Linking genetic foundations of sleep disturbances to personality traits: a study of mid-life twins.

Risk of sleep disturbances depends on individuals' personality, and a large body of evidence indicates that individuals prone to neuroticism, impulsivity, and (low) extraversion are more likely to experience them. Origins of these associations are unclear, but common genetic background may play an important role. Participants included 405 twin pairs (mean age of 54 years; 59% female) from the National Survey of Midlife Development in the United States (MIDUS) who reported on their personality traits (broad and specific), as well as sleep disturbances (problems with falling asleep, staying asleep, waking early, and feeling unrested). Uni- and bivariate biometric decompositions evaluated contributions of genetic and environmental factors to associations between personality and poor sleep, as well as unique contributions from individual traits. Neuroticism, extraversion, conscientiousness, and aggressiveness were the strongest phenotypic predictors of poor sleep. Genetic sources of covariance were about twice as large as non-shared environmental sources, and only shared genetic background accounted for links between aggressiveness and poor sleep. Neuroticism and extraversion accounted for most of the genetic overlap between personality and sleep disturbances. The findings shed light on developmental antecedents of ties between personality and poor sleep, suggesting a larger role of common genetic background than idiosyncratic life experiences. The results also suggest that emotion-related traits play the most important role for poor sleep, compared to other personality traits, and may partially account for genetic associations with other traits.

Sleepiness and Behavioral Risk-Taking: Do Sleepy People Take More or Less Risk?

BACKGROUND: Although sleep loss has been implicated in risk-taking behavior, it is unclear how individuals' current propensity to fall asleep, known as sleepiness, influences risk-taking. Because sleepiness is not only driven by recent sleep but also by factors such as circadian rhythm and current stimulation, it may be an important contributor to risk-taking as it reflects the more immediate sleep-wake state. PARTICIPANTS: One hundred thirty participants were recruited from a large Midwestern U.S. university. METHODS: Participants completed a short personality survey, reported their current sleepiness on the Stanford Sleepiness Scale, and then completed the Balloon Analog Risk Task, a computerized risk-taking measure in which participants earned real money for their performance. RESULTS: There was little support for a linear relation between sleepiness and risk-taking, but the evidence indicated a robust curvilinear relation. Even after controlling for important individual differences in sleep and risk-taking, participants who were moderately sleepy took longer to complete the risk-taking task, pumped balloons more, and exploded more balloons than those who were either low or high on sleepiness. CONCLUSIONS: The curvilinear relation between sleepiness and risk-taking sheds light on inconsistencies in prior findings linking sleepiness and sleep loss to risk-taking behavior. Moreover, current sleepiness appears to have unique implications for risk-taking.

The Narcissism Spectrum Model: A Synthetic View of Narcissistic Personality.

The narcissism spectrum model synthesizes extensive personality, social-psychological, and clinical evidence, building on existing knowledge about narcissistic grandiosity and vulnerability to reveal a view of narcissism that respects its clinical origins, embraces the diversity and complexity of its expression, and reflects extensive scientific evidence about the continuity between normal and abnormal personality expression. Critically, the proposed model addresses three key, inter-related problems that have plagued narcissism scholarship for more than a century. These problems can be summarized as follows: (a) What are the key features of narcissism? (b) How are they organized and related to each other? and (c) Why are they organized that way, that is, what accounts for their relationships? By conceptualizing narcissistic traits as manifested in transactional processes between individuals and their social environments, the model enables integration of existing theories of narcissism and thus provides a compelling perspective for future examination of narcissism and its developmental pathways.

Individual Differences in Diurnal Preference and Time-of-Exercise Interact to Predict Exercise Frequency.

BACKGROUND: Diurnal preference (and chronotype more generally) has been implicated in exercise behavior, but this relation has not been examined using objective exercise measurements nor have potential psychosocial mediators been examined. Furthermore, time-of-day often moderates diurnal preference's influence on outcomes, and it is unknown whether time-of-exercise may influence the relation between chronotype and exercise frequency. PURPOSE: The current study examined whether individual differences in diurnal preference ("morningness-eveningness") predict unique variance in exercise frequency and if commonly studied psychosocial variables mediate this relation (i.e., behavioral intentions, internal exercise control, external exercise control, and conscientiousness). Moreover, the study sought to test whether individuals' typical time-of-exercise moderated the impact of diurnal preference on exercise frequency. METHODS: One hundred twelve healthy adults (mean age = 25.4; SD = 11.6 years) completed baseline demographics and then wore Fitbit Zips® for 4 weeks to objectively measure exercise frequency and typical time-of-exercise. At the end of the study, participants also self-reported recent exercise. RESULTS: Diurnal preference predicted both self-reported exercise and Fitbit-recorded exercise frequency. When evaluating mediators, only conscientiousness emerged as a partial mediator of the relation between diurnal preference and self-reported exercise. In addition, time-of-exercise moderated diurnal preference's relation to both self-reported exercise and Fitbit-recorded exercise frequency such that diurnal preference predicted higher exercise frequency when exercise occurred at a time that was congruent with one's diurnal preference. CONCLUSION: Based on these findings, diurnal preference is valuable, above and beyond other psychological constructs, in predicting exercise frequency and represents an important variable to incorporate into interventions seeking to increase exercise.

Investigative fatigue: how sleep-circadian factors shape criminal investigations.

Investigating criminal complaints and identifying culprits to be prosecuted in the court of law is an essential process for law-enforcement and public safety. However, law-enforcement investigators operate under very challenging conditions due to stressful environments, understaffing, and public scrutiny, which factors into investigative errors (e.g. uncleared cases). This paper argues that one contributing factor to investigative failures involves sleep and circadian disruption of investigators themselves, known to be prevalent among law-enforcement. By focusing on investigative interviewing, this analysis illustrates how sleep and circadian disruption could impact investigations by considering three broad phases of (1) preparation, (2) information elicitation, and (3) assessment and corroboration. These phases are organized in a framework that outlines theory-informed pathways in need of empirical attention, with special focus on effort and decision-making processes critical to investigations. While existing evidence is limited, preliminary findings support some elements of investigative fatigue. The paper concludes by placing investigative fatigue in a broader context of investigative work while providing recommendations for future research throughout. This paper is part of the Sleep and Circadian Health in the Justice System Collection.

How emotions impact sleep: A quantitative review of experiments.

Although sleep and emotional processes are recognized as mutually dependent, the causal impact of emotions on sleep has been comparatively neglected. To appraise evidence for the causal influence of emotions on sleep, a meta-analysis of the existing experimental literature evaluated the strength, form, and context of experimental effects of emotion inductions on sleep parameters (k = 31). Quality of experiments was evaluated, and theoretically-relevant features were extracted and examined as moderating factors of observed effects (i.e., sleep parameter, design, sleep context, types of emotion inductions and emotions). Random-effect models were used to aggregate effects for each sleep parameter, while-mixed effect models examined moderators. There was a significant impact of emotion inductions on delayed sleep onset latency (D = 3.36 min, 95%CI [1.78, 4.94], g = 0.53), but not other parameters. There was little evidence of publication bias regarding sleep-onset latency effect, the studies overall were heterogeneous, sometimes of limited methodological quality, and could only detect moderate-to-large impacts. The findings supported the hypothesis that negative emotions delayed sleep onset, but evidence regarding other sleep parameters was inconclusive. The results call for more targeted investigation to disambiguate distinct features of emotions and their import for sleep.

A novel approach to model cumulative stress: Area under the s-factor curve.

OBJECTIVE: Using a large longitudinal sample of adults from the Midlife in the United States (MIDUS) study, the present study extended a recently developed hierarchical model to determine how best to model the accumulation of stressors, and to determine whether the rate of change in stressors or traditional composite scores of stressors are stronger predictors of health outcomes. METHOD: We used factor analysis to estimate a stress-factor score and then, to operationalize the accumulation of stressors we examined five approaches to aggregating information about repeated exposures to multiple stressors. The predictive validity of these approaches was then assessed in relation to different health outcomes. RESULTS: The prediction of chronic conditions, body mass index, difficulty with activities of daily living, executive function, and episodic memory later in life was strongest when the accumulation of stressors was modeled using total area under the curve (AUC) of estimated factor scores, compared to composite scores that have traditionally been used in studies of cumulative stress, as well as linear rates of change. CONCLUSIONS: Like endogenous, biological markers of stress reactivity, AUC for individual trajectories of self-reported stressors shows promise as a data reduction technique to model the accumulation of stressors in longitudinal studies. Overall, our results indicate that considering different quantitative models is critical to understanding the sequelae and predictive power of psychosocial stressors from midlife to late adulthood.

Causes and consequences of expectation trajectories: "high" on optimism in a public ballot initiative.

Although expectations are key theoretical antecedents of emotion and behavior, expectations are typically examined as static properties without deep consideration of their temporal dynamics. We surveyed residents of California over five time points, during the month preceding a public ballot initiative on cannabis legalization (California Proposition 19) and after the election, to examine both the causes and the consequences of residents' expectation trajectories regarding the vote's outcome. Our results point to the importance of changes in individuals' expectations over time. Specifically, well-informed voters were likely to lower their expectations regarding the measure's passage as the vote neared, in line with polling results, but being informed about the initiative had less impact on expectation trajectories among voters who favored the measure than among those who opposed it. Furthermore, supporters who maintained their optimism about the initiative's outcome over time were more likely to vote and were more disappointed following the measure's failure, compared with supporters who became more pessimistic. The findings suggest that temporal changes in people's optimism and expectations play a unique role in social behavior.

The impact of alertness vs. fatigue on interrogators in an actigraphic study of field investigations.

Investigative interviews (e.g., interrogations) are a critical component of criminal, military, and civil investigations. However, how levels of alertness (vs. sleepiness) of the interviewer impact outcomes of actual interviews is unknown. To this end, the current study tracked daily fluctuations in alertness among professional criminal investigators to predict their daily experiences with actual field interviews. Fifty law-enforcement investigators wore a sleep-activity tracker for two weeks while keeping a daily-diary of investigative interviews conducted in the field. For each interview, the investigators indicated how well they established rapport with the subject, how much resistance they encountered, how well they maintained their own focus and composure, and the overall utility of intelligence obtained. Daily alertness was biomathematically modeled from actigraphic sleep duration and continuity estimates and used to predict interview characteristics. Investigators consistently reported more difficulties maintaining their focus and composure as well as encountering more subject resistance during interviews on days with lower alertness. Better interview outcomes were also reported on days with subjectively better sleep, while findings were generally robust to inclusion of covariates. The findings implicate adequate sleep as a modifiable fitness factor for collectors of human intelligence.

Envy divides the two faces of narcissism.

In this article, we test psychodynamic assumptions about envy and narcissism by examining malicious envy in the context of narcissistic grandiosity and vulnerability. In Study 1, students (N = 192) and community adults (N = 161) completed trait measures of narcissism, envy, and schadenfreude. In Study 2 (N = 121), participants relived an episode of envy, and cognitive-affective components of envy were examined in the context of both self- and informant reports of their envy and narcissism. In Study 3 (N = 69), narcissism was linked to reports of envy covertly induced in the laboratory. Vulnerable narcissism was strongly and consistently related to dispositional envy and schadenfreude (Studies 1-2), as well as to all cognitive-affective components of envy (Study 2). Furthermore, it facilitated envy and schadenfreude toward a high-status peer (Study 3). Grandiose narcissism was slightly negatively related to dispositional envy (Studies 1-2), and it did not predict informant reports of envy or cognitive-affective components of the emotion (Study 2). Finally, it did not exacerbate envy, hostility, or resentment toward a high-status peer (Study 3). The results suggest envy is a central emotion in the lives of those with narcissistic vulnerability and imply that envy should be reconsidered as a symptom accompanying grandiose features in the diagnosis of narcissistic personality disorder.

The Iowa Resistance to Sleeplessness Test (iREST).

INTRODUCTION: Despite considerable individual differences in the vulnerability vs resistance to effects of sleep loss, there is no practical self-report tool to predict these differences across domains and only limited evidence whether they are general or domain-specific. To address this need, we developed the Iowa Resistance to Sleeplessness Test (iREST). METHODS: A construct-validation approach was employed. During the substantive phase, self-report items were generated to capture vulnerability vs resistance to sleep loss across various psycho-behavioral domains. During the structural phase, analyses identified the underlying factor structure and examined reliability of individual scale scores. Finally, the external phase used convergent and discriminant analyses to evaluate the factors in light of related sleep and personality measures, and tested criterion validity of the scale scores in predicting neurocognitive and affective responses to experimental sleep restriction (Total N = 1018). RESULTS: Analyses yielded discriminant and reliable scale scores that reflected resistance across cognitive, affective, and somatic responses, while also marking a general resistance factor. Convergent and discriminant probes revealed moderate associations of scale scores with daytime sleepiness and sleep-related distress, but small to negligible associations with other measures of sleep behavior, perceptions, and personality. Critically, criterion analyses yielded validity evidence for predicting cognitive and affective impairments in response to experimental sleep loss. CONCLUSION: Scores on the iREST show validity in capturing cognitive and affective resistance to moderate sleep loss among young adults, supporting its further exploration as a practical tool for predicting behavior due to lost sleep.

Sleep, emotional supportiveness, and socially straining behavior: A multidimensional approach.

OBJECTIVE: To determine the associations of emotional supportiveness toward others and engagement in socially straining (negative) behavior toward others across close relationships with multiple dimensions of sleep health. DESIGN: Cross-sectional. SETTING: Community sample from the Midlife in the United States study (MIDUS). PARTICIPANTS: Four-hundred and thirty-five participants from the MIDUS II Biomarker Project aged 35-85. MEASUREMENTS: Self-report assessments of being emotionally supportive and engaging in socially straining behavior toward friends, family, and romantic partners; self-report assessments of demographic and other psychological and health variables; 7 nights of wrist actigraphy and sleep diary. RESULTS: Being emotionally supportive and engagement in socially straining behavior were associated with multiple dimensions of sleep health. The inclusion of demographic, health, and psychological covariates reduced but did not eliminate these associations. Based on analyses adjusting for these covariates, being more emotionally supportive toward close others was most robustly related to higher daytime alertness, and engaging in more socially straining behavior was most robustly related to less sleep regularity, quality, and efficiency. CONCLUSIONS: These findings implicate sleep health as a substantive correlate of being emotionally supportive toward and imposing social strain on others. They show that both daytime and nighttime dimensions of sleep health are important for social functioning across close relationships and highlight the need to examine both positive and negative aspects of relationships in relation to sleep.

Sleep and interrogation: does losing sleep impact criminal history disclosure?

STUDY OBJECTIVES: Despite centuries of using sleep deprivation to interrogate, there is virtually no scientific evidence on how sleep shapes behavior within interrogation settings. To evaluate the impact of sleeplessness on participants' behavior during investigative interviews, an experimental study examined the impact of sleep restriction on disclosure of past illegal behavior. METHODS: Healthy participants from a university community (N = 143) either maintained or curbed their sleep (up to 4 h a night) across 2 days with sleep monitored via actigraphy. They were then asked to disclose past illegal acts and interviewed about them. Next, they were reinterviewed following an example of a detailed memory account (model statement). Disclosures were blindly coded for quantity and quality by two independent raters. RESULTS: Sleep-restricted individuals reported similar offenses, but less information during their disclosure with slightly less precision. Model statement increased disclosure but did not reduce the inhibiting impact of sleep loss. Mediation analysis confirmed the causal role of sleep as responsible for experimental differences in amount of information, and participants' reports suggested impaired motivation to recall information played a role. CONCLUSIONS: The findings suggest that even moderate sleep loss can inhibit criminal disclosure during interviews, point to motivational factors as responsible, and suggest investigators should be cautious when interrogating sleepy participants.

Wishful thinking in the 2008 U.S. presidential election.

In elections, political preferences are strongly linked to the expectations of the electoral winner-people usually expect their favorite candidate to win. This link could be driven by wishful thinking (a biasing influence of preferences), driven by a biasing influence of expectations on one's wishes, or produced spuriously. To examine these competing possibilities in the 2008 U.S. presidential election, a longitudinal study assessed uncommitted young voters' electoral expectations and preferences over four time points during the month before the election. The findings indicated clear support for wishful thinking: Over time, people's preferences shaped their expectations, but the reverse was not the case. Moreover, these relations were larger among those more strongly identified with their political party and held even when perceptions of general candidate popularity were taken into account. Finally, changes in electoral expectations were consequential, as they shaped disappointment in the electoral results even after taking candidate preferences into account.

Synthesizer 1.0: a varying-coefficient meta-analytic tool.

Meta-analysis has become an indispensable tool for reaching accurate and representative conclusions about phenomena of interest within a research literature. However, in order for meta-analytic computations to provide accurate estimates of population parameters (e.g., a population correlation), underlying statistical models need to be both efficient and unbiased. Current fixed-effect (i.e., constant-coefficient) models that assume a common effect for all research results perform poorly under conditions of effect size heterogeneity, whereas current random-effects (i.e., random-coefficient) models require unrealistic assumptions about random sampling of observed effect sizes from a normally distributed superpopulation. This article describes a free statistical software tool that employs a varying-coefficient model recently proposed by Bonett (2008, 2009). The software (Synthesizer 1.0) employs procedures that do not require effect homogeneity or random sampling of effect sizes from a normal distribution. It may be used to meta-analyze correlations, alpha reliabilities, and standardized mean differences. The Synthesizer tool for Microsoft Excel 2007 may be downloaded from the author at www.psychology.iastate.edu/~zkrizan/Synthesizer.htm or as a supplement to the article at http://brm.psychonomic-journals.org/content/supplemental.

Associations between screen time and short sleep duration among adolescents varies by media type: evidence from a cohort study.

STUDY OBJECTIVES: Different types of electronic screen media have repeatedly been linked to impaired sleep; yet, how different uses of electronic media are linked to sleep has received much less attention. Currently, the role of chronotype in these associations is understudied. To address these gaps, this study examined how different uses of screen media are linked to sleep, and whether these associations were accounted for or differed across chronotype. METHODS: Data were from 11,361 children aged 13 to 15 from the United Kingdom who participated in the 2015 wave of the Millennium Cohort Study. RESULTS: Heavy use of screen media was associated with shorter sleep duration, longer sleep latency, and more mid-sleep awakenings. The strongest associations emerged for using screen media to engage in social media or to use the internet. Overall, these associations were weakened, but remained after controlling for chronotype and tended to be the strongest amongst robins (children with an intermediate chronotype). CONCLUSIONS: Spending too much time on electronic devices is associated with multiple dimensions of impaired sleep, especially if this time on devices is used for social media or surfing the internet. Chronotype does not account for the associations between screen media and sleep and can be used to identify children who may be particularly susceptible to the effects of screen media on sleep.

Sleepy anger: Restricted sleep amplifies angry feelings.

Despite extensive ties between sleep disruption, anger, and aggression, it is unclear whether sleep loss plays a causal role in shaping anger. On one hand, negative affect and distress frequently follow curtailed sleep, suggesting increased anger responses. On the other hand, fatigue and withdrawal also follow, potentially muting anger. To examine these competing possibilities, 142 community residents were randomly assigned to either maintain or restrict their sleep over 2 days. Before and after, these participants rated their anger and affect throughout a product-rating task alongside aversive noise. Sleep restriction universally intensified anger, reversing adaptation trends in which anger diminished with repeated exposure to noise. Negative affect followed similar patterns, and subjective sleepiness mediated most of the experimental effects on anger. These findings highlight important consequences of everyday sleep loss on anger and implicate sleepiness in dysregulation of anger and hedonic adaptation. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Changes in sleep difficulties among the U.S. population from 2013 to 2017: results from the National Health Interview Survey.

OBJECTIVES: This study sought to evaluate how sleep difficulties have changed over time and to evaluate if these changes relate to changes in sleep duration. DESIGN: National Health Interview Survey administered annually from 2013 to 2017 by the National Center for Health Statistics. SETTING: U.S. national adult population. PARTICIPANTS: 164,696 U.S. adults sampled across the nation using multistage area probability design. MEASUREMENTS: Self-reports of difficulties falling asleep, trouble staying asleep, use of sleep medication, feelings of restorative sleep, and sleep duration collected each year. RESULTS: From 2013 to 2017, the prevalence of reporting any days with difficulty falling asleep (B = .01, p <.01), trouble staying asleep (B = .02, p < .001), increased, yet waking feeling rested also increased (B = .01, p = .004), while average sleep duration decreased (B = -.02, p < .001). Moreover, changes in these sleep difficulties were independent of sleep duration and primarily occurred in healthy sleepers. CONCLUSIONS: Multiple aspects of sleep difficulties show an undesirable trajectory in the U.S. adult population. Moreover, these trends appear to be independent of sleep duration and are primarily occurring in healthy sleepers. Future research should simultaneously consider how multiple aspects of sleep are changing and further examine the sources of these changes.

Does Stress Explain the Effect of Sleep on Self-Control Difficulties? A Month-Long Daily Diary Study.

Insufficient sleep is linked to increased stress and suboptimal self-control; however, no studies have examined stress as a reason for why sleep affects self-control. Moreover, it is unknown if there are individual differences that make people vulnerable to this dynamic. Daily diary entries from 212 university students across 30 days were used in a multilevel path model examining if stress explained how prior night sleep affected next-day self-control difficulties and exploring if individual differences in sleep duration, stress, or self-control qualified this effect. Increased stress partially mediated of the effect of reduced sleep duration on increased next-day self-control difficulty. Moreover, short sleep increased next-day stress more for individuals with higher typical stress. Daytime stress especially amplified self-control difficulty for individuals with shorter typical sleep duration. Findings implicate stress as a substantial factor in how sleep loss undermines self-control and identify individuals particularly susceptible to this effect.

Associations between screen time and sleep duration are primarily driven by portable electronic devices: evidence from a population-based study of U.S. children ages 0-17.

STUDY OBJECTIVES: Excessive screen time in child and adolescent populations is associated with short sleep duration, but the unique effects of portable vs. non-portable electronic devices has received little attention. Moreover, it is unknown whether the effects of these devices change across childhood. To address these gaps, the current study compared the association of portable vs. non-portable electronic devices with sleep duration throughout childhood. METHODS: Data were from a 2016 national survey of the caregivers of 43,755 children and adolescents ages 0-17 administered by the U.S. Census Bureau. RESULTS: Children and adolescents who spent more time on screens slept fewer hours and were more likely to get insufficient sleep. In multivariate regressions including time spent on TV and video game consoles and portable electronic devices, associations with sleep duration were primarily due to portable electronic devices. These results remained when demographic variables, diagnoses of anxiety or depression, physical activity, and BMI were included in the model. Moreover, time spent using both portable and non-portable devices was important for sleep duration in children under age 10, but the importance of non-portable devices diminished in children over 10. CONCLUSIONS: Spending multiple hours a day on electronic devices is associated with shorter sleep duration across all ages. However, portable electronic devices have a stronger association with sleep duration than non-portable electronic screens, with non-portable devices less relevant for sleep duration in children over age 10. The findings suggest that future interventions should uniquely target portable electronic devices while also accounting for the age group of children targeted.