Early-life origin of adult insomnia: does prenatal–early-life stress play a role?

Defining and distinguishing early life stress, trauma, adversity, toxic and chronic stress and allostatic load: a descriptive review

AIMS

Various concepts are used to study the impact of stress on childhood development. These concepts are often used inconsistently or interchangeably. Our main objectives were to determine how selected stress concepts (chronic stress, toxic stress, allostatic load, early life stress, childhood adversity, childhood trauma and adverse childhood experiences; ACEs) are defined, operationalized and described, and to provide a theoretical context to aid the choice for a preferred concept in public health research.

METHODS

For this descriptive review, we systematically searched for literature published before 4 August 2021, on PubMed, Embase and PsycInfo. Two independent reviewers included studies. Exclusion criteria were: no systematic review, not peer reviewed, not published in English, selected stress concepts were no predetermined variable or a substantial topic in the discussion, full text was unobtainable or study described non-human or non-childhood populations. Data extraction forms were used. Descriptives were gathered, publication fields were identified through Journal Citation Reports categories, and verbatim descriptions were ordered in text and Venn diagrams.

RESULTS

Of 264 screened studies, 124 were included. ACEs, childhood adversity and childhood trauma were used most. ACEs were the main concept used most frequently (47.6%). A total of 11 of 14 public and environmental health journals used ACEs. All concepts refer to prolonged, repeated, interpersonal stress from 0 to 18 years, that can alter physiological systems. Four concepts were stressor oriented, two concepts focused on stress response and effect and one on the state of challenged homeostasis.

CONCLUSIONS

ACEs seem most fitting for public health setting, due to their operationalizability, large set of core experiences and widespread use.

Maternal Depression and Sleep Problems in Early Childhood: A Meta-Analysis

Both prenatal and postnatal maternal depression have been associated with increased sleep problems in early childhood. However, this association is less consistent for postnatal depression, and the strength of the association remains unclear. The aim of the current study was to provide a quantitative synthesis of the literature to estimate the magnitude of the association between maternal depression and sleep problems in early childhood. Medline, PsycINFO, PsycARTICLES, Web of Science, and Scopus were searched for prospective longitudinal studies from 1970 to December 2022. Of 117 articles screened, 22 studies met the inclusion criteria. Both prenatal depression (OR = 1.82; 95% CI = 1.28-2.61) and postnatal depression (OR = 1.65; 95% CI = 1.50-1.82) were associated with increased likelihood of sleep problems in early childhood. The heterogeneity between the studies was significant and high both for prenatal (Q = 432.323; I2 = 97.456, P < .001) and postnatal depression (Q = 44.902, I2 = 65.594, P < .001), which mean that conclusions are tentative and need to be considered within the possible influence of unmeasured confounding. However, mitigating depression symptoms in mothers both during pregnancy and in the postnatal period would be an effective strategy for reducing sleep problems in children.

Exploring relationship of poor sleeping habits with prenatal stress among pregnant women in Pakistan: a cross-sectional study

OBJECTIVE

Pregnancy is a complex phenomenon accompanied by biological, physiological and psychosocial changes for a mother. It is also regarded as a stressful life event where a woman's role, identity and interpersonal relationships are restructured. The present study from Pakistan explores the association of sleep quality and poor sleeping habits with prenatal stress using Pittsburgh Sleep quality Index.

RESULTS

There were a total of 516 women (mean age = 29.82 years), with more than half reporting poor sleep quality. Ethnically, a majority (395, 76.6%) were natives of the Punjab province while rest were non-natives. A high percentage of respondents reported poor subjective sleep quality (22.1%), sleep latency (44.1%), habitual sleep efficiency (27.5%), sleep disturbance (30.1%), use of medications (7.1%) and daytime dysfunction (29.5%). According to logistic regression analysis, respondents with poor sleep quality were 2.24 (95% CI = 1.55-3.22, P < 0.001) times more likely to have high stress levels (P < 0.001).

Developmental alcohol exposure is exhausting: Sleep and the enduring consequences of alcohol exposure during development

Prenatal alcohol exposure is the leading nongenetic cause of human intellectual impairment. The long-term impacts of prenatal alcohol exposure on health and well-being are diverse, including neuropathology leading to behavioral, cognitive, and emotional impairments. Additionally negative effects also occur on the physiological level, such as the endocrine, cardiovascular, and immune systems. Among these diverse impacts is sleep disruption. In this review, we describe how prenatal alcohol exposure affects sleep, and potential mechanisms of those effects. Furthermore, we outline the evidence that sleep disruption across the lifespan may be a mediator of some cognitive and behavioral impacts of developmental alcohol exposure, and thus may represent a promising target for treatment.

A Longitudinal Study of Stress During Pregnancy, Children's Sleep and Polygenic Risk for Poor Sleep in the General Pediatric Population

Early life stress is robustly associated with poor sleep across life. Preliminary studies suggest that these associations may begin already in utero. Here, we study the longitudinal associations of prenatal psychosocial stress with sleep across childhood, and assess whether prenatal stress interacts with genetic liability for poor sleep.The study is embedded in the Generation R population-based birth cohort. Caregivers reported on prenatal psychosocial stress (life events, contextual, parental or interpersonal stressors) and on children's sleep at ages 2 months, 1.5, 2, 3 and 6 years. The study sample consisted of 4,930 children; polygenic risk scores for sleep traits were available in 2,063.Prenatal stress was consistently associated with more sleep problems across assessments. Effect sizes ranged from small (B = 0.21, 95%CI: 0.14;0.27) at 2 months to medium (B = 0.45, 95%CI: 0.38;0.53) at 2 years. Prenatal stress was moreover associated with shorter sleep duration at 2 months (Bhrs = -0.22, 95%CI: -0.32;-0.12) and at 2 years (Bhrs = -0.04, 95%CI -0.07; -0.001), but not at 3 years (Bhrs = 0.02, 95%CI: -0.02;0.06). Prenatal negative life events interacted with polygenic risk for insomnia to exacerbate sleep problems at 6 years (Binteraction = 0.07, 95%CI: 0.02;0.13).Psychosocial stress during pregnancy has negative associations with children's sleep that persist across childhood, and are exacerbated by genetic liability for insomnia. Associations with sleep duration were more pronounced in infancy and seem to attenuate with age. These findings highlight the role of the prenatal environment for developing sleep regulation, and could inform early intervention programs targeting sleep in children from high-risk pregnancies.

Potential genetic and epigenetic mechanisms in insomnia: A systematic review

Insomnia is a stress-related sleep disorder conceptualised within a diathesis-stress framework, which it is thought to result from predisposing factors interacting with precipitating stressful events that trigger the development of insomnia. Among predisposing factors genetics and epigenetics may play a role. A systematic review of the current evidence for the genetic and epigenetic basis of insomnia was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) system. A total of 24 studies were collected for twins and family heritability, 55 for genome-wide association studies, 26 about candidate genes for insomnia, and eight for epigenetics. Data showed that insomnia is a complex polygenic stress-related disorder, and it is likely to be caused by a synergy of genetic and environmental factors, with stress-related sleep reactivity being the important trait. Even if few studies have been conducted to date on insomnia, epigenetics may be the framework to understand long-lasting consequences of the interaction between genetic and environmental factors and effects of stress on the brain in insomnia. Interestingly, polygenic risk for insomnia has been causally linked to different mental and medical disorders. Probably, by treating insomnia it would be possible to intervene on the effect of stress on the brain and prevent some medical and mental conditions.

Social disparities in sleep health of African populations: A systematic review and meta-analysis of observational studies

OBJECTIVES

To document the relationship between socioeconomic status (SES) and sleep health in African populations.

METHODS

Observational cross-sectional or cohort studies examining the association between SES indicators and sleep outcomes in participants from African countries were included. The search was performed in the MEDLINE, Embase, and Web of Science Core Collection electronic databases in June 2021. Selection, confounding, attrition/exclusion, detection, and selective reporting bias were assessed using the OHAT Risk of Bias Tool. Random effects meta-analysis was used for summarizing the effect estimates.

RESULTS

Forty-three reports were selected, having sampled 153,372 Africans from 26 countries. Education was the most frequent SES indicator and composite measures of sleep quality or disturbances was the most common sleep outcome. Low educational attainment was significantly associated with lower odds of short sleep (odds ratio [OR]=0.65, 95% confidence intervals [0.50, 0.84], p = .001) and higher odds of insomnia (OR=1.53, [1.18, 1.99], p = .001) or poor sleep quality (OR=1.60, [1.17, 2.18], p = .003). Low levels of income/assets were related to higher odds of insomnia (OR=1.38, [1.02, 1.86], p = .04) and low occupational/employment status was linked to lower odds of short sleep duration (OR=0.49, [0.30, 0.79], p = .004).

CONCLUSIONS

Socioeconomic disadvantage was a significant predictor of insomnia and poor sleep quality, while it was associated with longer sleep duration. Significant heterogeneity in terms of exposure and outcomes, scarcity of longitudinal designs, lack of objective outcome measurement, and low representation of rural samples and participants from low-income countries limit the quality of evidence.

From childhood adversity to latent stress vulnerability in adulthood: the mediating roles of sleep disturbances and HPA axis dysfunction

Childhood adversity is a prominent predisposing risk factor for latent stress vulnerability, expressed as an elevated likelihood of developing stress-related psychopathology upon subsequent exposure to trauma in adulthood. Sleep disturbances have emerged as one of the most pronounced maladaptive behavioral outcomes of childhood adversity and are also a highly prevalent core feature of stress-related psychopathology, including post-traumatic stress disorder (PTSD). After reviewing the extensive literature supporting these claims, the current review addresses the notion that childhood adversity-induced sleep disturbances may play a causal role in elevating individuals' stress vulnerability in adulthood. Corroborating this, sleep disturbances that predate adult trauma exposure have been associated with an increased likelihood of developing stress-related psychopathology post-exposure. Furthermore, novel empirical evidence suggests that sleep disturbances, including irregularity of the sleep-wake cycle, mediate the link between childhood adversity and stress vulnerability in adulthood. We also discuss cognitive and behavioral mechanisms through which such a cascade may evolve, highlighting the putative role of impaired memory consolidation and fear extinction. Next, we present evidence to support the contribution of the hypothalamic-pituitary-adrenal (HPA) axis to these associations, stemming from its critical role in stress and sleep regulatory pathways. Childhood adversity may yield bi-directional effects within the HPA stress and sleep axes in which sleep disturbances and HPA axis dysfunction reinforce each other, leading to elevated stress vulnerability. To conclude, we postulate a conceptual path model from childhood adversity to latent stress vulnerability in adulthood and discuss the potential clinical implications of these notions, while highlighting directions for future research.

Understanding neuron-glia crosstalk and biological clocks in insomnia

According to the World Health Organization, about one-third of the population experiences insomnia symptoms, and about 10-15% suffer from chronic insomnia, the most common sleep disorder. Sleeping difficulties associated with insomnia are often linked to chronic sleep deprivation, which has a negative health impact partly due to disruption in the internal synchronisation of biological clocks. These are regulated by clock genes and modulate most biological processes. Most studies addressing circadian rhythm regulation have focused on the role of neurons, yet glial cells also impact circadian rhythms and sleep regulation. Chronic insomnia and sleep loss have been associated with glial cell activation, exacerbated neuroinflammation, oxidative stress, altered neuronal metabolism and synaptic plasticity, accelerated age-related processes and decreased lifespan. It is, therefore, essential to highlight the importance of glia-neuron interplay on sleep/circadian regulation and overall healthy brain function. Hence, in this review, we aim to address the main neurobiological mechanisms involved in neuron-glia crosstalk, with an emphasis on microglia and astrocytes, in both healthy sleep, chronic sleep deprivation and chronic insomnia.

The Nucleus Accumbens CRH-CRHR1 System Mediates Early-Life Stress-Induced Sleep Disturbance and Dendritic Atrophy in the Adult Mouse

Adverse experiences in early life have long-lasting negative impacts on behavior and the brain in adulthood, one of which is sleep disturbance. As the corticotropin-releasing hormone (CRH)-corticotropin-releasing hormone receptor 1 (CRHR1) system and nucleus accumbens (NAc) play important roles in both stress responses and sleep-wake regulation, in this study we investigated whether the NAc CRH-CRHR1 system mediates early-life stress-induced abnormalities in sleep-wake behavior in adult mice. Using the limited nesting and bedding material paradigm from postnatal days 2 to 9, we found that early-life stress disrupted sleep-wake behaviors during adulthood, including increased wakefulness and decreased non-rapid eye movement (NREM) sleep time during the dark period and increased rapid eye movement (REM) sleep time during the light period. The stress-induced sleep disturbances were accompanied by dendritic atrophy in the NAc and both were largely reversed by daily systemic administration of the CRHR1 antagonist antalarmin during stress exposure. Importantly, Crh overexpression in the NAc reproduced the effects of early-life stress on sleep-wake behavior and NAc morphology, whereas NAc Crhr1 knockdown reversed these effects (including increased wakefulness and reduced NREM sleep in the dark period and NAc dendritic atrophy). Together, our findings demonstrate the negative influence of early-life stress on sleep architecture and the structural plasticity of the NAc, and highlight the critical role of the NAc CRH-CRHR1 system in modulating these negative outcomes evoked by early-life stress.

Encore: Behavioural animal models of stress, depression and mood disorders

Animal studies over the past two decades have led to extensive advances in our understanding of pathogenesis of depressive and mood disorders. Among these, rodent behavioural models proved to be of highest informative value. Here, we present a comprehensive overview of the most popular behavioural models with respect to physiological, circuit, and molecular biological correlates. Behavioural stress paradigms and behavioural tests are assessed in terms of outcomes, strengths, weaknesses, and translational value, especially in the domain of pharmacological studies.

The Moderating Role of Stress Response on the Relationship Between Subjective Sleep Quality and Suicide Ideation in Adolescence

OBJECTIVE

Problems sleeping and stress are known to contribute to the development of suicide ideation. However, it is unclear how these risk factors interact longitudinally. The purpose of this study was to determine the impact of problems sleeping on the development of suicide ideation in adolescence one year later and how the relationship changes with the addition of stress as a moderator.

METHOD

Data were collected from 153 adolescents (M age = 12.8, SD = 1.6) over three years as part of a larger study. Participants completed the MINI-Kid and Youth Self-Report, which were used to assess for suicidality. The Stress scale of the YSR was used to measure stress. Participants also completed the Adolescent Sleep Wake Scale, which was used to assess their perceptions of their sleep quality.

RESULTS

Logistic moderation analyses demonstrated a significant interaction between ASWS and YSR Stress in the prediction of suicide ideation one year later, Wald χ²(1)=4.57, OR = 0.68, p < 0.05. Results demonstrated higher odds of endorsing SI as stress increased when sleep quality was poor (OR = 21.51) compared to when sleep quality was high (OR = 4.03), suggesting that adequate sleep may act as a protective factor against suicide ideation.

CONCLUSIONS

The results are indicative of long-term consequences of sleep on adolescent mental health, particularly when faced with high levels of stress. These results may have significant clinical implications for suicide prevention efforts as this relationship may help identify at-risk adolescents prior to the initial experience of suicide ideation.

Effects of stress on endophenotypes of suicide across species: A role for ketamine in risk mitigation

Suicide is a leading cause of death and morbidity worldwide, yet few interventions are available to mitigate its risk. Barriers to effective treatments involve a limited understanding of factors that predict the onset of suicidal thoughts and behaviors. In the context of suicide risk, stress is a precipitating factor that is largely overlooked in the literature. Indeed, the pathophysiology of stress and suicide are heavily interconnected, underscoring the need to target the stress system in suicide prevention. In this review, we integrate findings from the preclinical and clinical literature that links stress and suicide. We focus specifically on the effects of stress on underlying biological functions and processes associated with suicide, allowing for the review of research using animal models. Owing to the rapid anti-suicidal effects of (R,S)-ketamine, we discuss its ability to modulate various stress-related endophenotypes of suicide, as well as its potential role in preventing suicide in those with a history of chronic life stress (e.g., early life adversity). We highlight future research directions that could advance our understanding of stress-related effects on suicide risk, advocating a dimensional, endophenotype approach to suicide research.

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Suicide and chronic stress pathophysiology are interconnected.

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Chronic stress has profound impacts on several endophenotypes of suicide.

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Animal and human research points to stress as a precipitating factor in suicide.

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Ketamine modulates specific biological processes associated with stress and suicide.

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Suicide research into endophenotypes can help inform risk-mitigation strategies.

Autonomic behavioral impairment induced by simazine exposure during early life of male mouse is mediated by Lmx1a/Wnt1 pathway

Simazine is a widely used herbicide and known as an environmental estrogen. Multiple studies have proved simazine can induced the degeneration of dopaminergic neuron resulting in a degenerative disease-like syndrome. Herein, we explored the neurotoxicity of simazine on the dopaminergic nervous system of embryos and weaned offspring during the maternal gestation period or the maternal gestation and lactation periods. We found that simazine disturbed the crucial components expression involved in Lmx1a/Wnt1 pathway of dopaminergic neuron in embryonic and weaned offspring. Furthermore, morphological and behavioral tests performed on weaned male offspring treated by simazine suggested that the grip strength, autonomic exploring, and the space sense ability were weakened, as well as the pathological damage of dopaminergic neuron was clearly observed. But, the same neurotoxicity of simazine is less significantly observed in female offspring. Our findings will provide reliable reference for the determination of environmental limits and new insight into the pathogenesis of nonfamilial neurodegenerative diseases related to environmental risk factors.

Intergenerational Effects of Discrimination on Black American Children's Sleep Health

Greater exposure to racial/ethnic discrimination among pregnant Black American women is associated with elevated prenatal depressive symptomatology, poorer prenatal sleep quality, and poorer child health outcomes. Given the transdiagnostic importance of early childhood sleep health, we examined associations between pregnant women's lifetime exposure to racial/ethnic discrimination and their two-year-old children's sleep health. We also examined women's gendered racial stress as a predictor variable. In exploratory analyses, we examined prenatal sleep quality and prenatal depressive symptoms as potential mediators of the prior associations. We utilized data from a sample of Black American women and children (n = 205). Women self-reported their lifetime experiences of discrimination during early pregnancy, their sleep quality and depressive symptoms during mid-pregnancy, and their children's sleep health at age two. Hierarchical linear multiple regression models were fit to examine direct associations between women's experiences of discrimination and children's sleep health. We tested our mediation hypotheses using a parallel mediator model. Higher levels of gendered racial stress, but not racial/ethnic discrimination, were directly associated with poorer sleep health in children. Higher levels of racial/ethnic discrimination were indirectly associated with poorer sleep health in children, via women's prenatal depressive symptomatology, but not prenatal sleep quality. Clinical efforts to mitigate the effects of discrimination on Black American women may benefit women's prenatal mental health and their children's sleep health.

Insomnia symptoms are associated with impaired resilience in bipolar disorder: Potential links with early life stressors may affect mood features and suicidal risk

AIM

The study aimed to investigate resilience and its association with early exposure to stressful events on the clinical manifestations of bipolar disorders (BDs), such as severity of mood symptoms, suicidal ideation and behaviors focusing on the possible role of insomnia symptoms.

METHOD

A sample of 188 adult participants with BD of type I or II were assessed during depressed phase using the Structural Clinical Interview for DSM-5 (SCID-5), the Beck Depression Inventory-II (BDI-II), the Young Mania Rating Scale (YMRS), the Early Trauma Inventory Self Report-Short Form (ETISR-SF), Resilience Scale for Adults (RSA), the Insomnia Severity Index (ISI) and the Scale for Suicide Ideation (SSI). Participants with or without clinically significant insomnia were compared and we carried out correlations, regression and mediation analyses.

RESULTS

Participants with insomnia showed a greater severity of depressive symptoms as well as of suicidal risk, early life stressors and lower level of resilience. Insomnia symptoms mediated the association between early life stress and low resilience, between low resilience in planning future and depressive symptoms (Z = 2.17, p = 0.029) and low resilience and suicidal risk (Z = 3.05, p = 0.0002) CONCLUSION: Insomnia may be related to the severity of BDs, to higher early life stressors and lower level of resilience. Assessing and targeting insomnia symptoms may potentially promote resilience in BDs in response to early life stressful events. These results should be interpreted in light of several limitations including the cross-sectional design affecting causal interpretations.

Prenatal psychosocial stress and children's sleep problems: Evidence from the ELSPAC-CZ study

Prenatal exposure to maternal stress may increase the risk of developing sleep problems in childhood. This study examined the association between prenatal stressful life events (PSLE) and children's sleep problems, taking into consideration their trajectory over time. Data were obtained from the Czech portion of the European Longitudinal Cohort Study of Pregnancy and Childhood (ELSPAC-CZ; N = 4,371 children). Mothers reported PSLE using an inventory of 42 life events and child sleep problems at five time-points (child age of 1.5, 3, 5, 7, and 11 years). The association was tested by a Poisson latent growth model, controlling for maternal and family demographics, birth characteristics, maternal depression, and alcohol use in pregnancy. The average rate of sleep problems was 2.06 (p < 0.001) at the age of 1.5 years and the rate of sleep problems decreased in a linear fashion over time (estimate = -0.118; p < 0.001). A higher number of PSLE was associated with a higher rate of sleep problems at the age of 1.5 years (incidence rate ratio [IRR] per interquartile range = 1.08, 95% confidence interval [CI] 1.05-1.12, p < 0.001) and with a reduced rate of decrease in sleep problems between the ages of 1.5 and 11 years (p < 0.001). Thus, PSLE were associated with chronicity of sleep problems in addition to their amount during early childhood. Prenatal exposure to stress may predispose individuals to the development of sleep problems in later life.

Infant diurnal cortisol predicts sleep

The sleep-wake system is immature at birth and develops in parallel with the hypothalamic-pituitary-adrenal axis, a biological stress system of which the end product is cortisol. Perturbations in one system during infancy can maladaptively influence the maturation of the other system, leading to lasting sleep and cortisol system dysregulation and heightening the risk of enduring health problems. To better understand the early interplay between these systems, we examined whether actigraphy-derived measures of night-time sleep duration and onset were associated with cumulative exposure to cortisol, indexed by hair cortisol concentration, in 12-month-old children. Overall, early sleep onset predicted lower hair cortisol above and beyond sleep duration, family income and chaos experienced at home. Furthermore, both sleep and cortisol levels vary day to day, and temporal dependencies between daily sleep and cortisol regulation are not well understood. Thus, we assessed how the sleep characteristics on a particular evening related to salivary cortisol levels the following day and how daytime and evening cortisol related to the sleep characteristics on the same night. Lower total exposure to cortisol on a particular day was related to longer night-time sleep duration the same night, but not sleep onset. Lower salivary cortisol levels on a given evening related to earlier sleep onset the same night, but not to night-time sleep duration. Sleep duration and onset on a given night were unrelated to total cortisol exposure the following day. Findings suggest that in early development, the day-to-day relation between sleep and cortisol is not bidirectional, but more driven by diurnal cortisol.

Associations of adverse childhood experiences with adolescent total sleep time, social jetlag, and insomnia symptoms

STUDY OBJECTIVE

Adverse childhood experiences (ACEs) are associated with sleep problems in adulthood, but less research has focused on ACEs and sleep during adolescence. The goal of the present study was to explore associations between ACEs reported at ages 5 and 9 years, and sleep (ie, total sleep time (TST), social jetlag, and insomnia symptoms) at age 15.

METHODS

Participants comprised 817 families from the Fragile Families and Child Wellbeing Study, a nationally representative sample of children born to unwed parents. Number of ACEs was constructed from primary-caregiver reports at ages 5 and 9, and sleep measures (ie, TST, social jetlag, and insomnia symptoms) were derived from adolescent-reported sleep behaviors at age 15.

RESULTS

Adjusting for sex and race/ethnicity, ACEs at age 9 were associated with longer weekend TST (B = 0.16, 95% CI = 0.04, 0.28), more social jetlag (B = 0.17, 95% CI = 0.07, 0.27), and higher odds of trouble falling asleep ≥3 times per week (Odds Ratio = 1.24, 95% CI = 1.01, 1.53). In females only, ACEs were associated with greater school night TST (B = 0.12, 95% CI = 0.01, 0.23). Results were similar after further adjustment for symptoms of anxiety and depression. Associations among ACEs, social jetlag, and insomnia symptoms appeared strongest among Non-Hispanic Black adolescents.

CONCLUSION

ACEs appear to be related to multiple aspects of sleep in adolescence. Additional research is needed to confirm these associations and examine the extent to which sleep disturbances associated with ACEs account for later health outcomes.

The Experiences and Determinants of Sleep Problems of Immigrant and Canadian-Born Older Adults-Analysis of Canadian Longitudinal Study on Aging Baseline Data

BACKGROUND

Although prevalent, limited knowledge is available on the experience of sleep problems (i.e., disturbance in sleep latency and in sleep maintenance) and their determinants in immigrant older adults.

PURPOSE

To compare immigrant and Canadian-born older adults' experiences of: 1) sleep problems, 2) determinants of sleep problems, categorized into precipitating and perpetuating factors, and 3) determinants most significantly contributing to each sleep problem.

METHODS

Baseline data obtained by the comprehensive cohort of the Canadian Longitudinal Study on Aging were analyzed. Participants 55+ years of age and with complete data on their country of birth comprised the sample, with 18,245 Canadian-born and 4,257 immigrant older adults. Single or multiple items were used to assess the precipitating (chronic condition, sleep disorders, pain, depressive symptoms, psychological distress, education, marital and socio-economic status) and perpetuating (smoking, alcohol consumption, physical activity) factors. Chi-square test and independent sample t-test were used in the comparison and multiple regression was applied to determine the most significant determinant of each sleep problem in each group of older adults.

RESULTS

Despite differences in a few determinants of sleep problems, the set of factors contributing to disturbance in sleep latency and maintenance was comparable for Canadian-born and immigrant older adults, and included: having a sleep disorder and high level of depressive symptoms and psychological distress.

CONCLUSION

The findings highlight the importance of public health campaigns to increase older adults' awareness of sleep problems, the factors that may contribute to disturbance in sleep, and strategies to prevent and/or manage sleep problems.

Sleep Well and Recover Faster with Less Pain-A Narrative Review on Sleep in the Perioperative Period

Sleep disturbance, pain, and having a surgical procedure of some kind are all very likely to occur during the average lifespan. Postoperative pain continues to be a prevalent problem and growing evidence supports the association between pain and sleep disturbances. The bidirectional nature of sleep and pain is widely acknowledged. A decline in sleep quality adds a risk for the onset of pain and also exacerbates existing pain. The risk factors for developing insomnia and experiencing severe pain after surgery are quite similar. The main aim of this narrative review is to discuss why it is important to be aware of sleep disturbances both before and after surgery, to know how sleep disturbances should be assessed and monitored, and to understand how better sleep can be supported by both pharmacological and non-pharmacological interventions.

The association of childhood trauma with sleep disturbances and risk of suicide in US veterans

BACKGROUND

Sleep dysregulation is prevalent among veterans and is associated with increased risk of suicidal ideation and behaviors. A confluence of risk factors have been identified to date that contribute to increase risk for suicidal behavior. How these risk factors including childhood trauma, comorbid psychopathology, impulsivity, and hostility together with sleep disturbance contribute to suicide risk remains an open question. These factors have never been examined simultaneously in a unified mediation model, as investigated in the present study, to determine their relative contribution to suicide risk.

METHODS

Veterans (N = 105) were recruited across 3-groups, including Major Depressive Disorder (MDD) with/without a history of a suicide attempt (n = 35 and n = 37, respectively), and non-psychiatric controls, who had no history of mental illness or suicidal behavior (n = 33). The participants were assessed using validated self-report assessments with in-depth phenotyping for relevant risk factors associated with suicidal behavior including childhood adversity, depression severity, impulsivity, hostility, and sleep quality. These factors were included in mediation models using path analysis.

RESULTS

Across all subjects including those with MDD and non-psychiatric controls, mediation analysis showed that higher levels of childhood trauma had an indirect effect on poor sleep quality (p = 0.001). This effect was orthogonal, being independently mediated by both MDD psychopathology (p = 0.003), and higher traits of impulsivity (p = 0.001) and hostility (p = 0.015). Amongst MDD veterans, childhood trauma was directly associated with increased suicide risk (p = 0.034), irrespective of their severity of depression, or their degree of hostility and impulsivity.

LIMITATIONS

include use of self-report data, and the inability to establish causal inferences with cross-sectional design.

CONCLUSION

Childhood adversity as a significant pre-deployment risk factor for disturbed sleep and elevated suicide risk, potentially important for incorporation in clinical practice for suicide.

Prenatal and postnatal exposure to Tangshan earthquake and CRHR1 gene polymorphism influence risk of sleep disturbance in adulthood

To determine the effect of earthquake on sleep quality of adults who had experienced Tangshan Earthquake either as infants or fetuses and also investigate whether CRHR1 polymorphism influenced sleep quality in subjects exposed to seismic stress.Totally 556 subjects were enrolled in the current study and were divided into 3 groups, those who had experienced Tangshan Earthquake as infants (group I) or fetuses (group II), and those who had not experienced Tangshan Earthquake (group III). Sleep was evaluated using the Pittsburgh Sleep Quality Index (PQSI). Three single nucleotide polymorphisms of the CRHR1 gene were analyzed.Fifty two (9.4%) subjects had sleep disturbance, including 17 (9.9%) subjects in group I, 24 (13.4%) subjects in group II, and 11 (5.3%) subjects in group III (χ2 = 7.373, P = .025). Moreover, subjects with CRHR1 genotype T/T had a significantly lower rate of sleep disturbance (7.8%) than subjects with genotype C/T and C/C (14.7%; χ2 = 4.845, P  = .028). Furthermore, subjects with rs7209436 genotype C had an approximately 2-fold increase in the risk of sleep disturbance versus those who were not genotype C (OR = 1.978, 95% CI (1.045, 3.744).Prenatal and postnatal exposure to seismic stress significantly increases subsequent risk of sleep disturbance in adulthood.

Association among early life stress, mood features, hopelessness and suicidal risk in bipolar disorder: The potential contribution of insomnia symptoms

AIM

The study aimed to investigate the potential pathways mediating early exposure to stressful events and the clinical manifestations of bipolar disorder (BD), such as severity of mood symptoms, hopelessness and suicidal ideation, focusing on the potential role of insomnia symptoms.

METHOD

A sample of 162 adult participants with BD I or II were assessed during depressed phase using the Structural Clinical Interview for DSM-5 (SCID-5), the Beck Depression Inventory-II (BDI-II), the Young Mania Rating Scale (YMRS), the Early Trauma Inventory Self Report-Short Form (ETISR-SF), the Beck Hopelessness Scale (BHS), the Insomnia Severity Index (ISI) and the Scale for Suicide Ideation (SSI). Participants with or without clinically significant insomnia were compared and we carried out correlations, regression and mediation analyses.

RESULTS

Participants with insomnia showed a greater severity of depressive symptoms,of suicidal risk, of the cognitive component of hopelessness and of early life stressors. Insomnia symptoms mediated the association among early life stress and depressive symptoms (Z = 2.72, p = 0.0006), the cognitive component of hopelessness (Z = 3.02, p = 0.0001) and suicidal ideation and plans (Z = 2.07 p = 0.0006).

CONCLUSION

Insomnia may mediate the relationship between early life stress and clinical manifestations of BD. Assessing the evolution of insomnia symptoms could offer an approach to characterize BD and to formulate treatment strategies. In particular targeting insomnia symptoms might potentially modify the clinical features of BD in response to early life stressful events.

Genetic versus stress and mood determinants of sleep in the Amish

Sleep is essential to the human brain and is regulated by genetics with many features conserved across species. Sleep is also influenced by health and environmental factors; identifying replicable genetic variants contributing to sleep may require accounting for these factors. We examined how stress and mood disorder contribute to sleep and impact its heritability. Our sample included 326 Amish/Mennonite individuals with a lifestyle with limited technological interferences with sleep. Sleep measures included Pittsburgh Sleep Quality Index (PSQI), bedtime, wake time, and time to sleep onset. Current stress level, cumulative life stressors, and mood disorder were also evaluated. We estimated the heritability of sleep features and examined the impact of current stress, lifetime stress, mood diagnosis on sleep quality. The results showed current stress, lifetime stress, and mood disorder were independently associated with PSQI score (p < .05). Heritability of PSQI was low (0-0.23) before and after accounting for stress and mood. Bedtime, wake time, and minutes to sleep time did show significant heritability at 0.44, 0.42, and 0.29. However, after adjusting for shared environment, only heritability of wake time remained significant. Sleep is affected by environmental stress and mental health factors even in a society with limited technological interference with sleep. Wake time may be a more biological marker of sleep as compared to the evening measures which are more influenced by other household members. Accounting for nongenetic and partially genetic determinants of sleep particularly stress and mood disorder is likely important for improving the precision of genetic studies of sleep.

Maternal stress during pregnancy alters fetal cortico-cerebellar connectivity in utero and increases child sleep problems after birth

Child sleep disorders are increasingly prevalent and understanding early predictors of sleep problems, starting in utero, may meaningfully guide future prevention efforts. Here, we investigated whether prenatal exposure to maternal psychological stress is associated with increased sleep problems in toddlers. We also examined whether fetal brain connectivity has direct or indirect influence on this putative association. Pregnant women underwent fetal resting-state functional connectivity MRI and completed questionnaires on stress, worry, and negative affect. At 3-year follow-up, 64 mothers reported on child sleep problems, and in the subset that have reached 5-year follow-up, actigraphy data (N = 25) has also been obtained. We observe that higher maternal prenatal stress is associated with increased toddler sleep concerns, with actigraphy sleep metrics, and with decreased fetal cerebellar-insular connectivity. Specific mediating effects were not identified for the fetal brain regions examined. The search for underlying mechanisms of the link between maternal prenatal stress and child sleep problems should be continued and extended to other brain areas.

Brain mechanisms of insomnia: new perspectives on causes and consequences

While insomnia is the second most common mental disorder, progress in our understanding of underlying neurobiological mechanisms has been limited. The present review addresses the definition and prevalence of insomnia and explores its subjective and objective characteristics across the 24-hour day. Subsequently, the review extensively addresses how the vulnerability to develop insomnia is affected by genetic variants, early life stress, major life events, and brain structure and function. Further supported by the clear mental health risks conveyed by insomnia, the integrated findings suggest that the vulnerability to develop insomnia could rather be found in brain circuits regulating emotion and arousal than in circuits involved in circadian and homeostatic sleep regulation. Finally, a testable model is presented. The model proposes that in people with a vulnerability to develop insomnia, the locus coeruleus is more sensitive to-or receives more input from-the salience network and related circuits, even during rapid eye movement sleep, when it should normally be sound asleep. This vulnerability may ignite a downward spiral of insufficient overnight adaptation to distress, resulting in accumulating hyperarousal, which, in turn, impedes restful sleep and moreover increases the risk of other mental health adversity. Sensitized brain circuits are likely to be subjectively experienced as "sleeping with one eye open". The proposed model opens up the possibility for novel intervention studies and animal studies, thus accelerating the ignition of a neuroscience of insomnia, which is direly needed for better treatment.

Effects of sleep modulation during pregnancy in the mother and offspring: Evidences from preclinical research

Disturbed sleep during gestation may lead to adverse outcomes for both mother and child. Animal research plays an important role in providing insights into this research field by enabling ethical and methodological requirements that are not possible in humans. Here, we present an overview and discuss the main research findings related to the effects of prenatal sleep deprivation in animal models. Using systematic review approaches, we retrieved 42 articles dealing with some type of sleep alteration. The most frequent research topics in this context were maternal sleep deprivation, maternal behaviour, offspring behaviour, development of sleep-wake cycles in the offspring, hippocampal neurodevelopment, pregnancy viability, renal physiology, hypertension and metabolism. This overview indicates that the number of basic studies in this field is growing, and provides biological plausibility to suggest that sleep disturbances might be detrimental to both mother and offspring by promoting increased risk at the behavioural, hormonal, electrophysiological, metabolic and epigenetic levels. More studies on the effects of maternal sleep deprivation are needed, in light of their major translational perspective.

Early-life stress alters sleep structure and the excitatory-inhibitory balance in the nucleus accumbens in aged mice

Background:

Exposure to adverse experiences in early life may profoundly reshape the neurodevelopmental trajectories of the brain and lead to long-lasting behavioral and neural alterations. One deleterious effect of early-life stress that manifests in later life is sleep disturbance, but this has not been examined in aged mice and the underlying neural mechanisms remain unknown. Considering the important role of the nucleus accumbens (NAc) in the sleep-wake regulation, this study aimed to assess the effects of early-life stress on the sleep behaviors in aged mice and the potential involvement of the NAc in stress-induced sleep abnormalities.

Methods:

Twenty aged male C57BL/6 mice (>16 months, n = 10 per group) were used in this study. During post-natal days 2 to 9, dams were provided with either sufficient (control) or a limited nesting and bedding materials (stressed). When the mice were 16 to 17 months old, their sleep-wake behaviors were recorded over 24 h using electroencephalogram and electromyelogram. The amount of each sleep-wake stage, mean duration, and stage transition was analyzed. Then, five animals were randomly chosen from each group and were used to measure the expression levels of vesicular glutamate transporter-1 (VGluT1) and vesicular transporters of γ-aminobutyric acid (VGAT) in the NAc using immunohistochemistry. Group comparisons were carried out using Student t test or analysis of variances when appropriate.

Results:

Compared with the control mice, the early-life stressed aged mice spent less time awake over 24 h (697.97 ± 77.47 min vs. 631.33 ± 34.73 min, t₁₇ = 2.376, P = 0.030), accordingly, non-rapid eye movement sleep time was increased (667.37 ± 62.07 min vs. 723.54 ± 39.21 min, t₁₇ = 2.326, P = 0.033) and mean duration of rapid eye movement sleep was prolonged (73.00 ± 8.98 min vs. 89.39 ± 12.69 min, t₁₇ = 3.277, P = 0.004). Meanwhile, we observed decreased VGluT1/VGAT ratios in the NAc in the stressed group (F_{(1, 16)} = 81.04, P < 0.001).

Conclusion:

Early adverse experiences disrupt sleep behaviors in aged mice, which might be associated with the excitatory-inhibitory imbalance in the NAc.

Neuropsychological assessment and cortisol levels in biofluids from early Alzheimer's disease patients

Cortisol dysregulation is proposed as a factor in the development of Alzheimer's disease (AD). AD patients can show high cortisol levels in prodromal phases of AD, early enough that neuropsychological alterations exist but activities of daily living remain unimpaired. Nevertheless, it is unknown if biofluid cortisol levels can have some AD predictive power together with neuropsychological assessment in prodromal stages in comparison with other cognitive disorders. In this work, an analytical method based on ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) was applied to determine the cortisol levels in different biofluids (urine, plasma, saliva, cerebrospinal fluid). Early AD patients and non-AD patients recruited at out-patient neurological unit were classified from the standard cerebrospinal fluid biomarkers levels (β-amyloid, tau, phosphorylated tau), and studied with an extensive neuropsychological assessment including global, neuropsychological, functional and affective scales. We used a logistic regression model to discriminate between the AD and non-AD groups. Higher plasma cortisol levels were found in the AD group than in the non-AD group (p < 0.001). Regarding neuropsychological evaluation, delayed memory was used as representative of the neuropsychological status, and lower scores were obtained in the AD group (p < 0.001). The prediction model, including plasma cortisol levels and delayed memory scores, achieved an AUC of 0.93, as well as a sensitivity of 97% and a specificity of 69.4%. In conclusion, plasma cortisol levels and delayed memory scores were specifically impaired in early AD, allowing the development of a new diagnostic model which could be employed as a very satisfactory screening system.

Developmental pathways towards mood disorders in adult life: Is there a role for sleep disturbances?

INTRODUCTION

Mood disorders are among the most prevalent and serious mental disorders and rank high among to the leading global burdens of disease. The developmental psychopathology framework can offer a life course perspective on them thus providing a basis for early prevention and intervention. Sleep disturbances, are considered risk factors for mood disorders across childhood, adolescence and adulthood. Assuming that sleep disturbances may play a pivotal role in the pathogenesis of mood disorders from a life course point of view, we reviewed the data on developmental pathways towards mood disorders in adult life in relation to sleep disturbances.

METHOD

From February 2017, a systematic search was conducted in PubMed, PsycINFO and Embase electronic databases for literature on developmental pathways to mood disorders in adult life in relation to sleep disturbances and to 1) pre-natal stress, 2) early brain developmental processes, and 3) temperaments, character and attachment style.

RESULTS

Eleven, 54 and 15 articles were respectively selected.

CONCLUSIONS

Experimental and clinical studies revealed that exposure to prenatal/early life stress results in sleep disturbances such as poor sleep and altered circadian regulation phases and may predict or even precipitate mood disorders in adulthood. Chronic sleep disruption may interfere with neuronal plasticity, connectivity and the developing brain thus contributing to the development of mood disorders. In addition sleep and circadian dysregulations have been shown to be related to those temperaments, character and attachment styles which are considered precursors of mood disorders. Sleep and circadian behaviours may serve as early targets regarding mood disorders.

Sleep quality and perceived health in college undergraduates with adverse childhood experiences

BACKGROUND

Research demonstrates that poor sleep quality is a predictor of chronic mental and physical health problems. The link between adverse childhood experiences (ACEs) and poor health outcomes is also well established; however, few studies have examined the relationships between ACEs, sleep quality, and physical and mental health.

METHODS

The current study used structural equation modeling to assess the direct and indirect relationships between ACEs, sleep quality, symptoms of depression and anxiety, and general health perception in a sample of college undergraduates (N = 399), a group of individuals whose age is notable for only recently transitioning out of childhood.

RESULTS

Indirect (ie, mediation) effects indicated with 95% confidence that sleep quality mediated the relationship between ACEs and general health perception, depressive symptoms, and symptoms of anxiety. Sleep quality did not account for the entire relationship between ACE score and these health outcomes, indicating partial mediation. When reversing the mediator and outcome variables, depression and anxiety fully mediated the relationship between ACE score and sleep quality.

CONCLUSION

The results of this study suggest that sleep quality may be an important intermediary mechanism by which ACEs might contribute to poor health outcomes and especially poor general health perception. Prospective longitudinal research is needed to examine the directionality of the relationships between ACEs, sleep quality, and physical and mental health outcomes over time.

Prenatal and early life origins of adolescence sleep problems: evidence from a birth cohort

PURPOSE

This study aims to identify the prenatal and early life predictors of adolescence sleep problems.

METHODS

Sleep data (n = 5081) from the 14-year (13.92 ± 0.34 years) follow-up of a birth cohort were analyzed to explore the predictors of adolescence trouble sleeping, nightmares, snoring and sleep talking/walking. Data from the antenatal period till adolescence were explored for identifying predictors of adolescence sleep problems. Modified Poisson regression with a robust error variance was used to identify significant predictors.

RESULTS

Our results suggest that about a quarter of adolescents in our study sample had sleep maintenance problems (nightmares: 27.88%, snoring: 23.20%, sleepwalking/talking 27.72%). The prevalence rate of sleep initiation problems was even higher (trouble sleeping: 40.61%). Our results suggest that antenatal and early-life factors, e.g. maternal smoking, anxiety, sleep problems in childhood, attention deficit hyperactivity disorder (ADHD) symptoms, and poor health are significant predictors of adolescence sleep problems.

CONCLUSIONS

This study demonstrates the predictive role of prenatal and early life risk factors in adolescence sleep problems. It seems that exposure to prenatal and early life risk factors increase the vulnerability for sleep problems later in life, which is further supported by poor health and lifestyle choices in adolescence. Therefore, close observation and mitigation of factors associated with early life risk factors could be a potential strategy for preventing sleep problems later in life.

Comparing the Experience of and Factors Perpetuating Chronic Insomnia Severity Among Young, Middle-Aged, and Older Adults

The prevalence of chronic insomnia is on the rise among young, middle-aged, and older adults. This secondary data analysis examined age-group differences in the experience of and factors perpetuating insomnia severity. Pretest data, obtained from a trial of behavioral interventions, were collected from 742 participants, using psychometrically sound measures of perpetuating factors (sleep habits, unhelpful beliefs, presleep arousal), insomnia experience (symptoms, perceived severity), and consequences or impact on daytime functioning. The age groups reported different insomnia symptoms (difficulty maintaining sleep in older adults) and impact on daytime functioning (poorer in older adults), but the same level of perceived insomnia severity. Unhelpful beliefs about sleep predicted insomnia severity in all age groups, and presleep arousal contributed to insomnia in young adults. The results highlight the importance of adequately managing chronic insomnia to minimize its impact on daytime functioning in all age groups, and of tailoring therapy to their experiences.

The effects of maternal risk factors during pregnancy on the onset of sleep difficulties in infants at 3 months old

Sleep problems in young children are among the most common concerns reported to paediatricians. Sleep is thought to have important regulatory functions, and sleep difficulties in early childhood are linked to several psychosocial and physiological problems. Moreover, several prenatal factors have been found to influence infants' sleep. Among them, most of the studies have been focused on maternal prenatal depression and/or anxiety as potential risk factors for sleep problems in childhood, whereas other relevant psychological factors during pregnancy have not received as much attention. Therefore, we aimed to examine the effect of several psychiatric maternal risk factors during pregnancy (i.e. symptoms of anxiety, depression, insomnia, alcohol use, seasonality, attention deficit and hyperactivity disorder and/or stressful life events) on the onset of some sleep problems related to sleep quality and sleep practices in 3-month-old infants. We examined 1,221 cases from a population-based birth cohort, with subjective measures during pregnancy in mothers, and at 3 months after birth in the infants. The findings showed that all the maternal risk factors during pregnancy, except for symptoms of alcoholism and sleepiness, were related to sleep difficulties in infants. Interestingly, attention deficit and hyperactivity disorder symptomatology in mothers during pregnancy was the only variable that predicted more than two sleeping difficulties (i.e. long sleep-onset latency, co-sleeping with parents and irregular sleeping routines) at 3 months old. Our results highlight the relevance of maternal risk factors during pregnancy, and not only prenatal depression and/or anxiety, as variables to be considered when examining sleep difficulties in infants.

Beneficial effects of environmental enrichment on behavior, stress reactivity and synaptophysin/BDNF expression in hippocampus following early life stress

Exposure to environmental enrichment can beneficially influence the behavior and enhance synaptic plasticity. The aim of the present study was to investigate the mediated effects of environmental enrichment on postnatal stress-associated impact with regard to behavior, stress reactivity as well as synaptic plasticity changes in the dorsal hippocampus. Wistar rat pups were submitted to a 3 h maternal separation (MS) protocol during postnatal days 1-21, while another group was left undisturbed. On postnatal day 23, a subgroup from each rearing condition (maternal separation, no-maternal separation) was housed in enriched environmental conditions until postnatal day 65 (6 weeks duration). At approximately three months of age, adult rats underwent behavioral testing to evaluate anxiety (Elevated Plus Maze), locomotion (Open Field Test), spatial learning and memory (Morris Water Maze) as well as non-spatial recognition memory (Novel Object Recognition Test). After completion of behavioral testing, blood samples were taken for evaluation of stress-induced plasma corticosterone using an enzyme-linked immunosorbent assay (ELISA), while immunofluorescence was applied to evaluate hippocampal BDNF and synaptophysin expression in dorsal hippocampus. We found that environmental enrichment protected against the effects of maternal separation as indicated by the lower anxiety levels and the reversal of spatial memory deficits compared to animals housed in standard conditions. These changes were associated with increased BDNF and synaptophysin expression in the hippocampus. Regarding the neuroendocrine response to stress, while exposure to an acute stressor potentiated corticosterone increases in maternally-separated rats, environmental enrichment of these rats prevented this effect. The current study aimed at investigating the compensatory role of enriched environment against the negative outcomes of adverse experiences early in life concurrently on emotional and cognitive behaviors, HPA function and neuroplasticity markers.

Combining Human Epigenetics and Sleep Studies in Caenorhabditis elegans: A Cross-Species Approach for Finding Conserved Genes Regulating Sleep

Study Objectives

We aimed to test a combined approach to identify conserved genes regulating sleep and to explore the association between DNA methylation and sleep length.

Methods

We identified candidate genes associated with shorter versus longer sleep duration in college students based on DNA methylation using Illumina Infinium HumanMethylation450 BeadChip arrays. Orthologous genes in Caenorhabditis elegans were identified, and we examined whether their loss of function affected C. elegans sleep. For genes whose perturbation affected C. elegans sleep, we subsequently undertook a small pilot study to re-examine DNA methylation in an independent set of human participants with shorter versus longer sleep durations.

Results

Eighty-seven out of 485,577 CpG sites had significant differential methylation in young adults with shorter versus longer sleep duration, corresponding to 52 candidate genes. We identified 34 C. elegans orthologs, including NPY/flp-18 and flp-21, which are known to affect sleep. Loss of five additional genes alters developmentally timed C. elegans sleep (B4GALT6/bre-4, DOCK180/ced-5, GNB2L1/rack-1, PTPRN2/ida-1, ZFYVE28/lst-2). For one of these genes, ZFYVE28 (also known as hLst2), the pilot replication study again found decreased DNA methylation associated with shorter sleep duration at the same two CpG sites in the first intron of ZFYVE28.

Conclusions

Using an approach that combines human epigenetics and C. elegans sleep studies, we identified five genes that play previously unidentified roles in C. elegans sleep. We suggest sleep duration in humans may be associated with differential DNA methylation at specific sites and that the conserved genes identified here likely play roles in C. elegans sleep and in other species.

Does preterm period sleep development predict early childhood growth trajectories?

OBJECTIVE

The current study examined the relationship between sleep state development across the preterm and early post-term periods and subsequent growth trajectories from 1 to 27 months corrected age.

STUDY DESIGN

Retrospective analysis of data collected prospectively from 111 preterm infants (⩽34 weeks gestation) who participated in a multi-site longitudinal study. Separate longitudinal parallel process models were calculated for each sleep state (active and quiet sleep) and growth (weight, length and body mass index (BMI) Z-scores) variable to estimate the associations between their developmental trajectories.

RESULTS

Significant associations were identified between the trajectories of quiet sleep and weight, active sleep and weight, quiet sleep and BMI, and active sleep and BMI. No statistically meaningful associations were identified between the trajectories of early childhood length and the preterm sleep states.

CONCLUSION

Faster preterm period sleep development appears to predict more favorable early childhood growth trajectories, particularly for weight, indicating preterm sleep may be an important biomarker for subsequent growth outcomes.

Stress and Androgen Activity During Fetal Development

Prenatal stress is known to alter hypothalamic-pituitary-adrenal axis activity, and more recent evidence suggests that it may also affect androgen activity. In animal models, prenatal stress disrupts the normal surge of testosterone in the developing male, whereas in females, associations differ by species. In humans, studies show that (1) associations between prenatal stress and child outcomes are often sex-dependent, (2) prenatal stress predicts several disorders with notable sex differences in prevalence, and (3) prenatal exposure to stressful life events may be associated with masculinized reproductive tract development and play behavior in girls. In this minireview, we examine the existing literature on prenatal stress and androgenic activity and present new, preliminary data indicating that prenatal stress may also modify associations between prenatal exposure to diethylhexyl phthalate, (a synthetic, antiandrogenic chemical) and reproductive development in infant boys. Taken together, these data support the hypothesis that prenatal exposure to both chemical and nonchemical stressors may alter sex steroid pathways in the maternal-placental-fetal unit and ultimately alter hormone-dependent developmental endpoints.