This longitudinal study examined the predictive role of emotion reactivity and regulation on sleep quality across early to middle childhood. Participants were typically developing Swedish children (N = 116, 49% girls), with reactivity and regulation assessed at ages 3, 6 and 9 years, and sleep quality measured at the age of 9 years. Results provided partial support for preregistered hypotheses. Regulation was consistently associated with sleep quality, with concurrent regulation at the age of 9 years showing the strongest association. Reactivity only correlated with sleep quality at the age of 9 years. Exploratory path analysis showed more complex patterns. Regulation emerged as the most consistent predictor of better sleep quality. Early reactivity (ages 3 and 6 years) showed small positive links to later sleep, whereas higher concurrent reactivity at the age of 9 years predicted poorer sleep quality. Mediation analyses suggested that regulation may serve as a mechanism linking reactivity to later sleep quality. Together, these findings underscore both the developmental value and the complexity of emotion–sleep relations, highlighting the need for nuanced, context-sensitive approaches to understanding how emotional functioning supports children's sleep health.

Pursuing replicability — independent evidence for previous claims — is important for creating generalizable knowledge. Here we attempted replications of 274 claims of positive results from 164 quantitative papers published from 2009 to 2018 in 54 journals in the social and behavioural sciences. Replications were high powered on average to detect the original effect size (median of 99.6%), used original materials when relevant and available, and were peer reviewed in advance through a standardized internal protocol. Replications showed statistically significant results in the original pattern for 151 of 274 claims (55.1% (95% confidence interval (CI) 49.2–60.9%)) and for 80.8 of 164 papers (49.3% (95% CI 43.8–54.7%)), weighed for replicating multiple claims per paper. We observed modest variation in replication rates across disciplines (42.5–63.1%), although some estimates had high uncertainty. The median Pearson’s r effect size was 0.25 (95% CI 0.21–0.27) for original studies and 0.10 (95% CI 0.09–0.13) for replication studies, an 82.4% (95% CI 67.8–88.2%) reduction in shared variance. Thirteen methods for evaluating replication success provided estimates ranging from 28.6% to 74.8% (median of 49.3%). Some decline in effect size and significance is expected based on power to detect original effects and regression to the mean because we replicated only positive results. We observe that challenges for replicability extend across social–behavioural sciences, illustrating the importance of identifying conditions that promote or inhibit replicability.

Meta-metacognition is the awareness of our own metacognition. In this paper, following the work of Recht et al. (2022), meta-metacognitive judgments will be referred to as third-order judgments in which the judgement is about evaluating the accuracy of a metacognitive judgment (second order), which in turn is a prediction about the success or failure of the outcome of a cognitive process (first order). Although meta-metacognition is a scarcely studied topic, there are a sufficient number of papers now to conclude that people make accurate third-order judgments across both prospective and retrospective metacognition. We review the literature here with a particular focus on the methods employed to study meta-metacognition. We then make some suggestions for how to advance the study of meta-metacognition. In particular, we think applying the view that third-order judgments arise from inferential/heuristic processes would be a fruitful area of study.

This study examined the predictive effect of day-to-day variations in sleep on self-reported social motivation and social activity in 126 parents of young children with sleep problems. Controlling for other sleep factors, worse subjective sleep quality predicted less morning sociability and social motivation throughout the day. Unexpectedly, longer sleep duration predicted less social activity the following day. Sleepiness at wakeup predicted morning sociability, but not social motivation or activity throughout the day. This highlights the importance of good sleep quality for motivation to socialize, but also the complexity of investigating the relationship between sleep and social measures in daily life.

Sleep loss impairs many cognitive functions, ranging from simple attention to working memory. This study explores the extent to which people are aware of such impairments, their metacognitive accuracy, across different cognitive tests. Healthy participants (N = 182) were randomised to one night of total sleep deprivation or three nights of sufficient sleep. The next day they performed several cognitive tests, measuring simple attention, cognitive throughput, working memory, episodic memory and executive processing (using a Stroop task). After each test, participants rated how well they thought they performed. We operationalised metacognitive accuracy as the ability to correctly identify whether one performed above or below the median. We then used Bayesian methods to estimate the difference in this ability between the well-rested and sleep-deprived groups. The probability was 55% in the sleep-deprived group, and 59% in the rested group, suggesting some decrease in performance awareness during sleep loss. However, the probability that this difference in judgements is practically significant (i.e., exceeding 10 percentage points) is below 1%. Cognitive ability generally declines during sleep deprivation, and this was at least somewhat reflected in a decrease in how people rated their performance. The question remains whether and how people compensate for any sleep-loss induced cognitive impairments.

An international expert group (European Sleep Foundation Think Tank) convened in 2022 to discuss the state of the evidence in the domain of hypersomnolence. The expert group considered the current state of knowledge based on the most relevant recent publications, discussed the current challenges in the field and identified future priorities. The purpose of this white paper is to summarize the definition, diagnosis, and pathophysiology of hypersomnolence, the epidemiology, phenotype, and management of hypersomnolence in obstructive sleep apnea and in neurological and psychiatric disorders, and the impact of hypersomnolence on daily activities, workability and health-related quality of life. The key results of the discussion were that: a) hypersomnolence is both prevalent and heterogeneous in its manifestations in a wide variety of pathological conditions encompassing obstructive sleep apnea and neurological and psychiatric disorders; and b) while multiple pathophysiological pathways are potentially involved in hypersomnolence, knowledge of the specific causal factors in individual patients remains undefined, and the specific factors responsible for excessive daytime sleepiness vs. excessive need for sleep remain largely unclear. The clinical implications of these results are the occurrence of important limitations to the development of personalized approaches to diagnosis, prognosis, and management of hypersomnolence, which is essential considering the high societal and personal costs of hypersomnolence, and its substantial adverse impact on quality of life. Research priorities should address these limitations with improved quantification of hypersomnolence and with an evidence base on the costs and benefit of hypersomnolence management in patients with respiratory, neurologic, and psychiatric disorders.

While altered motivation is central in sickness behavior, previous research has mainly focused on motivation for rewards, rather than motivational changes in a broader perspective. In a larger study following a randomized within-subject placebo-controlled crossover design, we investigated the effects of systemic inflammatory activation on self-rated motivation in 21 healthy participants, using an intravenous injection of 2.0 ng/kg body weight lipopolysaccharide (LPS) compared to an intravenous injection of saline (placebo). Self-rated motivation was measured before, 3 h, and 7.5 h post-injection using the Motivation Scale of Sickness (MOSSick), a newly developed tool designed to assess motivational changes during sickness. It contains 26 items covering motivational drives related to hunger, thirst, and food preferences; resting, physical, and social activities; care seeking; and utilization of resources (i.e., willingness to ‘pay’ and ‘walk’) to be able to rest or to be healthy at once. At the peak of the sickness response (3 h post-LPS injection), there was an increased motivation to seek care, rest, and sleep, as compared to placebo, while motivation to partake in physical and social activities decreased. Several of these effects remained at 7.5 h post-injection. When in the LPS condition, participants were also willing to pay more money to rest and to be healthy compared to when in the placebo condition. Hunger increased over time in both conditions, but less after LPS administration. During the peak of the sickness response, higher sickness ratings were weakly associated with lower motivation for social activities and higher motivation for resting and sleeping. No further association was found between motivational drives and sickness ratings or other sickness measures, i.e. concentrations of cytokines and tympanic temperature, although sample size was limited for these analyses. These findings illustrate that motivational changes during acute sickness are not restricted to a general decrease in motivation. Instead, sick individuals are more motivated to take part in behaviors that enable energy preservation, care, and recovery, compared to when healthy.

Pressing the snooze button is a common way to start the day, but little is known about this behaviour. Through two studies we determined predictors and effects of snoozing. In Study 1 (n = 1732) respondents described their waking habits, confirming that snoozing is widespread, especially in younger individuals and later chronotypes. Morning drowsiness and shorter sleep were also more common for those who snooze. Study 2 was a within-subjects laboratory study (with polysomnography) on habitual snoozers (n = 31), showing that 30 min of snoozing improved or did not affect performance on cognitive tests directly upon rising compared to an abrupt awakening. Bayes factors indicate varying strengths of this evidence. Snoozing resulted in about 6 min of lost sleep, while preventing awakenings from slow-wave sleep (N3). There were no clear effects of snoozing on the cortisol awakening response, morning sleepiness, mood, or overnight sleep architecture. A brief snooze period may thus help alleviate sleep inertia, without substantially disturbing sleep, for late chronotypes and those with morning drowsiness.

Introduction: The social effects of insufficient sleep represent a relatively new area of study in sleep research. For instance, the influence of sleep on verbal communication, particularly communicative perspective-taking and adaptation based on audience, is underexplored. Furthermore, studies on how sleep affects speaking patterns are limited, although slowed speech has been indicated as an effect of sleep loss. Given the importance of effective communication in all areas of life, understanding the harmful effects of insufficient sleep on communication is vital. The present study investigated whether sleep restriction affects speech speed and the ability to adjust one's speech depending on the listener.

Method: In an experimental cross-over study, 273 participants described nine abstract figures separately to a child and an adult, both of whom were depicted as photos on a computer screen. This task was completed under two conditions: sleep-saturated (nine in bed hours/night for two nights) and sleep-restricted (four hours in bed/night for two nights). The descriptions were analysed for number of words spoken per minute, average number of words spoken per figure described, and average word length.

Results: Using mixed linear models, we found that sleep restriction significantly reduced speech speed by about 3.52 words per minute (p = 0.003) and decreased the number of words used per figure by 2.20 (p < 0.001), with no difference in word length (p = 0.261). Participants adapted their speech depending on whether the listener was a child or an adult by using fewer words per figure (1.71 fewer words, p < 0.001) and shorter words (0.02 fewer letters, p = 0.011) when speaking to a child. There was no difference in how quickly they spoke to a child compared to an adult (p = 0.136). Additionally, no interaction effects were observed between sleep condition and whether the listener was an adult or a child (all p > 0.570).

Conclusion: Although sleep restriction led to slowed speech, it did not significantly impair the tendency to tailor one's speech to different listeners. These findings suggest a resilience in the social cognitive processes involved in tailoring speech to different audiences following insufficient sleep.

Fluid intelligence is seen as a beneficial attribute, protecting against stress and ill-health. Whether intelligence provides resilience to the cognitive effects of insufficient sleep was tested in the current pre-registered experimental study. Participants (N = 182) completed the Raven's test (measuring fluid intelligence) and a normal night of sleep or a night of total sleep deprivation. Sleepiness and four cognitive tests were completed at 22:30 hours (baseline), and the following day after sleep manipulation. At baseline, higher fluid intelligence was associated with faster and more accurate arithmetic calculations, and better episodic memory, but not with spatial working memory, simple attention or sleepiness. Those with higher fluid intelligence were more, not less, impacted by sleep deprivation, evident for arithmetic ability, episodic memory and spatial working memory. We need to establish a more nuanced picture of the benefits of intelligence, where intelligence is not related to cognitive advantages in all situations.