The Cognitive Social Network in Dreams: Transitivity,Assortativity, and Giant Component Proportion Are Monotonic

For five individuals, a social network was constructed from a series of his or her dreams. Three important network measures were calculated for each network: transitivity, assortativity, and giant component proportion. These were monotonically related; over the five networks as transitivity increased, assortativity increased and giant component proportion decreased. The relations indicate that characters appear in dreams systematically. Systematicity likely arises from the dreamer's memory of people and their relations, which is from the dreamer's cognitive social network. But the dream social network is not a copy of the cognitive social network. Waking life social networks tend to have positive assortativity; that is, people tend to be connected to others with similar connectivity. Instead, in our sample of dream social networks assortativity is more often negative or near 0, as in online social networks. We show that if characters appear via a random walk, negative assortativity can result, particularly if the random walk is biased as suggested by remote associations.     

A comprehensive analysis of factors leading to speeding offenses among large-truck drivers

Much research has demonstrated that speeding is the most common offense among car drivers. However, few studies have focused on this offense among drivers of large trucks. This paper investigates the factors that lead to speeding offenses for drivers of large trucks in Taiwan. The study sample consisted of information for 2101 male large-truck drivers from a national survey in 2012. The results revealed that drivers’ daily working hours ranged from 2 to 15 h with a mean of 9.67 h, and that they worked for approximately 25.23 days – and rested only 4.77 days – per month. Among these observed drivers, 11.6% reported having at least one speeding offense over a one-year period. The results of a logistic regression model presented that the factors that influenced speeding offense were not related to job experience. Rather, the driver’s demographics (age and education), mental condition (sleep quality), and driving status (yearly distance driven and driving late at night) were significantly linked to speeding offenses.     

Differential effects of driver sleepiness and sleep inertia on driving behavior

ObjectivesDriver sleepiness is one of the major safety issues in conventional driving and sleep inertia emerges as a driver state in automated driving. The aim of the present study was to assess the differential impacts of sleepiness and sleep inertia on driving behavior.Method61 participants completed a 10-min manual driving task during an otherwise automated drive. They completed the task (a) under an alert state, (b) under a sleepy state, and (c) after EEG-confirmed sleep. Driving performance was assessed with the parameters lane-keeping, speed choice, and speed-keeping. The eye-blink-based sleepiness measure PERCLOS (the proportion of time with eyes closed) was compared for the three driver states.ResultsLane- and speed-keeping performance were impaired under the sleepy state and after sleep, relative to the alert state. After sleep, lane-keeping behavior recovered rapidly and speed-keeping recovered by trend. Under the sleepy state, performance deteriorated. After sleep, the mean speed was lower than in the sleepy state and in the alert state. PERCLOS was increased after sleep and under the sleepy state, relative to the alert state.ConclusionsAlthough sleep inertia had detrimental effects on driving parameters similar to sleepiness, this effect rapidly vanished. Hence, while brief naps might be suitable to restore alertness in general, the minimal time needed to regain full capacity after napping should be a focus of future research.     

Culture and the organization of infant sleep: A study in the Netherlands and the U.S.A.

This study investigates differences in the amount and structure of infant sleep in two cultural places with previously documented, divergent parental beliefs and practices. Eight-month-old infants (n = 24 per site) were recruited from towns in the Netherlands and the eastern U.S.A. To evaluate sleep, infants’ physical activity was recorded at home for 24 h using a miniature actigraph, while parents kept a diary of infant activities. Measures derived from actigraphy include total sleep, longest sleep episode, longest wake episode, number of sleep episodes, and percent of sleep during nighttime, as well as time in the stages of Quiet and Active Sleep. Measures based on the parental diaries include most of these aspects as well, except those related to sleep stages. Results based on the more precise actigraphy method indicate that (1) the Dutch infants averaged 13.65 h of sleep per 24 h, 1.67 h more than the U.S. infants; this difference was mostly due to daytime sleep; (2) The Dutch infants’ longest wake episode averaged less than that of the U.S. infants, while their longest sleep episode appeared slightly longer. (3) The Dutch infants, compared to the U.S. sample, spent more time in the Quiet, rather than the Active phase of sleep; (4) They began their Quiet sleep earlier in the evening than did their U.S. counterparts. Measures derived from parental diaries are largely in agreement with the actigraph findings. These results are consistent with reported and observed practices and beliefs in the two communities. The pattern of differences – less apparent maturity among the Dutch in the amount of sleep, but greater apparent maturity in the structure of sleep -- illustrates that behavioral and neurological maturity can be assessed only in the context of the developing child’s adaptation to the specific demands and affordances of the culturally structured developmental niche.     

Temperament and sleep behaviors in infants and toddlers living in low-income homes

Temperament is a dynamic trait that can be shaped by maturity and environmental experiences. In this study, we sought to determine whether and the extent to which temperament was predicted by sleeping behaviors in an understudied sample of primarily Black and White infants and toddlers living in low-income homes (N = 150). Sleeping behaviors were assessed at 15–19 months of age with caregiver report of the Tayside Children’s Sleep Questionnaire. Temperament was examined as effortful control, negativity, and surgency with the Infant Behavior Questionnaire Very Short Form at 9–12 months of age and with the Early Childhood Behavior Questionnaire Short Form at 20–24 months of age. Covariates were maternal education, household income, and child sex and race. Continuous variables were standardized, then missing data from independent variables were multiply imputed in 20 datasets. Regression analyses showed that about 1 SD improvement in toddler sleep behaviors significantly predicted about 1/5 SD better toddler effortful control. However, sleep behaviors did not significantly predict toddler surgency or negative affect. This study shows that for a sample of infants and toddlers in low-income homes, how a child learns to regulate sleeping behaviors may influence the development of overall effortful control about six months later.     

Sleep,resilience, and psychological distress in United States military Veterans

Sleep problems are prevalent among Veterans. Left untreated, such problems may elevate psychological distress and increase risk of subsequent mental health disorders. Psychological resilience may buffer against negative psychological outcomes, yet the relationship between sleep and resilience has not been studied. This study explored poor sleep, resilience, and psychological distress using questionnaires collected as part of the Study of Post-Deployment Mental Health. Participants (N = 1,118) had served in the US military since September 11, 2001, had one or more overseas deployments, and were free from a past-month DSM-defined mental health disorder. Hierarchical linear regression was used to examine the association between poor sleep quality (Pittsburgh Sleep Quality Index total score) and psychological distress (Global Symptom Index; Symptom Checklist-90-R), controlling for demographic and health characteristics. Moderation analyses tested for a potential buffering effect of resilience (Connor-Davidson Resilience Scale). Poor sleeping Veterans had worse physical and psychological health, lower resilience, and endorsed more lifetime traumatic events. Poor sleep was associated with greater psychological distress controlling for health and demographic characteristics. Both resilience factors—adaptability and self-efficacy—had significant buffering effects on the relationship between poor sleep and psychological distress, suggesting that resilience may protect against negative outcomes in poor sleepers. Additional research is warranted to better understand the relationships between sleep, resilience, and psychological distress. Such research may inform pertinent prevention efforts, including interventions that improve sleep, enhance resilience, and protect against incident mental health diagnoses.     

Increased conspiracy beliefs among ethnic and Muslim minorities

In the present study, we tested whether Muslim minority members are more susceptible to conspiracy theories than majority members in the Netherlands. We examined conspiracy theories that are relevant (portraying the Muslim community as victim or Jewish people as perpetrators) and irrelevant for participants' Muslim identity (about the 2007 financial crisis, and other theories such as that the moon landings were fake). Results revealed that Muslims believed both identity‐relevant and irrelevant conspiracy theories more strongly than non‐Muslims. These differences could not be attributed to the contents of Muslim faith: Ethnic minority status exerted similar effects independent of Muslim identity. Instead, evidence suggested that feelings of both personal and group‐based deprivation independently contribute to belief in conspiracy theories. We conclude that feelings of deprivation lead marginalized minority members to perceive the social and political system as rigged, stimulating belief in both identity‐relevant and irrelevant conspiracy theories.     

Sleep interventions for performance,mood and sleep outcomes in athletes: A systematic review and meta-analysis

Sleep is fundamental to sports performance and other health outcomes such as mental wellbeing. This systematic review explored the effects of sleep interventions implemented among athletes on performance, sleep, and mood outcomes. Five databases were searched, returning 5996 records for screening. Of these, 27 articles met the inclusion criteria (16 controlled deigns, 11 uncontrolled; athletes n = 617; male n = 432, female n = 93, non-binary/other n = 0 or not reported n = 92). Narrative synthesis of all studies based on intervention type suggested that sleep hygiene, assisted sleep, and sleep extension interventions may be associated with improved sleep, performance, and mood outcomes. Twelve controlled trials were eligible for quantitative meta-analysis, investigating the effect of sleep interventions on athlete sleep, performance, and negative affect, compared to controls post-intervention. Utilizing random-effects meta-analyses, sleep interventions improved subjective sleep quality (g = 0.62, 95% CI [0.21, 1.02]), reduced sleepiness (g = 0.81, 95% CI [0.32, 1.30]) and decreased negative affect (g = 0.63, 95% CI [0.27, 0.98]), but did not appear to influence subjective sleep duration. No effects were identified for objective sleep measures (e.g., actigraphy), or aerobic/anaerobic performance indices. While sleep interventions may offer some benefit to athletes, caution is warranted given limitations of the extant research relating to small, non-representative studies with methodological concerns.