Traders in global markets operate at different local times-of-day. This implies heterogeneity in circadian timing and likely sleepiness or alertness of those traders operating at less or more optimal times of the day, respectively. This, in turn, may lead to differences in both individual-level trader behavior as well as market level outcomes. We examined these factors by administering single-location and global sessions of an online asset market experiment that regularly produces mispricing and valuation bubbles. Global sessions involved real time trades between subjects in New Zealand and the U.S (i.e., “global” markets) with varied local times of day for each location. Individual traders at suboptimal times of day (or, “circadian mismatched” traders) engaged in riskier trading strategies, such as holding shares (the riskier asset) in later trading rounds and mispricing shares to a greater degree. These strategies resulted in lower earnings for circadian mismatched traders, especially in heterogeneous markets that also included traders at more optimal times-of-day. These differences were also reflected in market level outcomes. Markets with higher circadian mismatch heterogeneity across traders were more likely to exhibit longer lasting asset bubbles and greater share turnover volume. Overall, our results draw attention to a unique, but underappreciated, factor present across traders in global market environments, namely, differences in sleepiness across traders. Thus, this study hopes to highlight the role of circadian mismatch in attempting to understand trader behavior and, ultimately, market volatility.

The ability to strategically reason is important in many competitive environments. In this paper, we examine how relatively mild temporal variations in cognition affect reasoning in the Beauty Contest. The source of temporal cognition variation that we explore is the time-of-day that decisions are made. Our first result is that circadian mismatched subjects (i.e., those making decisions at off-peak time of day) display lower levels of strategic reasoning in the p < 1 Beauty Contest but not in the p > 1 game. This suggests that a cognitively more challenging environment is required for circadian mismatch to harm strategic reasoning. A second result is that choice adaptation or mimicry (i.e., a more automatic type of responding than what is typically considered to be “learning”) during repeated play is not significantly affected by circadian mismatch. This is consistent with the hypothesis that automatic thought is more resilient to cognitive resource depletion than controlled-thought decision making.

It is common in mental health care to ask about people’s days but comparatively rare to ask about their nights. Most patients diagnosed with schizophrenia struggle at nighttime. The next-day effects can include a worsening of psychotic experiences, affective disturbances, and inactivity, which in turn affect the next night’s sleep. Objective and subjective cognitive abilities may be affected too. Patients commonly experience a mix of sleep difficulties in a night and across a week. These difficulties include trouble falling asleep, staying asleep, or sleeping at all; nightmares and other awakenings; poor-quality sleep; oversleeping; tiredness; sleeping at the wrong times; and problems establishing a regular sleep pattern. The patient group is also more vulnerable to obstructive sleep apnea and restless legs syndrome. We describe in this article how the complex presentation of non-respiratory sleep difficulties arises from variation across five factors: timing, mental state, need for sleep, self-care, and environment. We set out 10 illustrative patterns of such difficulties experienced by patients with non-affective psychosis. These sleep problems are eminently treatable with intensive psychological therapy delivered over approximately eight sessions. We describe key techniques and their typical order of implementation by presentation. Sleep problems are an important issue for patients. Giving them the therapeutic attention patients often desire brings both real clinical benefits and improves views of services. Treatment is also very likely to lessen psychotic experiences and mood disturbances while improving daytime functioning and quality of life. Tackling sleep difficulties can be a route toward the successful treatment of psychosis.

As obesity rates rise globally, addressing modifiable lifestyle factors, such as sleep, presents an opportunity for public health interventions. This review explores the growing evidence linking sleep duration, quality and timing with weight management and dietary behaviours throughout the life course. Observational studies associate short or irregular sleep with increased obesity risk, poor diet quality and metabolic disturbances. Plausible mechanisms include decreased physical activity, heightened hedonic and/or emotional eating, dysregulated appetite signals and circadian misalignment of metabolism, which contribute to a positive energy balance. Unravelling the bidirectional relationship between sleep and weight is challenging; poor sleep exacerbates weight gain, while obesity-related comorbidities such as obstructive sleep apnoea further impair sleep. Despite promising evidence from sleep-restriction studies showing increased energy intake, long-term randomised controlled trials (RCTs) examining interventions designed to improve sleep with weight management as an outcome are lacking. A handful of short-term interventions suggest benefits in reducing energy intake or improving dietary quality, but their effects on weight loss remain inconclusive. This review calls for robust, well-powered RCTs that integrate sleep, diet and physical activity interventions to evaluate the potential of sleep as a core component of obesity prevention and treatment strategies. Currently, there is insufficient evidence to support sleep-focused interventions as a mandatory element in clinical weight-management programmes.

Should you take a pill that gives you all the health benefits of sleep and allows you to stay awake? I argue that you shouldn’t. I propose three reasons why sleeping, conceived of as a socially and culturally embedded human activity, is valuable. First, there is aesthetic value in the rituals that typically precede sleeping; second, there is interpersonal value in the intimacy that stems from sleeping with other people; third, there is ethical value in mere presence and in retreating from consciousness. In order to fully support my argument, I situate it within a conception of goodness that embraces the fragility of the human condition and the limitations stemming from our corporeal nature. I conclude with some practical implications of my view.

There is growing interest in lifestyle interventions as stand-alone and add-on therapies in mental health care due to their potential benefits for both physical and mental health outcomes. We evaluated lifestyle interventions focusing on physical activity, diet, and sleep in adults with severe mental illness (SMI) and the evidence for their effectiveness. To this end, we conducted a meta-review and searched major electronic databases for articles published prior to 09/2022 and updated our search in 03/2024. We identified 89 relevant systematic reviews and assessed their quality using the SIGN checklist. Based on the findings of our meta-review and on clinical expertise of the authors, we formulated seven recommendations. In brief, evidence supports the application of lifestyle interventions that combine behavioural change techniques, dietary modification, and physical activity to reduce weight and improve cardiovascular health parameters in adults with SMI. Furthermore, physical activity should be used as an adjunct treatment to improve mental health in adults with SMI, including psychotic symptoms and cognition in adults with schizophrenia or depressive symptoms in adults with major depression. To ameliorate sleep quality, cognitive behavioural informed interventions can be considered. Additionally, we provide an overview of key gaps in the current literature. Future studies should integrate both mental and physical health outcomes to reflect the multi-faceted benefits of lifestyle interventions. Moreover, our meta-review highlighted a relative dearth of evidence relating to interventions in adults with bipolar disorder and to nutritional and sleep interventions. Future research could help establish lifestyle interventions as a core component of mental health care.

Sleep is vital for the maintenance of physical and mental health, recovery and performance in athletes. Sleep also has a restorative effect on the immune system and the endocrine system. Sleep must be of adequate duration, timing and quality to promote recovery following training and competition. Inadequate sleep adversely impacts carbohydrate metabolism, appetite, energy intake and protein synthesis affecting recovery from the energy demands of daily living and training/competition related fatigue. Sleep’s role in overall health and well-being has been established. Athletes have high sleep needs and are particularly vulnerable to sleep difficulties due to high training and competition demands, as such the implementation of the potential nutritional interventions to improve sleep duration and quality is commonplace. The use of certain nutrition strategies and supplements has an evidence base i.e. carbohydrate, caffeine, creatine, kiwifruit, magnesium, meal make-up and timing, protein and tart cherry. However, further research involving both foods and supplements is necessary to clarify the interactions between nutrition and the circadian system as there is potential to improve sleep and recovery. Additional research is necessary to clarify guidelines and develop products and protocols for foods and supplements to benefit athlete health, performance and/or recovery. The purpose of this review is to highlight the potential interaction between sleep and nutrition for athletes and how these interactions might benefit sleep and/or recovery.

Infant sleep quality is increasingly regarded as an important factor for children long-term functioning and adaptation. The early roots of sleep disturbances are still poorly understood and likely involve a complex interplay between prenatal and postnatal factors. This study investigated whether exclusive breastfeeding during the first 6 months moderated the association between maternal prenatal pandemic-related stress (PRS) and sleep problems in 24-months children born during the COVID-19 pandemic. We also explored the potential contribution of maternal postnatal anxiety in these relations. Seventy-eight infants (50% males) and their mothers provided complete data from birth to 24 months. Between 12 and 48 h from birth, maternal PRS during pregnancy was retrospectively reported as well as maternal anxiety and exclusive breastfeeding. Maternal anxiety and exclusive breastfeeding were also reported at 3 and 6 months after childbirth. Children sleep disturbances were reported at 24 months. Bayesian analyses revealed that maternal PRS was positively associated with sleep problems in children who were not exclusively breastfed from birth to 6 months. Findings add to the growing literature on the lasting impact of early pre- and postnatal experiences on child well-being and development.

This editorial summarises the clinical relevance of ‘chronopsychiatry’, defined as the interface between circadian science and mental health science. Chronopsychiatry represents a move towards time-variable perspectives on neurobiology and symptoms, with a greater emphasis on chronotherapeutic interventions.

I would like to thank Professor Ekirch for his reflections on ‘Have we lost sleep?’, which contain several points that I have already responded to within the paper following his peer review of my original submission to Medical History in 2023 (Professor Ekirch having voluntarily identified himself as a reviewer in a normally double-blind process). I acknowledge that the focus of my paper was on Ekirch’s original work from 2001; if I did not engage as he would have wished with his subsequent publications, this was simply because I do not perceive the same substantial developments in his thinking and research on the subject that he does. Indeed, the present critique by Ekirch amounts essentially to more of the same: a long list of references and quotes but little detailed discussion of any individual source. As my paper demonstrates, seemingly unambiguous evidence from a brief quotation can become less clear-cut when placed in context. I am sorry if I deploy the word ‘might’ more than Ekirch would like. This reflects, I hope, a healthy degree of uncertainty and intellectual humility in my approach to the complex issue of pre-industrial sleep. To extend Ekirch’s metaphor, if the jigsaw puzzle that both he and I are trying to assemble can take the form of a cat or a dog, it is possible that its true form is neither animal. The extent to which people woke in the night in pre-industrial Europe, the duration of such awakening, and the predominant cultural attitude towards this—concern, acceptance, or indifference—are topics about which it would seem wise to avoid sweeping statements and generalisations, given the relatively long period covered and the social, cultural, and individual diversity that must be taken into consideration. I can only repeat that I think amassing more brief references, and selectively citing relatively small physiological studies and anthropological evidence from global settings, is unlikely to provide much clarity, let alone definitive answers. I welcome Professor Ekirch’s contribution to this discussion as an indication that the question of segmented sleep in early modern Europe is by no means settled but is a matter of ongoing debate.

The objective was to examine associations between social jetlag and diet quality among young adults in the US using nationally representative data from the 2017–2018 NHANES survey, and evaluate effect modification by gender and race/ethnicity. Social jetlag was considered ≥2-hour difference in sleep midpoint (median of bedtime and wake time) between weekends and weekdays. Diet quality was assessed with the Healthy Eating Index (HEI)-2015 and its 13 dietary components. Ordinal logistic models were run with diet scores binned into tertiles as the outcome. Models accounted for potential confounders and survey weights. Effect modification by gender and race/ethnicity was examined. The study sample included 1,356 adults aged 20–39 years. 31% of young adults had social jetlag. Overall, there were no associations between social jetlag and diet quality. However, interaction analysis revealed several associations were race-specific (P, interaction<0.05). Among Black adults, social jetlag was associated with lower overall diet quality (OR = 0.4, 95% CI 0.2, 0.8; i.e. less likely to be in higher diet quality tertiles) and more unfavourable scores on Total Vegetables (OR = 0.6, 95% CI 0.3, 1.0) and Added Sugar (i.e. OR = 0.6, 95% CI 0.4, 0.9). For Hispanic adults, social jetlag was associated with worse scores for Sodium (OR = 0.6, 95% CI 0.4, 0.9) However, White adults with social jetlag had better scores of Greens and Beans (OR = 1.9, 95% CI 1.1, 3.2). Within a nationally representative sample of US young adults, social jetlag was related to certain indicators of lower diet quality among Black and Hispanic Americans.