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Abstract Study Objectives Individual circadian type is a ubiquitous trait defining sleep, with eveningness often associated with poorer sleep and mental health than morningness. However, it is unknown whether COVID-19 pandemic has differentially affected sleep and mental health depending on the circadian type. Here, the differences in sleep and mental health between circadian types are examined globally before and during the COVID-19 pandemic. Methods The sample collected between May and August 2020 across 12 countries/regions consisted of 19 267 adults with information on their circadian type. Statistical analyses were performed by using Complex Sample procedures, stratified by country and weighted by the number of inhabitants in the country/area of interest and by the relative number of responders in that country/area. Results Evening-types had poorer mental health, well-being, and quality of life or health than other circadian types during the pandemic. Sleep–wake schedules were delayed especially on working days, and evening-types reported an increase in sleep duration. Sleep problems increased in all circadian types, but especially among evening-types, moderated by financial suffering and confinement. Intermediate-types were less vulnerable to sleep changes, although morningness protected from most sleep problems. These findings were confirmed after adjusting for age, sex, duration of the confinement, or socio-economic status during the pandemic. Conclusions These findings indicate an alarming increase in sleep and mental health problems, especially among evening-types as compared to other circadian types during the pandemic.

The aim of the paper is to review the current evidence on the impact of ‘the timing of energy intake’ on the risk of developing obesity and obesity-related metabolic diseases. The prevalence of obesity is currently increasing worldwide thus becoming a severe health burden for most countries. Indeed, obesity represents a risk factor for several non-communicable diseases such as cancer, type 2 diabetes, dyslipidaemia, CVD and overall mortality. In order to treat obesity, several pharmacological approaches have been developed and are indicated for subjects with obesity with a BMI ≥ 30 kg/m 2 or ≥ 27 kg/m 2 and obesity-related comorbidities. For severe obesity (BMI ≥ 40 kg/m 2 ), bariatric surgery represents a promising approach. The most common bariatric surgical procedures are represented by the Roux-en-Y gastric bypass, laparoscopic adjustable band, laparoscopic gastric sleeve and biliopancreatic diversion with duodenal switch. Both anti-obesity pharmacological and surgical treatments require change in lifestyle. When a nutritional plan is established, attention is usually paid to macronutrient composition and energy intake, while ‘the time of food’ is not taken into account. Chronotype, which is the attitude of a subject to carry out most of their daily activities in the first (morning chronotype) or second half (evening chronotype) of the day, has been reported to have a role in the pathogenesis of obesity and obesity-related cardiometabolic diseases as well as eating speed. Thus, adopting a physiological timing of energy intake could be an additional strategy to potentiate the current anti-obesity approaches.

Light spectra, an imperative zeitgeber, may differ in its chronobiological effects among chronotype ensuing differences in circadian pacesetting. With the increasing usage of colored lights in the environment, the effects of light wavelength on the electrical activity of the brain among chronotypes need to be investigated. Healthy participants (N=24) were recruited to morning, intermediate, and evening chronotype groups using the composite scale for morningness scores. They were exposed to randomized brief sessions of red, green, blue, and white light preceded by 15 min of darkness. EEG was recorded in all sessions. The power spectrum was estimated for alpha, beta, theta, and delta waves from different regions of the scalp and compared among the groups. The morning and evening chronotype had statistically significantly higher mean delta power than intermediate chronotype in colored light. Evening chronotype showed a statistically significantly higher mean beta power than the intermediate chronotype (p=0.013) in green light. Intermediate chronotype had statistically significantly higher mean alpha power than morning (p=0.029) and evening chronotype (p=0.009) in red light. The results show a significant effect of the spectral property of light on brain waves in chronotypes. The green light is more effective in alerting evening chronotypes. The finding of the present study may be applicable in research pertinent to brain imaging in chronotypes especially with red, green, and blue light exposure and chromotherapy-based interventions in affective and psychiatric conditions.

IntroductionMajor depressive disorder (MDD) constitutes a substantial global health burden, profoundly undermining psychosocial functioning and quality of life, and the persistent limitations of treatment efficacy—despite advances in neurobiology and pharmacotherapy—underscore its considerable clinical complexity. Recent research increasingly delineates the heterogeneity of depressive symptomatology, particularly emotional blunting, and emerging evidence further implicates metabolic and inflammatory pathways processes in shaping treatment response. Insulin resistance (IR), immune dysregulation, individual circadian preference, and trait-level vulnerabilities associated with neurodevelopmental or trauma-related characteristics may contribute to reduced responsiveness to standard therapies and limited adherence to antidepressant treatment. Taken together, these converging findings emphasize the need for individualized interventions rather than continued reliance on broad diagnostic categories.ObjectivesThe study consists of two phases with distinct hypotheses: phase I) evaluating emotional blunting along other clinical/psychopathological variables as potential predictors of treatment non-response to SSRI/SNRI in MDD, and phase II) assessing relationships between IR and treatment non-response to vortioxetine in MDD. Further exploratory objectives encompass assessment of: links between psychopathological and metabolic predictors of health status; longitudinal association between emotional blunting and both sexual and cognitive functioning.Materials and MethodsThe METOD study is an open, non-randomized two-phase observational study conducted in accordance with clinical standards and with all required ethical approvals. The protocol was prepared in line with STROBE recommendations. In Phase I, MDD patients meeting eligibility criteria and initiating antidepressant treatment with one of the first-line SSRIs or SNRIs are observed, whereas in Phase II, individuals showing an inadequate response are switched to vortioxetine as a second-line option. Validated clinical assessment tools are administered alongside anthropometric and laboratory evaluations.Expected Implications/SignificanceBy examining these interrelations within a naturalistic cohort treated in accordance with current clinical standards, this innovative study—with its strong emphasis on patient-reported outcomes—may increase insight into the lived experience of depression, enhance understanding of the pathophysiological mechanisms shaping its diverse symptomatology, and provide a foundation for more precisely targeted therapeutic approaches.

The aim of this study was to evaluate the association between chronotype, stress, sleep and social jetlag (SJL) in Bulgarian sports students. In total, 29 male and female university students were surveyed using the Horne-Ostberg morningness-eveningness questionnaire, smart watch for measuring the peripheral skin temperature, perceived stress scale (PSS), Pittsburgh sleep quality index (PSQI) and a self-report questionnaire to determine SJL. It was determined that 2 students were morning type (MT), 7 were evening type (ET) and 20 were intermediate type (IT). Temperature measurements confirmed that. Mann-Whitney U test showed an association between stress scores and gender groups, PSQI scores showed association with PSS groups, chronotype and SJL. Females were more stressed than males. Students with high SJL levels (n = 7) were ET (n = 5). In our sample ET (n = 7) were more than MT (n = 2). Usually athletes tend to be MT. Age has a great influence in chronotype expression. ET perceived more stress and experienced more frequent daytime dysfunction than MT and IT. Collectively, these results suggest that stress levels are higher when imbalance exists between more than one circadian rhythm disruption indicators. Also training schedules should be arranged when taking into account circadian preferences.

Individuals with severe mental illness (SMI) have increased risk of physical comorbidities, linked to worse outcomes such as greater psychopathology, frailty, and neurocognitive impairment. Mechanisms underlying this burden remain unclear. This study examined whether frailty and psychopathology predict evening chronotype, especially in SMI with comorbidities. A longitudinal study assessed 165 participants at two time points over one year: schizophrenia ( = 30), bipolar disorder ( = 42), major depressive disorder ( = 35), and healthy controls ( = 58). The SMI group ( = 107) was divided into SMI with comorbidities (SMI-C; = 47) and without (SMI; = 60). Measures included psychopathology, frailty, chronotype, neurocognitive and functional performance, and hematological biomarkers. Neurocognitive and functional impairments were greater in SMI groups than controls ( = 10.3-31.4; < 0.0001; η² = 0.12-0.34). The SMI-C group showed worse frailty than controls at T1 ( = 4.3; < 0.01; η² = 0.05) and than SMI at T2 ( = 8.5; < 0.0001; η² = 0.12), and elevated MCV/MCH ( = 3.8-9.4; < 0.05-0.0001; η² = 0.04-0.11). Chronotype distribution did not differ. Frailty and psychopathology predicted chronotype in SMI ( < 0.05-0.01); in controls, frailty and performance did so (p < 0.05). Psychopathological and hematological profiles are associated with chronotype and may help identify subgroups for chronobiology-informed interventions. These findings support more personalized treatment approaches.

Sleep has attracted extensive attention due to its significance in health. However, its association with erectile dysfunction (ED) is insufficiently investigated. To investigate the potential causal links between sleep traits (insomnia, sleep duration, and chronotype) and ED, this study was performed. The single-nucleotide polymorphisms (SNPs) associated with insomnia, sleep duration, and chronotype were retrieved from previous genome-wide association studies (GWAS). A conventional two-sample Mendelian randomization (MR) was used to estimate the causal links between sleep traits and ED. The summary statistics of ED were from individuals of European ancestry (6175 cases vs 217 630 controls). As shown by the random effect inverse-variance-weighting (IVW) estimator, genetically predicted insomnia was causally associated with a 1.15-fold risk of ED (95% confidence interval: 1.07-1.23, P < 0.001). Sleep duration and morningness were not causally associated with ED, as indicated by the IVW (all P > 0.05). These findings were consistent with the results of sensitivity analyses. Based on genetic data, this study provides causal evidence that genetically predicted insomnia increases the risk of ED, whereas sleep duration and chronotype do not.

Sleep and mental health are intrinsically intertwined, but not every individual with problems sleeping develops a mental health disorder. This study examined the association among chronotypes, resilience, sleep quality and mental health symptoms amongst otherwise healthy individuals. Two hundred adults ( M age  = 27.75 ± 5.11, 68% female) with no previous diagnosis of mental illness were recruited and filled in a set of questionnaires measuring chronotypes, sleep quality, depression and anxiety symptoms. The findings from the path analysis showed that the morning type had a statistically significant direct effect on a range of sleep quality indices. These included better subjective sleep quality, shortened sleep latency, and fewer daytime dysfunctions, as well as a higher level of resilience. However, it did not significantly affect depression and anxiety symptoms. In addition, the morning type had statistically significant indirect effects on a higher level of resilience and fewer depression and anxiety symptoms through the mediating effect of sleep quality indices. Findings from this study support that morning type is associated with better resilience and psychological health, which is mediated through better sleep quality.

Chronotypes reflect individual differences in the preference for wake and sleep times within a 24-hour period. They have been linked to emotional well-being, yet findings remain inconsistent, potentially due to variations in study populations, methodologies, and measures of emotional well-being. This study aimed to clarify the contribution of chronotypes to emotional well-being while controlling for demographic variables in a large cohort of 1,120 participants from the general population in Hungary. Emotional well-being was assessed using validated self-report measures, including the Brief Symptoms Inventory (BSI), Zung Self-Rating Depression Scale (ZSDS), State and Trait Anxiety Inventory-Trait (STAI-T), and Beck Hopelessness Scale (BHS). Chronotypes were determined using the Morningness-Eveningness Questionnaire (MEQ). Comprehensive stepwise regression analyses were performed to evaluate relationships between demographic factors, chronotypes, and emotional well-being. Statistical analyses revealed that individuals with evening chronotypes were more likely to report lower emotional well-being, even after adjusting for demographic factors such as age, gender, and socioeconomic status. Regression models demonstrated the unique contribution of chronotypes to emotional well-being, highlighting the vulnerability of evening types. These findings underscore the importance of considering chronotypes in understanding emotional health and suggest potential directions for chronotype-specific interventions to promote mental well-being.

Abstract Previous research has linked having an eveningness chronotype with a higher tolerance for night shift work, suggesting the ability to work nights without health consequences may partially depend upon having a circadian clock optimized for these times. As chronotypes entrain over time to environmental cues, it remains unclear whether higher relative eveningness among healthy night workers reflects a moderating or mediating effect of chronotype on health. We address these concerns conducting a genome-wide association study and utilizing a polygenic score (PGS) for eveningness as a time-invariant measure of chronotype. On a sample of 53 211 workers in the UK Biobank (2006–2018), we focus on the effects of night shift work on sleep duration, a channel through which night shift work adversely affects health. We ask whether a higher predisposition toward eveningness promotes night shift work tolerance. Results indicate that regular night shift work is associated with a 13-minute (3.5%) reduction in self-reported sleep per night relative to those who never work these hours (95% confidence interval [CI] = −17:01, −8:36). We find that eveningness has a strong protective effect on night workers: a one-SD increase in the PGS is associated with a 4-minute (28%) reduction in the night shift work sleep penalty per night (CI = 0:10, 7:04). This protective effect is pronounced for those working the longest hours. Consistent patterns are observed with an actigraphy-derived measure of sleep duration. These findings indicate that solutions to health consequences of night shift work should take individual differences in chronotype into account. Graphical Abstract Graphical Abstract