep. These data identify a positive contribution of SWS to processing speed and in particular highlight the importance of sleep continuity and REM sleep for subjective sleep quality and performance accuracy across the adult lifespan. These findings warrant further investigation of the contribution of sleep continuity and REM sleep to brain function.

Prospective memory while driving: comparison of time- and event-based intentions.

Prospective memories can divert attentional resources from ongoing activities. However, it is unclear whether these effects and the theoretical accounts that seek to explain them will generalise to a complex real-world task such as driving. Twenty-four participants drove two simulated routes while maintaining a fixed headway with a lead vehicle. Drivers were given either event-based (e.g. arriving at a filling station) or time-based errands (e.g. on-board clock shows 3:30). In contrast to the predominant view in the literature which suggests time-based tasks are more demanding, drivers given event-based errands showed greater difficulty in mirroring lead vehicle speed changes compared to the time-based group. Results suggest that common everyday secondary tasks, such as scouting the roadside for a bank, may have a detrimental impact on driving performance. The additional finding that this cost was only evident with the event-based task highlights a potential area of both theoretical and practical interest. Practitioner Summary: Drivers were given either time- or event-based errands whilst engaged in a simulated drive. We examined the effect of errands on an ongoing vehicle follow task. In contrast to previous non-driving studies, event-based errands are more disruptive. Common everyday errands may have a detrimental impact on driving performance.

Sex differences in the circadian regulation of sleep and waking cognition in humans.

The sleep-wake cycle and circadian rhythmicity both contribute to brain function, but whether this contribution differs between men and women and how it varies across cognitive domains and subjective dimensions has not been established. We examined the circadian and sleep-wake-dependent regulation of cognition in 16 men and 18 women in a forced desynchrony protocol and quantified the separate contributions of circadian phase, prior sleep, and elapsed time awake on cognition and sleep. The largest circadian effects were observed for reported sleepiness, mood, and reported effort; the effects on working memory and temporal processing were smaller. Although these effects were seen in both men and women, there were quantitative differences. The amplitude of the circadian modulation was larger in women in 11 of 39 performance measures so that their performance was more impaired in the early morning hours. Principal components analysis of the performance measures yielded three factors, accuracy, effort, and speed, which reflect core performance characteristics in a range of cognitive tasks and therefore are likely to be important for everyday performance. The largest circadian modulation was observed for effort, whereas accuracy exhibited the largest sex difference in circadian modulation. The sex differences in the circadian modulation of cognition could not be explained by sex differences in the circadian amplitude of plasma melatonin and electroencephalographic slow-wave activity. These data establish the impact of circadian rhythmicity and sex on waking cognition and have implications for understanding the regulation of brain function, cognition, and affect in shift-work, jetlag, and aging.

Self-reported sleep duration and cognitive performance in older adults: a systematic review and meta-analysis.

Sleep is important for optimal cognitive functioning across the lifespan. Among older adults (≥55 years), self-reported short and long sleep durations have been repeatedly, albeit inconsistently, reported to elevate the risk for poor cognitive function. This meta-analytic review quantitatively summarizes the risk for poorer cognitive function among short and long sleepers in older adults. Eligible publications were searched online and manually. A total of 35 independent samples (N = 97,264) from 11 cross-sectional and seven prospective cohort studies were included. Pooled odds ratios (OR) with 95% confidence intervals (CI) were derived using random-effects models. Self-reported short and long sleep increased the odds for poor cognitive function by 1.40 (CI = 1.27-1.56) and 1.58 times (CI = 1.43-1.74), respectively. Effect sizes varied across studies and may have been moderated by both study type (cross-sectional and prospective) and cognitive domain assessed. For cross-sectional studies, extreme sleep durations were significantly associated with poorer multiple-domain performance, executive functions, verbal memory, and working memory capacity. Prospective cohort studies revealed the significant long-term impact of short and long sleep on multiple-domain performance only. These findings establish self-reported extreme sleep duration as a risk factor for cognitive aging.

Twenty years of load theory-Where are we now, and where should we go next?

Selective attention allows us to ignore what is task-irrelevant and focus on what is task-relevant. The cognitive and neural mechanisms that underlie this process are key topics of investigation in cognitive psychology. One of the more prominent theories of attention is perceptual load theory, which suggests that the efficiency of selective attention is dependent on both perceptual and cognitive load. It is now more than 20 years since the proposal of load theory, and it is a good time to evaluate the evidence in support of this influential model. The present article supplements and extends previous reviews (Lavie, Trends in Cognitive Sciences, 9, 75-82. doi: 10.1016/j.tics.2004.12.004 , 2005, Current Directions in Psychological Science, 19, 143-148. doi: 10.1177/0963721410370295 , 2010) by examining more recent research in what appears to be a rapidly expanding area. The article comprises five parts, examining (1) evidence for the effects of perceptual load on attention, (2) cognitive load, (3) individual differences under load, (4) alternative theories and criticisms, and (5) the future of load theory. We argue that the key next step for load theory will be the application of the model to real-world tasks. The potential benefits of applied attention research are numerous, and there is tentative evidence that applied research would provide strong support for the theory itself, as well as real-world benefits related to activities in which attention is crucial, such as driving and education.

Identifying psychological and socio-economic factors affecting motorcycle helmet use.

Sixty percent of motorcyclist fatalities in traffic accidents of Iran are due to head injuries, but helmet use is low, despite it being a legal requirement. This study used face-to-face interviews to investigate the factors associated with helmet use among motorcycle riders in Mashhad city, the second largest city in Iran. Principal component analysis (PCA) and confirmatory factor analysis (CFA) were used for data reduction and identification of consistent features of the data. Ordered and multinomial logit analyses were used to quantify the influences on helmet use and non-use. The data show that 47% of the sample used a helmet, but a substantial proportion of these did not wear their helmet properly. In addition, 5% of motorcyclists believed that helmets reduced their safety. Norms, attitudes toward helmet use, risky traffic behavior and awareness of traffic rules were found to be the key determinants of helmet use, but perceptions of enforcement lacked influence. Duration of daily motorcycle trips, riding experience and type of job also affected helmet use. Results indicate that motorcyclist training, safety courses for offending motorcyclists and social programs to improve social norms and attitudes regarding helmet use are warranted, as are more effective law enforcement techniques, in order to increase proper use of helmets in Iranian motorcyclists. In addition, special safety courses should be considered for motorcyclists who have committed traffic violations.