Short sleep duration is associated with higher risk of central obesity in adults: A systematic review and meta-analysis of prospective cohort studies.

Background and Objective: The relationship between sleep duration and obesity has been the focus of numerous investigations. This systematic review and meta-analysis of prospective cohort studies aimed to assess the relationship between sleep duration, abdominal obesity, and body composition. Methods: PubMed, Scopus, and Web of Science were searched until February 2024. Cohort studies that assessed the relationship between sleep duration at night and central obesity measures or body composition indices in adults were included. The quality of studies was assessed using the Newcastle-Ottawa scale. Random-effects meta-analysis was conducted on studies that reported risk ratio (RR) and 95% confidence intervals (CIs). Results: Eighteen studies were eligible to be included. Eleven out of the 18 studies were not included in the analysis as 10 studies did not report RR, and in one study, the definition of short and normal sleep duration was different from others. The results of the meta-analysis indicated that short sleep duration was significantly associated with abdominal obesity (RR = 1.08; 95% CI: 1.04-1.12; I 2 = 49.1%, n = 7), but long sleep duration was not (RR = 1.02; 95% CI: 0.83-1.24; I 2 = 98.2%, n = 6). Conclusions: Short sleep duration was associated with a slightly higher risk of central obesity, while long sleep duration was not.

The Relationship between Body Mass Index, Body Dissatisfaction and Mood Symptoms in Pregnant Women.

Background: High body mass and adiposity during pregnancy can contribute to psychological distress, and body dissatisfaction may be a potential underlying mechanism of this association. Objective. This study aimed to evaluate the mediational role of body dissatisfaction in the relationship between body mass index (BMI) and depressive and anxious symptoms, respectively. Methods: Given the cross-sectional design of this study, two alternative models were investigated, positing that BMI was related to depressive (Model 1a) and anxious symptoms (Model 2a), which, in turn, predicted body dissatisfaction. Seventy-two pregnant women in the third trimester of pregnancy completed the Body Image Disturbance Questionnaire, the Beck Depression Inventory-II and the State-Trait Anxiety Inventory, as well as a demographic form assessing their BMI. Results: As hypothesized, body dissatisfaction mediated the relationship between BMI and psychopathological symptoms. Moreover, the alternative models of reverse mediation were also significant, suggesting that psychopathological symptoms mediated the relationship between BMI and body dissatisfaction. Findings from both the hypothesized and alternative models suggested that, on the one hand, higher distress symptoms associated with body dissatisfaction would result from high BMI and, on the other hand, that body dissatisfaction may result from the effect of BMI on distress symptoms. Conclusions: The present study suggests that body image theory and practice should be implemented by the inclusion of evidence-based clinical interventions for promoting psychological well-being during the antenatal period.

Inflammation as a mediator between adverse childhood experiences and adult depression: A meta-analytic structural equation model.

Exposure to adverse childhood experiences (ACEs) confers a higher risk of developing depression in adulthood, yet the mediation of inflammation remains under debate. To test this model, we conducted a systematic review and two-stage structural equation modelling meta-analysis of studies reporting correlations between ACEs before age 18, inflammatory markers and depression severity in adulthood. Scopus, Pubmed, Medline, PsycInfo, and CINAHL were searched up to 2 October 2023. Twenty-two studies reporting data on C-reactive protein (CRP, n = 12,935), interleukin-6 (IL-6, n = 4108), tumour necrosis factor-α (TNF-α, n = 2256) and composite measures of inflammation (n = 1674) were included. Unadjusted models revealed that CRP (ß = 0.003, 95 % LBCI 0.0002 to 0.0068), IL-6 (ß = 0.003, 95 % LBCI 0.001 to 0.006), and composite inflammation (ß = 0.009, 95 % LBCI 0.004 to 0.018) significantly mediated the association between ACEs and adult depression. The mediation effects no longer survived after adjusting for BMI; however, a serial mediation model revealed that BMI and IL-6 sequentially mediated the association between ACEs and depression (ß = 0.002, 95 % LBCI 0.0005 to 0.0046), accounting for 14.59 % and 9.94 % of the variance of IL-6 and depressive symptoms, respectively. Due to the cross-sectional nature of assessment of inflammation and depression findings should be approached with caution; however, results suggest that complex interactions of psychoneuroimmunological and metabolic factors underlie the association between ACEs and adulthood depression.

Associations between immune biomarkers and symptoms of anxiety, depression, and insomnia in paediatric inflammatory bowel disease: A preliminary longitudinal analysis.

Innate immunity may influence the onset of affective symptoms and alter sleep patterns in chronic inflammatory conditions. Here, we tested the prospective associations between baseline serum C-reactive protein (CRP), albumin, and CRP/albumin ratio (CAR, i.e., an emerging biomarker of disease activity), and self-reported symptoms of anxiety, depression, and insomnia at 1-year follow up in paediatric inflammatory bowel disease (n = 17). After controlling for baseline values, CAR (ρ = 0.591, p = 0.026) predicted anxiety symptoms, while albumin predicted both anxiety (ρ = -0.687, p = 0.007) and insomnia symptoms (ρ = -0.648, p = 0.012). Current findings preliminarily suggest that inflammation may influence anxiety and sleep disturbance in paediatric IBD.

Body shaming and internalized weight bias as potential precursors of eating disorders in adolescents.

Introduction: Body shaming (BS) is a growing phenomenon within the school context, especially among adolescents. Recently, it has been described as an unrepeated act in which a person expresses unsolicited, mostly negative comments about an individual's body. The targeted person perceives these comments as negative, offensive or body shame-inducing. Empirical evidence also suggests that body weight is the most common reason that youths are teased and bullied. Indeed, weight stigma, described as bias or discriminatory behaviors, attitudes, feelings, and thinking about individuals, because of their weight, can lead to weight-based discrimination and victimization. Preliminary evidence suggests that BS and weight stigma have negative effects on psychological health both in the short and long term. In the delicate stage of adolescence development and pubertal maturation, BS experiences can be highly prevalent and it can lead to adverse outcomes such as eating disorders (ED). However, prevalence data in the Italian context are still lacking. Methods: The study aims to estimate weight-related BS perceived by different sources (i.e., peers and family members) and their associations with public and internalized weight bias, body mass index (BMI), body dissatisfaction, and ED symptoms. A sample of 919 high school students (Mage = 15.97, SD = 1.58; 57.1% boys) completed a battery of self-report questionnaires assessing these variables. Results: One in four students reported experiences of weight-related BS by peers or family members. A total of 37% reported having at least one BS experience in a lifetime. Higher scores of ED symptoms, body dissatisfaction, and weight bias were reported by adolescents who experienced BS, especially females. Among overweight participants, results showed that internalized weight bias partially mediated the relationship between BS by family members and ED symptoms and fully mediated the relationship between BS by peers and ED symptoms, after controlling for age, sex and BMI. Discussion: These findings, despite their cross-sectional nature, add an important contribution to the creation of quantitative empirical evidence on the phenomenon of BS. Its role in explaining eating disorders, both alone and with the mediation of internalized weight stigma has been first proved and needs to be confirmed by longitudinal results.

Inflammation as an aetiological trigger for depressive symptoms in a prospective cohort of patients with inflammatory bowel disease.

OBJECTIVE: Inflammatory bowel disease (IBD) is often comorbid with mood disorders and depressive symptoms. The aetiology of depressive symptoms in IBD, however, remains largely unknown. Consistent with the inflammatory hypothesis of depression, the aim of this study was to explore the prospective associations between inflammatory biomarkers and depressive symptoms in a cohort of IBD patients with and without a previous clinical diagnosis of mood disorder. METHOD: IBD clinical activity was determined using the Harvey-Bradshaw Index for CD and the Partial Mayo score for UC; serum C-reactive protein (CRP) and faecal calprotectin (fCAL) were used as biomarkers of systemic and intestinal inflammation, respectively. Participants were administered the Hospital Anxiety and Depression Scale-depression (HADS-D) at baseline and 1-year follow-up. RESULTS: Eighty-four participants (50 ± 16 years; 75% UC and 25% CD) were included in the main analyses. Longitudinal moderated regression models showed that baseline CRP significantly predicted follow-up HADS-D scores among individuals with a previous mood disorder diagnosis (ß = 0.843, p < .001), but not among individuals without (ß = -0.013, p = .896), after controlling for baseline HADS-D scores, body mass index, IBD phenotype, sex, and perceived stress. Likely due to lower power, results on FCAL (n = 31) were not statistically significant. CONCLUSION: This study suggests that IBD patients with previous diagnosis of mood disorder may be at higher risk of inflammation-related depressive symptoms.

Bullying Victimization and Adolescent Depression, Anxiety and Stress: The Mediation of Cognitive Emotion Regulation.

BACKGROUND: Existing research has revealed a robust association between bullying victimization and psychological distress, but less is known about the underlying mechanism of this link. cognitive emotion regulation (CER) strategies could be a potential mediator. The current study examined the role of functional and dysfunctional CER strategies as potential mediators of the association between bullying victimization and depression, anxiety, and stress symptoms among 638 high school students (53.9% boys; Mean age = 15.65, SD = 1.32). METHOD: Participants completed a series of questionnaires assessing bullying victimization (Olweus Bully/Victim Questionnaire), CER strategies (CERQ-18), and symptoms of depression, anxiety, and stress (DASS-21). The indirect relationships between bullying victimization and psychopathological symptoms via functional and dysfunctional CER strategies were tested through structural equation modeling. RESULTS: Dysfunctional CER strategies mediated the impact of bullying victimization on depression, anxiety, and stress. In contrast, bullying victimization did not significantly influence functional CER strategies. CONCLUSIONS: The findings provide additional support for the detrimental role of bullying victimization on mental distress, also suggesting that this effect is not only direct, but indirect is well. These results are particularly relevant in light of the absence of mediation by protective factors such as the use of positive emotion regulation strategies.

The Sleepiness-Depression Link in Obstructive Sleep Apnea: Preliminary Results on the Mediation of Impulsivity.

BACKGROUND: Emotional impulsivity has been found to be relevant in explaining the association between sleep problems and depressive symptoms, suggesting the potential role of impulsivity as a key underlying mechanism of this link. The objective of this study was to take a preliminary step in understanding the mediating role of impulsivity in the relation between excessive daytime sleepiness (EDS) and depression in patients with obstructive sleep apnea syndrome (OSAS) and to compare psychological and demographic characteristics between different levels of daytime sleepiness. METHODS: A total of 138 patients with OSAS underwent polygraphic cardiorespiratory monitoring and completed a series of questionnaires investigating perceived sleepiness, depression, impulsivity, and other psychological characteristics. A mediational model was tested in order to assess whether impulsivity mediated the relation between sleepiness and depressive symptoms while controlling for the effects of age, sex, BMI, and oxygen saturation parameters. RESULTS: the mediation model showed that there was a significant indirect effect of impulsivity in the sleepiness-depression link (αß = 0.084 [0.0243-0.1617]). CONCLUSIONS: The here-presented results showed that the sleepiness-depression link is not direct as previous studies asserted, but instead it may be better explained by impulsivity. Research and practical implications are discussed.

Psychological Counseling among University Students Worldwide: A Systematic Review.

University counseling services (UCSs) are actively involved in mental health assessment and in supplying interventions aimed at preventing, facing and possibly overcoming psychological problems. However, we do not have a global overview of psychological counseling among universities. This systematic review aims at reviewing the literature on university psychological counseling, including articles documenting: (1) mental health and attitudes regarding help-seeking behaviors and UCSs among university students or counselors, (2) the description of protocols/services among UCSs, (3) the efficacy of psychological counseling/interventions among university students (both face-to-face and internet-delivered interventions). The study followed PRISMA guidelines and was registered on PROSPERO. After defining inclusion and exclusion criteria, a literature search was conducted, identifying 7085 records. Finally, 152 articles met the review eligibility criteria and were included in the qualitative synthesis. Results are divided into seven thematic topics that emerged during the analysis of the literature. The results mainly showed that face-to-face and web-based counseling/psychological interventions improve university students' mental health. Cross-sectional studies showed that many biases exist toward help-seeking behaviors, especially among international students. Both students and counselors must strive to overcome cultural barriers. Available resources for UCSs are scarce and need to be strengthened, as well as efficacy studies through randomized clinical trials.

Cross-cultural adaptation and psychometric properties of the Italian version of the Orthorexia Nervosa Inventory (ONI).

BACKGROUND: Orthorexia Nervosa (ON) is an emerging clinical condition characterized by a pathological fixation with healthy eating. Recently, the Orthorexia Nervosa Inventory (ONI) has emerged as a promising tool for assessing orthorexic tendencies and behaviours, aiming to overcome the well-established limitations of existing measures for ON. The present study aimed to examine the psychometric properties of the Italian version of the ONI. METHODS: A total of 879 participants (Mage = 33.22 years, SD = 9.19; 56.9% females) completed the ONI along with the Düsseldorf Orthorexia Scale (DOS), measures of disordered eating, obsessive-compulsive symptoms (OCD), and psychosocial impairment. To establish the factorial validity of the ONI, a competing measurement modeling approach was employed by comparing standard confirmatory factor analytic (CFA) with exploratory structural equation modeling (ESEM) solutions. Model-based omega coefficients were computed to examine the internal consistency of the scale. Factorial invariance tests across gender were conducted within a multi-group framework. RESULTS: A three-factor first-order ESEM solution provided the best and most parsimonious representation of the data: χ2(207) = 558.641, p < .001, RMSEA = 0.044 (90% CI 0.040-0.048), CFI = 0.976, TLI = 0.968, SRMR = 0.036. The three latent dimensions, labelled behaviors, emotions, and impairments, showed excellent internal consistency (ω > 0.88). Furthermore, ONI scores were found to be positively correlated with DOS scores, disordered eating, OCD symptoms, and psychosocial impairment, supporting its convergent and criterion validity. Eventually, the ONI was factorially invariant across gender. CONCLUSIONS: Overall, the present study provides evidence for the satisfactory psychometric properties of the ONI in the Italian context, endorsing its use in both clinical and research settings.

Orthorexia Nervosa (ON) is a clinical condition characterized by a pathological fixation with healthy eating. The Orthorexia Nervosa Inventory (ONI) is a recently developed instrument to assess ON behaviours and tendencies. However, the scale has not yet been adapted for the Italian cultural context. To fill this gap, the present investigation aimed to translate the ONI into Italian and examine its psychometric properties on a community sample. The study involved 879 participants (M_age = 33.22 years, SD = 9.19; 56.9% females) who completed a series of self-report questionnaires. Findings revealed that the ONI items reflect  three latent dimensions: behaviours and preoccupation with healthy eating; physical and psychosocial impairments; and emotional distress. Importantly, the present study accrued substantial evidence for the internal consistency and criterion validity of the scale, the latter supported by significant correlations with measures of disordered eating, obsessive-compulsive symptoms, and psychosocial impairment. Overall, these findings endorse the use of the Italian version of the ONI for clinical and research practices.

The relationship between internalized weight stigma and physical and mental health-related quality of life in a large sample of women: a structural equation modeling analysis.

PURPOSE: Health-related quality of life (HRQOL) refers to an individual's perception of their physical and mental health status over time. Although emerging evidence has documented a negative association between weight stigma (i.e., negative weight-related attitudes and beliefs towards individuals with overweight or obesity) and mental HRQOL, its influence on physical HRQOL still needs to be fully clarified. This study aims to investigate the impact of internalized weight stigma on mental and physical HRQOL by employing a structural equation modeling (SEM) approach. METHODS: The Short Form Health Survey 36 (SF-36) and the Weight Bias Internalization Scale (WBIS) were administered to a sample of 4450 women aged 18-71 (Mage = 33.91 years, SD = 9.56) who self-identified in a condition of overweight or obesity (MBMI = 28.54 kg/m2; SD = 5.86). Confirmatory factor analysis (CFA) was conducted to assess the dimensionality of the scales before testing the proposed structural model. RESULTS: After establishing the adequacy of the measurement model, SEM results revealed that internalized weight stigma was significantly and negatively associated with both mental (ß = - 0.617; p < 0.001) and physical (ß = - 0.355, p < 0.001) HRQOL. CONCLUSION: These findings offer additional support to prior research by confirming the association between weight stigma and mental HRQOL. Moreover, this study contributes to the existing literature by strengthening and extending these associations to the physical HRQOL domain. Although this study is cross-sectional in nature, it benefits from a large sample of women and the use of SEM, which offers advantages over traditional multivariate techniques, e.g., by explicitly accounting for measurement error. LEVEL OF EVIDENCE: Level V, descriptive cross-sectional study.

Differential Associations of Cognitive Emotion Regulation Strategies with Depression, Anxiety, and Insomnia in Adolescence and Early Adulthood.

While difficulties with emotion regulation (ER) are consistently linked to poor mental health in adulthood, findings in adolescence have been more mixed. Cognitive ER strategies, which involve the ability to manage emotions through mental processes, may be particularly important during different stages of development due to age-specific adjustments. We conducted two exploratory and cross-sectional studies to examine the relationships between cognitive ER strategies and mental health (i.e., depressive, anxiety, and insomnia symptoms) in two samples: 431 young adults (Mage = 20.66 ± 2.21; 70% women and 30% men) and 271 adolescents (Mage = 14.80 ± 0.0.59; 44.6% girls and 55.4% boys). The participants completed a group of questionnaires, including the Cognitive Emotion Regulation Questionnaire, the Insomnia Severity Index, the Beck Depression Inventory-II, the State-Trait Anxiety Inventory, and the Youth Self Report. We employed hierarchical multiple regressions to assess the unique contribution of cognitive ER strategies to mental health outcomes. Maladaptive strategies (such as rumination and catastrophizing) were consistently associated with impaired mental health in both samples, while adaptive strategies (such as positive refocusing and positive reappraisal) were only associated with better mental health in young adults. These findings support the importance of cognitive ER strategies as potential risk factors for psychopathology and suggest that interventions aimed at improving emotion regulation may be beneficial. The age-specific differences in the relationship between cognitive ER strategies and mental health may reflect the refinement of emotion regulation abilities across the lifespan.

Comparative efficacy of psychological interventions on immune biomarkers: A systematic review and network meta-analysis (NMA).

Psychological interventions are viable, cost-effective strategies for improving clinical and psychological impact of inflammation-related conditions. However, their efficacy on immune system function remains controversial. We performed a systematic review and frequentist random-effects network meta-analysis of randomised controlled trials (RCTs) assessing the effects of psychological interventions, against a control condition, on biomarkers of innate and adaptive immunity in adults. PubMed, Scopus, PsycInfo, and Web of Science were searched from inception up to Oct 17, 2022. Cohen's d at 95% confidence interval (CI) was calculated to assess the effect sizes of each class of intervention against active control conditions at post-treatment. The study was registered in PROSPERO (CRD42022325508). Of the 5024 articles retrieved, we included 104 RCTs reporting on 7820 participants. Analyses were based on 13 types of clinical interventions. Compared with the control conditions, cognitive therapy (d =  - 0.95, 95% CI: -1.64 to - 0.27), lifestyle (d =  - 0.51, 95% CI: -0.99 to - 0.02), and mindfulness-based (d =  - 0.38, 95% CI: -0.66 to - 0.09) interventions were associated with post-treatment reduction of proinflammatory cytokines and markers. Mindfulness-based interventions were also significantly associated with post-treatment increase in anti-inflammatory cytokines (d = 0.69, 95% CI: 0.09 to 1.30), while cognitive therapy was associated also with post-treatment increase in white blood cell count (d = 1.89, 95% CI: 0.05 to 3.74). Results on natural killer cells activity were non-significant. Grade of evidence was moderate for mindfulness and low-to-moderate for cognitive therapy and lifestyle interventions; however, substantial overall heterogeneity was detected in most of the analyses.

Psychosocial and behavioural predictors of immune response to influenza vaccination: a systematic review and meta-analysis.

High variability of influenza vaccine efficacy requires the identification of modulators of immunisation that may be targeted as adjuvants in health psychology interventions. Psychosocial and behavioural variables such as psychological stress, greater negative and lower positive affectivity, poor sleep, loneliness, and lack of social support, have been associated with abnormal immune and inflammatory responses and negative health outcomes, yet their effects in modulating vaccine efficacy are yet to be fully understood. We conducted an updated systematic review of longitudinal and experimental studies examining the effects of such variables in predicting immune response to influenza vaccine. PubMed, Medline, PsycINFO, CINAHL and Scopus were searched up to November 2022. Twenty-five studies met the inclusion criteria for qualitative synthesis and 16 provided data for meta-analysis. Low positive and high negative affect were associated with low antibodies and weak cell-mediated immunity following vaccination in qualitative synthesis. Literature on sleep disturbance, loneliness and social support was limited and yielded inconsistent results. Psychological stress was associated with poorer antibody response in meta-analysis. In conclusion, findings from this review suggest a need for further longitudinal and experimental studies on these factors to support their inclusion as target variables in vaccine adjuvant interventions.

Perfectionistic Children and Their Parents: Is There Room for an Intergenerational Transmission? A Study of a Clinical Sample of Italian Children and Their Parents.

INTRODUCTION: The relationship between maladaptive perfectionism and Internalizing (ID) and Externalizing Disorders (ED) in children needs to be better understood, along with the intergenerational transmission of these traits from parents to children. The present work aimed to share light on both these issues. METHOD: 39 children with ID, 19 with ED, and their parents were recruited*. The Multidimensional Perfectionism Scale, the Big Five Inventory, the Child and Adolescent Perfectionism Scale, and the Hierarchical Personality Inventory for Children were used. The association between parent personality and perfectionism traits and children's perfectionism dimensions was evaluated through hierarchical regression analysis. RESULTS: ID and ED groups did not differ significantly concerning perfectionism. Fathers presented higher scores than mothers in Self-Oriented Perfectionism, Other-Oriented Perfectionism, and Socially-Prescribed Perfectionism. Parents of children with ID report higher levels of Obedience in their children, while parents of children with ED reported higher levels of Creativity and Perseverance. Significant associations were found between perfectionism in parents and their children, as well as between perfectionism and the personality of children. CONCLUSION: Results suggest a transdiagnostic nature of Perfectionism and support the transgenerational transmission of the personality traits investigated.

Perseverative Cognition and Psychotic-Like Experiences in Young Adults: A Cross-Lagged Panel Model.

Psychotic-like experiences (PLEs), including persecutory ideation, bizarre experiences, and perceptual abnormalities, are considered risk factors for psychotic disorders and mental distress in the general population. The cognitive-affective mechanisms associated with PLEs remain under-investigated. We aimed to longitudinally assess the reciprocal associations between perseverative cognition (PC), an emerging transdiagnostic factor of psychopathology, and PLEs facets in young adults. Participants (n = 160) from the general population completed measures of PC and PLEs at baseline and at 2-month follow-up. A two-wave, three-variable, cross-lagged panel model was implemented controlling for well-established correlates of PC and PLEs such as depression, anxiety, and symptoms of sleep disturbance. Both PLEs and PC exhibited substantive rank-order stability (ß ranged from 0.359 to 0.657, ps < 0.001). Cross-lagged effects revealed that baseline PC was associated with bizarre experiences at 2-month follow-up (ß = 0.317; p < 0.01). This effect overcame the well-established cut-off for practical significance. In contrast, no baseline PLEs were associated with PC at follow-up. Findings suggest the presence of a monodirectional, rather than bidirectional, association between PC and bizarre experiences in young adulthood. Results should be interpreted in light of the relatively small, non-clinical, and convenient sample.

Prospective associations between grandiose narcissism and perfectionism: A longitudinal study in adolescence.

The current study investigates the longitudinal association between grandiose narcissism and multidimensional perfectionism over 2 years in adolescence. We adopted the Narcissistic Admiration and Rivalry Concept, which differentiates between two aspects of grandiose narcissism. We also considered multiple dimensions of perfectionism, including Socially Prescribed Perfectionism (SPP) and two forms of Self-Oriented Perfectionism (SOP), namely the tendencies to set high standards of performance (SOP-Striving) and to engage in overly critical self-evaluations (SOP-Critical). The study was conducted in a sample of Italian high school students (n = 331). Concurrent correlations indicated that Admiration was positively related to SOP-Striving and, to a lesser extent, to SOP-Critical and SPP. Rivalry was also positively related to the three perfectionistic dimensions, although correlations were smaller in size than those found for Admiration. Prospective associations between narcissism and perfectionism were analysed using a Random-Intercept Cross-Lagged Panel Model. Results showed that the predominant direction of effects was from narcissism to perfectionism, particularly from Admiration to SOP-Striving and SPP. Findings were discussed in terms of their implications for the understanding of the narcissism-perfectionism link.

Peripheral brain-derived neurotrophic factor (BDNF) in insomnia: A systematic review and meta-analysis.

The brain-derived neurotrophic factor (BDNF) is associated with emotional and cognitive functioning, and it is considered a transdiagnostic biomarker for mental disorders. Literature on insomnia related BDNF changes yielded contrasting results and it has never been synthetized using meta-analysis. To fill this gap, we conducted a systematic review and meta-analysis of case-control studies examining the levels of peripheric BDNF in individuals with insomnia and healthy controls using the PRISMA guidelines. PubMed, Scopus, Medline, PsycINFO and CINAHL were searched up to Nov 2022. Nine studies met the inclusion criteria and were assessed using the Newcastle-Ottawa Scale. Eight studies reported sufficient data for meta-analysis. Random-effects models showed lower BDNF in subjects with insomnia (n = 446) than in controls (n = 706) (Hedge's g = -0.86, 95% CI: -1.39 to -0.32, p = .002). Leave-one-out sensitivity analysis confirmed that the pooled effect size was robust and not driven by any single study. However, given the small sample size, the cross-sectional nature of the measurement, and the high heterogeneity of included data, the results should be cautiously interpreted. Progress in the study of BDNF in insomnia is clinically relevant to better understand the mechanisms that may explain the relationship between disturbed sleep and mental disorders.