Machine-learning-based sleep staging models have achieved expert-level performance on standard polysomnographic (PSG) data. However, their application to EEG recorded by wearable devices remains limited by non-conventional referencing montage and the lack of benchmarking against PSG. Here, we tested whether an ensemble of state-of-the-art staging algorithms can reliably classify sleep from a customised configuration of the ZMax headband, adapted to record a fronto-mastoid EEG channel. Thirty-five nights of simultaneous ZMax and PSG recordings were acquired in a home setting, yielding 250.02 h of data from 10 healthy participants. PSG data were scored according to AASM criteria by two independent experts, with discrepancies resolved to obtain a consensus hypnogram. ZMax signal was processed using four machine-learning algorithms (YASA, U-Sleep, SleepTransformer, DeepResNet), whose predictions were combined into a final ensemble scoring through soft voting. Quantitative/qualitative analyses of NREM slow waves and spindles evaluated the preservation of microstructural features across recording systems. The ensemble scoring achieved almost perfect agreement with human consensus staging (night-level mean ± SD; accuracy = 88.83% ± 2.84%, Cohen's κ = 84.10% ± 4.52%, and Matthews Correlation Coefficient = 84.54% ± 4.23%). It showed excellent classification efficiency for REM (F1-score = 93.99%), N3 (89.53%), N2 (87.93%), and wakefulness (86.37%), with lower performance for N1 (53.20%). Microstructural comparisons confirmed strong correspondence between ZMax and PSG signals. These findings support the deployment of an ensemble scoring approach based on state-of-the-art sleep staging algorithms on ultra-minimal EEG setups. This paradigm advances the integration of data from modern wearable technologies into traditional PSG-based sleep research, overcoming longstanding barriers to ecological, large-scale sleep monitoring.

Chronotype, the individual propensity towards morningness or eveningness, is a transdiagnostic factor implicated in mental health. How chronotype covaries with distinct psychiatric symptoms across the adult lifespan remains underinvestigated. In this cross-sectional study, 428 participants (18–70 years, evenly distributed across five age groups; 282 women, 143 men, other gender identity) completed the Reduced Morningness-Eveningness Questionnaire to approximate chronotype, and 11 validated scales assessing common psychiatric symptoms. Regression analyses and generalized additive models (GAMs) were used to examine linear and nonlinear relationships between chronotype, age, and psychiatric symptoms. Eveningness was associated with (in decreasing order of strength): emotion dysregulation, attention-deficit/hyperactivity disorder (ADHD), depression, autism, emotional instability, generalized anxiety, social anxiety, and impulsivity symptoms. Morningness was associated with mania symptoms. No significant associations were found between chronotype and delusional ideation or obsessive compulsive disorder (OCD) symptoms. Psychiatric symptom severity was generally lower with increasing age, particularly for emotional instability, emotion dysregulation, and ADHD. Nonetheless, certain symptoms persisted across age in eveningness (depression, generalized anxiety, OCD, ADHD), while other symptoms were lower (mania) or higher (social anxiety and delusional ideation) with eveningness at older ages. Except for mania symptoms, morningness in older age was not associated with higher symptom burden than eveningness for any other psychiatric domains. These results are consistent with the idea that morningness may be protective, being associated with lower psychiatric symptom levels in both younger and older age groups. In contrast, eveningness was associated with higher levels of autism, social anxiety and delusional ideation symptoms in older age.

Introduction: Quick return (<11h between shifts, QRs) have been common in Swedish Healthcare. Previous research has shown an association between QRs and increased risk for sick leave. The mechanisms driving this association could be related to short sleep as sleep length is reduced by ~1 hour in relation to quick returns. Short sleep could alter the activation of the hypothalamic-pituitary-adrenal (HPA)-axis, increase inflammation and increase risk for metabolic diseases. The aim of the study was to explore the acute effects of a quick return on blood markers for stress, inflammation and metabolism.

Methods: Newly graduated nurses were recruited via the introduction program for new nurses at one university hospital in Sweden. Of the 54 nurses recruited 24 participants completed participation. They were followed during two pre-scheduled work periods, with and without a quick return. The order of the two conditions was randomized across participants. The participants left blood samples in the morning (fasting) and afternoon of the second day in both conditions; “evening-day-day” versus “day-day-day.” Both conditions were preceded by a day off work. Food intake was standardized during sampling days. Blood samples were analyzed for creatinine, glucose, erythropoietin and cortisol using ELISA kits. Further analysis from U-PLEX Custom Metabolic Group 1 V-PLEX Custom Human Biomarkers 1 are ongoing and will be presented at the conference. The data were analyzed with an ANOVA examining the effects of the conditions, time of day, and interaction effects between conditions and time of day (18 participants had complete blood samples at both conditions).

Results: There was a significant effect of condition on creatinine (F=5.04; p < 0.05; df=1,17) and cortisol (F=9.58, p < 0.01; df=1,17) which were higher both in the morning and in the afternoon after a quick return. There were no significant effects of condition on CRP (F=0.32; p>0.05; df=1,17), erythropoietin (F=0.02; p>0.05; df=1,17) or glucose (F=1.26; p>0.05; df=1,17). None of the outcome measures showed a significant effect on condition and time of day.

Conclusion: The results indicate that an acute effect of a quick return is increased activation of the HPA-axis with higher levels of cortisol throughout the day. This increase was not mirrored by changes in glucose, erythropoietin or inflammatory levels. While this study indicates that quick returns leads to an acute (and probably functional) stress response, future studies should determine in what circumstances this stress may be harmful.

A behavioral defense against disease involves detecting sickness cues in others and responding adaptively, such as by avoiding social interactions. While studies have shown that humans can discriminate sickness cues above chance in faces after sickness induction, whether this discrimination affects approach-avoidance behaviors remains uncertain. Here, we investigated how facial sickness cues influence judgments of trustworthiness, serving as a proxy measure for social avoidance. In a prior study, facial photographs were taken of 21 individuals when sick (two hours after an endotoxin injection causing a transient systemic inflammation) and healthy (following placebo injection). In the current study, participants in two separate experiments viewed these paired facial photographs and were asked, in a two-alternative forced-choice paradigm, to identify which face appeared sick (n = 94) or more trustworthy (n = 82). Participants discriminated sick faces significantly above chance (73.1 %), with females (76.0 %) performing significantly better than males (69.3 %). Additionally, sick faces were perceived as significantly less trustworthy, being selected in only 34.9 % of trials. Notably, the higher the sickness discrimination accuracy for a particular face, the less likely that face was to be judged as trustworthy. Moreover, females (30.5 %) were significantly less likely than males (39.5 %) to judge sick faces as the more trustworthy looking. Individual differences in participants’ disease vulnerability, disgust sensitivity, and frequency of sickness, as well as facial stimulus participants’ inflammatory response intensity measured via interleukin-6 blood concentrations, body temperature, and sickness symptoms, did not predict sickness discrimination accuracy or trustworthiness judgments. Together, these findings suggest that visual sickness cues negatively affect trustworthiness judgments, potentially reflecting social avoidant behaviors towards individuals who appear sick. While judgments of facial trustworthiness may be considered a social inference about whether an individual is safe to approach, future research should also include manifest measures of approach-avoidance in response to sickness cues.

Arousal is a central component of many emotional symptoms and can contribute to insomnia. Here we assessed how the timing and fluctuating nature of arousal-related symptoms over the course of the day relate to insomnia symptom severity. In this study, 361 participants (M age = 31.9 years, 282 women, 77 men, 2 non-binary individuals) completed the Insomnia Severity Index to assess severity of insomnia symptoms, followed by repeated ratings of anxiety or nervousness, stress, sleepiness, and feeling down via their mobile phone between ~08:00 hours and 00:00 hours across 1 day. Measures of dynamics included: mean levels across the day; variation (standard deviation); instability (mean squared successive differences); and resistance to change/inertia (first-order autocorrelation). Time-of-day patterns were modelled using generalized additive mixed effects models. Insomnia symptom severity (mean Insomnia Severity Index = 9.1, SD = 5.2, range 0–25) was associated with higher mean levels of all arousal-related symptoms, and increased instability and variation throughout the day in anxiety or nervousness, stress, and feeling down. Resistance to change (inertia) was not associated with insomnia symptom severity. Generalized additive mixed effects analyses showed that while individuals with more severe insomnia symptoms had elevated symptoms across the entire day, they were especially more anxious or nervous and sleepy in the early morning (~08:00 hours), anxious or nervous, stressed and sleepy in the late afternoon/early evening (~16:00 hours–21:00 hours), and anxious or nervous and stressed in the late evening (~22:00 hours). Remarkably, higher arousal occurred in the presence of high subjective sleepiness. Together these results indicate that insomnia symptom severity is associated with problems with daytime and evening arousal regulation.

Introduction: Quick returns (<11h between shifts, QRs) result in shortened sleep length (~5–6h) and increased sleepiness and are thus likely to have a negative impact on work performance. Previous registry studies and field studies utilizing retrospective ratings have associated QRs with an increased risk of accidents and mistakes, but there is a shortage of studies that have adopted an experimental design to assess the acute effects of quick returns on work performance. The aim of the present experimental field study was to investigate differences in objective and subjective measures of sleep, sleepiness and cognitive performance between QRs and day-day transitions.

Methods: In the years 2018–2023, 67 newly graduated nurses were recruited from the introductory program at 3 Swedish university hospitals. In total, 35 completed participation and were followed during two pre-scheduled work periods, with and without a quick return (evening-day versus day-day). Both conditions were preceded by a day off work, and the order of the two conditions was randomized across participants. The participants wore an actigraphy watch during sleep and kept a sleep diary (Karolinska Sleep Diary) and a work diary throughout the day. In addition, the participants performed smartphone based cognitive tests three times a day on the KarolinskaWakeApp. The cognitive tests measured simple attention, episodic memory (memorizing a list of words) and cognitive conflict (Stroop). The data has been analyzed using Bayesian linear mixed models. Pre-registered analysis plan and priors can be found here: https://osf.io/kr4su.

Results: Nurses were estimated to sleep on average 6h 57min (95% Compatibility Interval [6h40m, 7h15m]) during day-day transitions and 49 minutes (95% CI [70,27]) shorter during quick returns. Sleep fragmentation did not differ between conditions, but the participants were more anxious at bedtime (-1.19, 95% CI [.89, 1.47]). Following a QR, participants felt less rested (0.64, 95% CI [0.32, 0.93]) in the morning and sleepier (0.52, 95% CI [0.11,0.90]) during daytime. The estimated effects of working a QR, for attention (95% CI [-6, 17]ms), incongruent stroop-trials (95% CI [-25, 68]ms), and the probability of misremembering words (95% CI[-0.02, 0.02], were small and overlapped zero.

Conclusion: Quick returns shorten sleep and are a source of fatigue among nurses. The sleep deprivation caused by QRs (compared with day-day transitions) were, however, approximately one hour and did not manifest in worse attention, conflict processing or memory impairments. The effects of QRs on subjective ratings of safety and performance will be analyzed and presented at the conference. This study indicates that the cognitive consequences of a single QR are not substantial, but future studies should investigate the effects of repeated QRs on cognitive performance and potential safety consequences.

As sleep restriction has negative effects on performance, ensuring sufficient sleep for shift workers is essential. Quick returns (< 11 h off between shifts) shorten sleep and are associated with increased fatigue and risk of accidents, but there is limited research on other aspects of cognitive performance and work performance. The aim of the present quasi-experimental field study was to investigate the effects of quick returns on objective and subjective measures of sleep, fatigue and cognitive performance. In total 36 newly graduated nurses were followed during two pre-scheduled work periods, with and without a quick return (evening–day–day vs. day–day–day). They kept diaries of sleep and work, wore actigraphy wristbands to record sleep and performed 3 × 3 min smartphone-based cognitive tests (simple reaction time, episodic memory and Stroop) several times daily. Quick returns were found to shorten sleep by 46 min on average, and participants felt less rested in the morning and sleepier throughout the day. Sleep fragmentation and sleep efficiency did not differ between conditions but participants reported poorer sleep quality. Although the nurses reported cognitive impairments after a quick return, the estimated effects on simple attention, episodic memory and Stroop were small and overlapped zero. There were also indications of lingering fatigue on the second day shift after a quick return, but estimates are uncertain. In sum, quick returns shorten sleep and decrease subjective alertness, which could contribute to increased fatigue-related risk at work, but people seem able to mobilise necessary resources to maintain performance on short cognitive tasks.

Study objectives: Short and long sleep duration as well as poor sleep quality have been linked to higher prevalence of metabolic disorders. However, it is still unclear how diverse sleep variables relate to different metabolic pathways. This study examines how different features of sleep health relate to serum metabolites.

Methods: The study used data from 197 healthy individuals aged 20–79 (Females n = 103) from the IronAge study performed at Karolinska Institutet in Sweden. Sleep variables were assessed with the Karolinska Sleep Questionnaire, where the following variables were computed: sleep duration, sleep debt, midpoint, social jetlag (i.e., the discrepancy between midpoint on free and workdays), napping frequency and sleep quality. Morning fasting blood samples were collected and ¹H NMR spectroscopy was utilized for metabolomic analysis. The metabolites were categorized according to their major metabolic pathways: amino acid, lipid, carbohydrate, energy and gut microbiota. Linear regressions were performed to examine the relationship between each sleep variable and metabolite.

Results: Sleep duration, midpoint of sleep on free days, social jetlag and chronotype associated with eight metabolites at a significance level of p<0.01. Notably, midpoint associated with most metabolites spanning multiple pathways. A later midpoint was associated with higher levels of metabolites in the lipid pathway, and lower levels in the amino acid and energy pathway.

Conclusion: These observations indicate that sleep timing features, midpoint and social jetlag, have a stronger relationship with morning metabolism than other sleep health dimensions. Following replication in larger samples, these complex relationships may hold potential for health promotion.

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.

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.