Physiology & Behavior

Courtship is an essential component of reproductive success for many species and many courtship behaviors, such as vocalization, are energetically demanding. In order to successfully balance investment in courtship with feeding and foraging, individuals must be aware of their current energy balance, and hormonal signals of energetic state have been found to influence social signal effort across a variety of species. Ghrelin is one hormone that plays an important role in regulating energy balance by signaling hunger and promoting feeding. Previous studies have investigated the role of ghrelin in courtship, aggression, and mating behavior. In this study, we build on prior work by investigating the effects of ghrelin on ultrasonic vocalizations (USV) and other courtship behaviors of male mice. We expand on previous research by observing ghrelin's effects over longer interactions, allowing us to understand how ghrelin impacts the dynamics of USV production over time. Our results show that while males initially vocally court females at a high rate regardless of treatment, ghrelin reduces overall USV production by increasing the rate of decline of vocalization. Surprisingly, despite its effects on vocal courtship, we found no significant differences in the production or timing of other, non-vocal, courtship behaviors. This study deepens our understanding of the role of hormones traditionally associated with controlling hunger and feeding in regulating social behaviors.

Ethanol is naturally present in nectar, but we still know little about how pollinators cope with long-term exposure to it at low concentrations. We exposed adult worker honeybees (Apis mellifera carnica Poll.) for eight days to diets containing 0, 0.1, 0.5, 1, 2, or 10% ethanol and measured survival, estimated intake, open-field locomotion, sting extension, whole-body trehalose, and hemolymph ethanol. Hemolymph ethanol was correlated with dietary concentration, attesting to internal exposure. Survival differed among diets, an effect which was driven by the difference between the 10% ethanol treatment and the control. Food intake was lowest at the 10% ethanol diet. There was also a modest increase in intake under the 0.1% ethanol treatment. In terms of locomotor features, bees moved less, moved more slowly, explored less space, covered shorter distances, and followed more tortuous paths after the 10% ethanol treatment. Neither sting extension nor trehalose were affected by dietary ethanol. The results showed no beneficial stimulation at lower concentrations. Instead, performance was endpoint-specific: at 0.1-2% ethanol in the diet, performance remained relatively stable across most parameters, whilst clear impairment was evident at 10%. These findings highlight resilience to repeated ethanol exposure in honeybees.

The satiety cascade includes post-prandial increases in plasma glucose and insulin, and changes in appetitive gut hormones, including decreases in orexigenic stomach-derived ghrelin, and increases in liver-foregut-derived LEAP2 hormone, a ghrelin antagonist. However, which contribute to post-prandial attenuation of eating behaviour with increasing preload meal size is unclear. In a randomised, single-blinded study, adults without obesity attended four visits, consuming 750mL liquid preloads 0, 600, 900, 1200 kcal, with assay of plasma glucose, acyl ghrelin (AG), LEAP2 and serum insulin over 0-3h with appetite ratings (n=17, 65 visits). At 2h a virtual portion size creation task measured desired food intake (n=15, 58 visits, after data exclusion), and at 3h an ad libitum meal measured actual food intake (n=11, 43 visits). The greater the pre-load meal size, the greater the post-prandial increase in plasma glucose and serum insulin, and greater the decrease in plasma AG and AG/LEAP2 ratio, associated with greater attenuation of eating behaviour (appetite ratings, desired/actual food intake). The strongest correlations of eating behaviour with blood measures were for serum insulin, plasma AG and AG/LEAP2 ratio, with weaker results for plasma glucose. Although there was a weak correlation of post-prandial plasma LEAP2 with pre-load meal size but not with eating behaviour. Post-prandial increases in serum insulin and decreases in plasma AG and AG/LEAP2 ratio appear part of the satiety cascade related to preload meal size in adults without obesity. Future studies should investigate potential mediation of satiety in this context via other appetitive gut hormones, and in obesity.

Ethanol occurs naturally in sugar-rich foods used by insects, but its effects in bees have been studied primarily in honeybees. We tested whether dietary ethanol affects survival and locomotor performance in workers of the bumblebee Bombus terrestris (L.). In the survival experiment, workers were fed ethanol (0, 1, or 10%) for 21 days; in the locomotor experiment, they were fed the same doses for one or seven days, after which we measured spontaneous movement using an open-field assay. We measured the proportion of time in movement, speed of movement, path meander (curviness), and arena exploration. The 10% ethanol concentration greatly increased the risk of mortality, whereas the estimated effect of 1% ethanol was smaller and statistically inconclusive. In terms of locomotion, the largest differences occurred after seven days of exposure to 10% ethanol. Workers in this treatment showed greater path meander and lower exploration than control workers. Speed was also lowest in this group. Evidence that exposure for seven days was worse than for one day at the same concentration was detected only for exploration. No clear locomotor effect was detected at 1% ethanol exposure. These findings provide comparative data on sustained ethanol exposure in bumblebees and show a strong concentration-dependent contrast, with substantial effects under high-concentration challenge but no clear effects on the measured endpoints at 1%.

Animals experience stressors in a variety of contexts that result in activation of neuroendocrine and cellular stress responses. Release of stress hormones can disrupt or restore redox homeostasis, and the resulting changes in oxidative states, physiology and behavior vary by an individuals stress coping style. However, oxidative stress can also directly modulate neuroendocrine stress signaling. To what extent individual differences in brain antioxidant levels alter behavioral stress levels is not well understood. The present study investigated how N-acetylcysteine amide (NACA), an antioxidant and glutamate-modulating compound, regulates stress behavior across zebrafish (Danio rerio) with different stress coping styles (proactive, reactive). Following 24-hour exposure to NACA or control conditions, we quantified individual and composite stress behaviors using a Light-Dark Test (LDT). As expected, both proactive fish and NACA-treated fish showed significantly lower stress behaviors compared to reactive and control animals, respectively. Notably, stress-reducing effects of NACA were only seen in those with a reactive stress coping style. Overall, our data suggest that antioxidant mechanisms (e.g., glutathione system) may be key in facilitating the distinct behavioral and physiological responses to stressors that characterize alternative stress coping styles. The results underscore how individual differences in stress coping style and redox state can influence behavioral responses to stress.

Rationale: Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have attracted interest for their effects on motivational processes beyond satiation and weight loss, including motivation for drug rewards. Reward-predictive cues can acquire motivational value and promote food- and drug-seeking, raising the possibility that GLP-1RAs affect intake by altering cue-motivated behavior. Preclinical studies report reduced food intake and responding for drug rewards following GLP-1RA treatment. However, many preclinical studies have used acute treatment; whereas, clinically, GLP1-RAs are administered as chronic treatments with dose escalation to mitigate adverse effects. Objectives: Using a modified Pavlovian conditioned approach (PavCA) paradigm, we directly compared the effects of acute and chronic semaglutide treatment on conditioned approach behavior elicited by cues predicting different magnitudes of palatable food reward in male and female rats. Results: Although both treatment regimens reduced body weight relative to vehicle treatment, chronic semaglutide increased, whereas acute semaglutide decreased, sign-tracking toward reward-associated cues. Rats exhibited greater sign-tracking toward cues predicting large versus small rewards, but semaglutide did not differentially alter this reward-magnitude effect. Acutely treated rats consumed fewer reward pellets and exhibited less food-cup activity during non-cue periods. These findings suggest that nonspecific behavioral suppression or malaise may have contributed to reduced responding after acute treatment. Conclusions: The effects of semaglutide on cue-motivated behavior depend on the treatment regimen. Acute-treatment studies should be interpreted cautiously because adverse or nonspecific effects may contribute to apparent reductions in motivation.

Planarians exhibit a variety of behaviors in response to external stimuli and have emerged as a promising animal model for studying the neural regulation of behavior. Although their feeding behavior has been well documented, robust experimental methods for quantifying their food intake remain limited. In this study, we developed a novel methodology for the quantitative assessment of feeding termed the "Complete-or- Partial (CoP) assay." This assay evaluates feeding responses as a binary outcome (complete consumption versus partial ingestion) in a volume-dependent manner at the individual level. Using this method, we examined the effects of food quality on feeding responses by comparing two distinct diets: a "basal diet" containing the minimum concentration of liver homogenate necessary to induce ingestion and support growth, and a "high-density diet" with a ten-fold higher concentration. The CoP assay enabled the robust estimation of food intake volume and successfully detected a significant overconsumption of the high-density diet compared to the basal diet, demonstrating that planarians regulate their food intake in a quality-dependent manner. Furthermore, individuals exhibiting partial ingestion did not immediately feed again even when presented with the same diet freshly prepared, indicating that they had reached satiety. Thus, we propose that the CoP assay offers a robust and scalable platform for evaluating both food intake volume and satiety status, providing a powerful tool to facilitate future molecular analyses of feeding regulation in planarians.

Animals differ in how they acquire and retain information, and modify their behavior while interacting with their environment. These differences have been linked to personality type, yet how personality type and sex influence reward-associated memory is not well understood. We investigated the effects of personality type, sex, days of conditioning, and food reward on learning and memory retention in zebrafish using the conditioned place preference paradigm. We conditioned zebrafish to associate a visual background with a food reward across eleven sessions and assessed memory recall seven days later by measuring duration, frequency of entry, and latency to first entry in the conditioned zone. We observed that bold fish had early conditioned zone engagement, whereas shy zebrafish gradually increased their behavior into the conditioned zone with repeated conditioning. With food reward, preference for the conditioned zone increased after 7 and 11 days post-conditioning relative to baseline. Seven days after the last conditioning with food reward, the preference for conditioned zone remained unchanged in shy fish. This suggests that shy fish retain the ability to recall the learned association for at least 7 days after conditioning. Overall, personality, food reward, and sex influence behavioral changes in food reward-associated cognition, with shy-treated males showing gradual increases in behavior into the conditioned zone. These findings suggest that personality and sex differences may depend on the nature and valence of the associative task to recall. Thus, this study emphasizes the importance of assessing memory retention alongside learning acquisition to understand the relationship between personality types and cognition.

Light influences mood in both clinical and experimental settings, yet it remains unclear how ambient light exposure relates to mood in daily life, which dimensions of mood are most sensitive to light and over what timescales these associations emerge. Here, we combined continuous personal light monitoring using wearable light sensors with repeated assessments of multiple dimensions of mood and affect, including self-reported mood ratings and cognitive measures of affective bias, alongside physiological monitoring in 49 healthy adults living under naturalistic conditions. Brighter light was consistently associated with more positive self-reported mood. Associations emerged over distinct temporal windows, with greater melanopic irradiance during the preceding 30 min associated with increased feelings of energy. Importantly, this association remained significant after accounting for alertness, physical activity and sleep-related covariates, suggesting that it is not solely explained by the established alerting effects of light. In contrast, several positive mood dimensions, including happiness, feeling accompanied, enjoyment, motivation and relaxation, were associated with light accumulated over longer periods (60-240 min). Furthermore, happiness, feeling accompanied, enjoyment and relaxation, but not energy, were also associated with greater cumulative daily exposure to light above 250 lux melanopic equivalent daylight illuminance (EDI), a threshold proposed to support healthy daytime light exposure. Behavioural measures of affective bias showed no robust associations with light exposure. Together, these findings indicate that everyday light exposure is associated with distinct dimensions of mood over different timescales, highlighting a complex relationship between light and affect in daily life. Significance StatementLight is a promising target for improving mental health, yet little is known about how everyday light exposure relates to mood outside laboratory and clinical settings. Using wearable light sensors and repeated mood assessments in healthy adults living under naturalistic conditions, we show that different dimensions of mood are linked to light exposure over distinct timescales, from recent exposure to cumulative light history. Importantly, the association between recent light exposure and feelings of energy remained independent of physical activity and sleep-related factors. These findings demonstrate that effects of light on mood are dynamic and multidimensional, highlighting the need to move beyond simple measures of total light exposure and informing future efforts to design healthier light environments that support emotional wellbeing.

Traditionally, complex behavioral tasks in mice have relied upon water restriction as an external motivator to increase task engagement. However, citric acid (CA) water, the technique whereby water is given ad libitum but made sour by the addition of CA, has emerged as an alternative to typical water restriction. Evidence suggests CA water can effectively motivate task performance while improving animal welfare in alignment with the 3Rs of animal research and reducing experimenter labor. While promising, the applicability of CA water in mice remains incompletely characterized with higher concentrations only tested in rats and "ramping" schedules, where mice progress to increasingly higher concentrations, indirectly examined. Here, we evaluate four CA concentration/schedule combinations for their effects on mouse health (weight changes, home cage behaviors, fecal counts) and motivation to drink regular water (lick counts, drinking behaviors) in female and male C57BL/6J mice. We find that a schedule ramping from 1% to 2% CA after one week is the easiest for mice to adapt to and sustained 2% CA use maintains robust lick counts for at least 5 weeks. Additionally, CA has been directly characterized for wheel-turning and touchscreen tasks, but not virtual reality (VR) tasks, an increasingly popular class of behavioral experiments. Therefore, we also assess how 2% CA affects motivation and task performance in two VR treadmill tasks (running and stopping task). We find that CA water does not improve task performance above that of mice given regular water, but does limit competing motivations and produce more uniform, reward-motivated behavior.

Stress is a physiological, adaptive, and preliminary response of the organism to situations of threats and instability caused by environmental and psychological stressors. The chronicity and predictability of stressors are important variables in determining neurobehavioral outcomes. While unpredictable chronic stress (UCS) protocols typically induce depressive-like phenotypes in rodents, in zebrafish the effects of these protocols are assessed using anxiety-like outcomes. This study aimed to analyze the effects of an unpredictable UCS on depressive-type behavioral parameters and brain lipid peroxidation in zebrafish. A 14-day UCS protocol was used, with 10 different types of stressors administered twice daily in a random manner, using draws, for greater unpredictability. Animals underwent the Novel Tank Test (anxiety-like outcome) and the Social Preference Test (depressive-like outcome) 24 hours after the end of the UCS protocol. Biochemical data were collected using a thiobarbituric acid reactive substances (TBARS) assay to quantify malondialdehyde (MDA), an indicator of lipid peroxidation. The findings suggest that prolonged exposure to stressors causes damage to the organism, with increased anxiety and decreased social preference, highlighting zebrafish as an efficient model in the investigation of the neurobiological and neuropathological mechanisms of stress.

Synchrony between time-of-day and food intake is critical for maintaining homeostasis while desynchrony between these cues caused by repeated bouts of mistimed eating (ME) is profoundly disruptive to organismal health. However, it is unknown whether the same is true for a single bout of ME. While it is generally accepted that mammals recover quickly from acute alterations in feeding schedule and that chrono-disruption requires chronic, repeated changes, there have been no dedicated investigations of acute ME to suggest otherwise. Therefore, we exposed female and male C57Bl6/J mice to a single bout of ME or timed eating (TE) and continuously measured metabolic and behavioral responses for five days. A single bout of ME was sufficient to disrupt the daily rhythms of metabolic and behavioral outcomes for several days. Energy expenditure and wheel running activity were disrupted and light:dark variation in food intake and macronutrient utilization were altered for several days. Finally, ME changed the amount of time spent resting in for several days post-ME. The TE paradigm disrupted macronutrient utilization for two days but otherwise had no effect on metabolism or behavior. Our results demonstrate that one instance of ME alone has lasting impacts on daily rhythmicity and is an understudied source of circadian disruption.

Healthy lifestyle habits are a key pillar of physical, psychological, and social well-being, yet university years are often marked by declines in sleep quality, physical activity, and other health behaviors that may affect academic performance. This cross-sectional study examined these associations in 390 Spanish university students, assessed via an online and in-person questionnaire covering academic trajectory (grade point average, credits passed, curricular progression), sleep quality (PSQI), physical activity (IPAQ), tobacco use, Body Mass Index (BMI), and sociodemographic data. Bivariate associations were tested with chi-square, Pearson correlation, t-tests, and ANOVA, followed by generalized linear models for significant variables. Sports participation, but not IPAQ-measured physical activity, was significantly associated with academic progression, defined as advancing one grade level per year. Sleep indicators showed mixed, partly counterintuitive associations: poorer nocturnal sleep was linked to better progression, whereas better sleep quality predicted a higher percentage of credits completed. BMI was a modest positive predictor of credit completion, and underweight students performed significantly worse than overweight or obese peers. Tobacco use showed no significant associations. These findings suggest that sleep-related behaviors, sports participation, and, to a lesser extent, BMI, are relevant correlates of academic progress, supporting university health policies addressing sleep, physical activity, and nutrition.

Operant paradigms are powerful tools to quantify motivation and reward. Traditionally, operant conditioning research has been limited to food and drug reinforcers. Recent advances in commercially available operant equipment, however, allow for the quantification of social motivation. These operant assays are an improvement over commonly used social preference tasks, as they enable direct measurement of the effort and motivation driving social behavior. Based on a design by Venniro et al. (2020), the MedPC social operant boxes modify the traditional operant box setup for social interactions. The experimental rat can lever-press to raise a door for an interaction with a target rat behind a porous barrier. These social operant boxes have been widely adapted to test social behavior in adult and adolescent rodents and investigate how a range of conditions (e.g. stress, drug taking, etc.) affect social motivation. However, there is a gap in assessing maternal motivation for pups during the postpartum period, despite ample evidence that postpartum social behavior is highly relevant for offspring health outcomes. Here, we detail 3D-printed modifications to the standard Med PC social operant boxes to adapt the social target chamber to safely house neonatal pups. We have also developed testing protocols to assess motivation during the limited postpartum period. These data demonstrate that, with simple modifications to social operant chambers and testing protocols, the field can implement advanced behavioral approaches to directly assess maternal motivation.

While hamsters are commonly housed in groups within pet shops in Japan, small cages are often thought to restrict their physical activity, leading to arguments that larger cages should be provided. Although previous research has investigated how cage size and running wheel availability influence activity levels in individually housed hamsters, no studies to date have examined these specific effects in a social housing context. Therefore, this study investigated how cage size and the presence of a running wheel affect the activity levels of individual hamsters using the group-housing conditions with five hamsters. Video recordings were captured for 24 hours across four distinct cage environments using a camera installed directly above each cage. From these recordings, the distances traveled on both the cage floor and the running wheel were calculated for each hamster and statistically analyzed. The results revealed that overall activity levels were significantly higher in cages equipped with a running wheel than in those without. Although cage size did not yield a statistically significant difference, a marginal trend toward higher activity in larger cages was observed.

We previously reported, using in-vivo fiber photometry, that operant responding reinforced by access to a peer (social self-administration) is associated with phasic dopamine increases in nucleus accumbens (NAc) core following lever insertion (reward-availability cue) and gradual increases preceding lever-pressing. Here, we sought to replicate these findings and determine whether dopamine signals (1) generalize to responding for high-carbohydrate palatable food, (2) show opposite patterns during negative reinforcement (shock avoidance/escape), and (3) depend on whether reinforcers are experienced alone or together. We trained rats (n=11; 6 females) to lever-press for access to a same-sex peer (15 s/trial) and palatable food (45-mg pellet/trial), followed by shock avoidance/escape (0.18-0.26 mA). After training, we expressed the dopamine sensor GRAB-DA2m and implanted optic fibers into NAc core. We measured dopamine activity during sessions with either one- or three-reinforcers. During social self-administration, dopamine activity showed phasic increases following lever insertion and gradual increases preceding lever-pressing; responses were moderately greater during sessions with all three reinforcers. Palatable food self-administration showed a similar pattern, but responses were approximately twofold greater during single-reinforcer sessions. During shock avoidance/escape, dopamine activity showed phasic decreases at warning onset, lever insertion, and shock onset; responses were also greater during single-reinforcer sessions. Results suggest that NAc core dopamine signaling distinguishes positive from negative reinforcement and is modulated by reinforcer availability. Compared with single-reinforcer sessions, dopamine responses during food self-administration and shock avoidance/escape were reduced during sessions with all three reinforcers, whereas responses during social self-administration modestly increased. Significance statementNucleus accumbens (NAc) dopamine is critical for processing the valence of positive reinforcers, whereas its role in negative reinforcement is less well understood. Here, we extended our prior work on operant social self-administration to determine whether these findings generalize to food reinforcement, show the opposite pattern during operant negative reinforcement (shock avoidance/escape), and depend on whether reinforcers are experienced alone or together. Results suggest that NAc core dopamine activity differentiates positive and negative reinforcement and is modulated by the presence of other available reinforcers. Specifically, dopamine responses during food self-administration and shock avoidance/escape were reduced when all three reinforcers were available together compared with when each reinforcer was experienced alone, whereas responses during social self-administration showed the opposite pattern.

Music is a central component of psychedelic settings, yet little experimental work has examined how psilocybin and musical composition influence music-evoked emotional responses in healthy volunteers. This exploratory, double-blind, placebo-controlled study assessed these effects during the plateau phase of psilocybin and the corresponding time window in placebo sessions following oral administration of psilocybin (0.26 mg/kg) or placebo. The study consisted of two parts. In Part 1 (n = 19), a pilot stage, the first half of participants rated music-induced affective valence for eight compositions representing different genres/subgenres (Rock/Punk, Metal/Industrial Metal, Metal/Industrial Metal, Classical/Baroque, Electronic/Dub, Folk/Nordic Folk, Electronic/Techno, Electronic/Trance, Electronic/Psytrance) using a visual analogue scale (VAS). Based on Part 1, the classical composition with the highest overall affective valence and the psytrance composition with the largest psilocybin-placebo contrast (i.e., the composition most responsive to psilocybin) were selected for Part 2 (n = 17), in which the second half of participants assessed emotional responses to music using the Geneva Emotional Music Scale (GEMS-9). Psilocybin increased wonder, transcendence, and joyful activation across both contrasting compositions. Relative to each other, the classical composition elicited greater peacefulness, tenderness, and nostalgia, whereas the psytrance composition elicited greater tension across both psilocybin and placebo conditions. A composition x condition interaction was observed for sadness: under psilocybin, sadness increased during the classical composition and decreased during the psytrance composition. These findings suggest that psilocybin and contrasting musical compositions independently influence different aspects of music-evoked emotional responses, with limited interaction effects, and point to potential implications for protocol design and music selection in psychedelic settings.

Dairy-free foods must reproduce diverse functions of dairy, from foam stabilization in a latte to acid-gel structure in yogurt and melt-stretch behavior in mozzarella. Public consumer benchmarks rarely compare these categories under a common protocol. Here we analyze data from the NECTAR Taste of the Industry 2026 study, a blinded, randomized, in-person evaluation of commercial dairy-free products and dairy benchmarks. The full study included 2,183 consumers and 112 products across ten categories, with 3,220 product evaluations and 79,027 recorded survey responses, including 35,762 product-linked responses. The ten categories included barista milk, butter, cheddar, cream cheese, creamer, ice cream, fluid milk, mozzarella, sour cream, and Greek style yogurt. Within each category, we compare a dairy benchmark with the dairy-free product selected post hoc as the category leader. Participants rated overall liking, flavor, texture and mouthfeel, appearance, similarity to dairy, and purchase intent on seven-point scales and completed check-all-that-apply questions. In exploratory category-specific equivalence tests using a chosen margin of {+/-}0.05 points, barista milk, creamer, and fluid milk meet this margin. Mozzarella has the largest paired deficit of -1.46 points (unadjusted, p < 0.001), followed by Greek style yogurt and butter; all three remain significant after Holm correction across the ten primary comparisons. Descriptive penalty analysis associates off-flavor, artificial or chemical notes, stale or cardboard notes, bitter taste, and lingering aftertaste with the largest reductions in liking. Together, these results establish the first open sensory benchmark for dairy and dairy-free products, demonstrate that sensory parity is already achievable in several beverage categories, and identify the product categories and sensory attributes that offer the greatest opportunities for future innovation.

RationaleThe -opioid receptor (MOR) is widely expressed across tissues and plays crucial roles in pain and stress responses, social behaviour, and immune regulation. Recent evidence indicates seasonal variation in in vivo MOR signalling; for example, short photoperiods are associated with reduced central MOR availability, increased MOR expression in brown adipose tissue (BAT), and strengthened brain-BAT interactions. However, despite this coupling with photoperiod, it remains unclear whether static daylength and dynamically changing photoperiods exert distinct effects, as adaptation to photoperiod transitions may itself induce stress-related modulation of the MOR system. Elucidating how seasonal, stress-related adaptations influence MOR signalling is essential for advancing our understanding of seasonal fluctuations in mood and stress regulation. MethodsWe compared rats housed under seasonal photoperiod cycling with those maintained under constant photoperiod conditions, using ex vivo radioligand binding to directly assess MOR density in central and peripheral tissues. ResultsRats exposed to seasonal photoperiod cycling showed markedly reduced inter-individual variability in MOR density in both the brain (including the cerebellum and striatum) and peripheral tissues (adrenal glands), whereas no tissues exhibited substantially increased variability. ConclusionsThese findings demonstrate that seasonal photoperiod cycling stabilizes MOR dynamics at the population level, suggesting stress-related synchronization of MOR signalling. The findings deepen our understanding of seasonal effects on endogenous MOR signalling, and further underscore the role of seasonal light variation in modulating mood-related processes.

Sleep is proposed to have a beneficial effect on the consolidation of memories and gist abstraction in adults. For children, gist abstraction is of special relevance to transform new information from social and emotional contexts into stable representations. This study investigated the effect of sleep on emotional and social recognition and gist abstraction on N=34 typically developing children assessed in a sleep and a wake condition. In an emotional memory task, reward-associated stimuli were presented, while a social memory task used face-stimuli to implement social acceptance or rejection from peers. Both paradigms relied on a hidden rule to be abstracted. In general, children were able to remember emotional and social stimuli and to abstract gist information. With respect to sleep, we found a beneficial effect of sleep on the recognition of emotional stimuli but no sleep-dependent enhancement for either social recognition or emotional or social gist abstraction. Overall, our results indicate, that sleep-dependent recognition might depend on the type of memory task. Furthermore, nighttime sleep as compared to daytime wakefulness has no differential influence on gist abstraction in children as assessed in our paradigms, contrasting previous results found in adults.