Associations between bedtime and nighttime parenting and infant cortisol in the first year

Development of 24-Hour Rhythms in Cortisol Secretion Across Infancy: A Systematic Review and Meta-Analysis of Individual Participant Data

CONTEXT

In adults, cortisol levels show a pronounced 24-hour rhythm with a peak in the early morning. It is unknown at what age this early-morning peak in cortisol emerges during infancy, hampering the establishment of optimal dosing regimens for hydrocortisone replacement therapy in infants with an inborn form of adrenal insufficiency.

OBJECTIVE

We aimed to characterize daily variation in salivary cortisol concentration across the first year of life.

METHODS

We conducted a systematic review followed by an individual participant data meta-analysis of studies reporting on spontaneous (ie, not stress-induced) salivary cortisol concentrations in healthy infants aged 0-1 year. A one-stage approach using linear mixed-effects modeling was used to determine the interaction between age and time of day on cortisol concentrations.

RESULTS

Through the systematic review, 54 eligible publications were identified, reporting on 29 177 cortisol observations. Individual participant data were obtained from 15 study cohorts, combining 17 079 cortisol measurements from 1904 infants. The morning/evening cortisol ratio increased significantly from 1.7 (95% CI: 1.3-2.1) at birth to 3.7 (95% CI: 3.0-4.5) at 6 to 9 months (P < .0001). Cosinor analysis using all available data revealed the gradual emergence of a 24-hour rhythm during infancy.

CONCLUSION

The early-morning peak in cortisol secretion gradually emerges from birth onwards to form a stable morning/evening ratio from age 6 to 9 months. This might have implications for hydrocortisone replacement therapy in infants with an inborn form of adrenal insufficiency.

Maternal depressive symptoms and mother-infant cosleeping (including room sharing and bedsharing): a systematic review

STUDY OBJECTIVES

Maternal depressive symptoms (MDS) affect most women during the first year postpartum. Mothers provide most of the nighttime care for infants, so studying the relationship between MDS and infant sleep location (ISL) is highly relevant to understanding maternal mental health over the first year of life and beyond. Infant sleep is studied by anthropologists, health care providers, and psychologists, with very little communication across disciplines. This review aimed to determine whether there is a predictive relationship between MDS and ISL.

METHODS

This systematic review searched 6 databases with terms related to maternal mood and ISL. Final analysis included 14 published studies, analyzed with narrative synthesis and Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included studies directly compared ISL and MDS.

RESULTS

Five studies showed no relationship between ISL and MDS, and 1 study found bedsharing reduced MDS. Five studies found cosleeping was related to higher MDS although directionality is mixed or missing, and 3 studies found an association at some ages or for some populations only. Examining studies according to type of infant sleep assessment, study design, age of infant, or breastfeeding status failed to detect consistent patterns.

CONCLUSIONS

A variety of study designs, types and definitions of variable measures, sample recruitment, and study outcomes prevent detection of a consistent relationship between MDS and ISL. We explore reasons for the elusive nature of a relationship and make recommendations for future research in MDS and ISL, including crossdisciplinary collaborations.

CITATION

Barry ES, D'Souza L. Maternal depressive symptoms and mother-infant cosleeping (including room sharing and bedsharing): a systematic review. J Clin Sleep Med. 2024;20(9):1517-1533.

Children's nocturnal awakenings and sleep duration during the first two years of life in the NASCITA cohort study

PURPOSE

Previous studies have analyzed the characteristics and prevalence of sleep disturbances among Italian children. Less attention has been paid, however, to the factors involved in sleep disturbances in the first two years of life. The goals of the present study were, therefore: 1) to provide a developmental trajectory of Italian infants' night awakenings and duration during the first two years of life and 2) to analyze which factors affect night awakenings the most over time.

METHODS

Data for this study were collected in the NASCITA cohort. During the well-child visits conducted at 6, 12, and 24 months, pediatricians asked parents to report if the child had any sleep disturbances, especially frequent night awakenings. Univariate and multivariable analyses were performed to test the association between child and family variables and the likelihood of frequent awakenings.

RESULTS

2973 toddlers, out of 5054 initially enrolled newborns, were included in this study; 875 (29.4 %) of whom presented frequent awakenings in at least one visit (peak of prevalence of 19.8 % at 12 months). Bed-sharing (adjusted OR 2.53; 95%CI:2.05-3.12) and living in the northern Italy (aOR 2.25; 95%CI:1.80-2.81) were the variables more strongly associated with an increased likelihood of frequent awakenings in the binomial logistic regression, while sleeping alone was associated with a decreased chance (aOR 0.62; 95%CI 0.45-0.89). A short sleep duration (<11 h/day) was reported for 801 (26.9 %) at 12 months, for 743 (25.0 %) at 24 months of age; in 383 cases, the short sleep duration was reported at both time points. An association was observed between frequent awakenings at 12 or 24 months and short sleep duration (OR 1.23; 95%CI 1.05-1.44 -ꭓ2 6.25, p = 0.012).

CONCLUSIONS

The current study identified some early predictors of frequent awakenings during the first two years of life. Since optimal sleep practices in children are essential for their development, effective, early interventions must be defined and integrated into pediatric care practices.

Insomnia in Children with Autism Spectrum Disorder: A Cross-Sectional Study on Clinical Correlates and Parental Stress

Insomnia is one of the most common co-occurring disorders in children with autism spectrum disorder (ASD). The purpose of this cross-sectional cohort study of 270 children with ASD was to assess the prevalence of insomnia using the Pediatric Sleep Clinical Global Impression Scale and to correlate sleep problems with cognitive level, adaptive behavior, parental stress, behavioral and emotional problems, and severity of core symptoms. Our findings revealed that one-third of children had insomnia and were related to reduced adaptive behaviors and higher levels of parental stress and behavioral and emotional problems. Insomnia must be evaluated in children with ASD to define an appropriate intervention to potentially alleviate the severity of clinical correlates and parental burden.

Associations between parental involvement at bedtime and young children's evening cortisol and nighttime sleep

Parents are theorized to play an important role in helping young children to downregulate arousal to achieve sufficient and good-quality sleep. To my knowledge, however, the links between parenting and children's physiological arousal at bedtime and subsequent nighttime sleep have not been empirically tested. The present study examined 3- to 6-year-old children's evening cortisol levels as a pathway linking parental involvement at bedtime to children's nighttime sleep duration and quality. Fifty-one children (53% male, 47% female; 80% White, 18% Biracial, 2% Black) and their families participated. Parental involvement (presence, contact, quiet activities) was assessed by raters from video recordings of one night of bedtime. Children's evening cortisol levels were measured from saliva samples taken at bedtime by parents across three nights. Children's nighttime sleep (minutes, efficiency) was determined from an actigraph worn the same three nights. Path analyses controlling for child and family demographics provided support for three significant indirect effects: lower child evening cortisol acted as a pathway linking greater parental presence at bedtime to more child nighttime sleep minutes and higher sleep efficiency, and lower child evening cortisol also linked greater parental contact at bedtime to higher sleep efficiency. Among this low-risk sample, the findings suggest that encouraging parental involvement in young children's bedtime routine may promote healthy sleep by way of reduced child physiological arousal.

Infant sleep as a topic in healthcare guidance of parents, prenatally and the first 6 months after birth: a scoping review

BACKGROUND

This scoping review focuses on infant sleep-related factors and themes that are relevant when health practitioners provide preventive health services to expectant and new parents.

METHODS

A systematic literature search in CINAHL, PubMed, and PsycINFO, published in 2010 or later, identified 1661 records. The search was further narrowed to focus on sleep in healthy term-born infants until the second half of the first year of life. A blinded review by both authors covered 136 papers, of which 43 papers were reviewed in the full text. Finally, 38 articles were included in the data extraction.

RESULTS

The analysis process showed that the selected studies formed three main information categories: 11 studies thematised safe infant sleep issues, 10 studies described design and findings from sleep-related intervention studies, and 17 studies focused on different parent-child interactive aspects that may influence the quality and duration of infant sleep in the first six months of life. The main finding is that knowledge about early infant sleep is very complex, and includes both child, parent, and environmental factors. Several studies have shown that the concepts and factors related to safe infant sleep also influence the development of healthy infant sleep patterns. Thus, these aspects are interwoven with each other and should be addressed together in communication with parents.

CONCLUSIONS

Health practitioners with different professional backgrounds need to search for an agreement on when and how different aspects of sleep-related knowledge should be communicated to new and expectant parents to enable the design of national follow-up programs. Parents want coherent and personalized services regarding infant sleep issues that may allow them to choose sleeping arrangements, routines, and behaviors that fit in with their sociocultural attitudes and traditions. Many different sources and formats may be used to empower parents regarding infant sleep issues. Studies have described the use of group or individual meetings, videos, and written materials. The key issue is the importance of consistent and seamless knowledge-based services.

Using complexity science to understand the role of co-sleeping (bedsharing) in mother-infant co-regulatory processes

Human infants spend most of their time sleeping, but over the first few years of life their sleep becomes regulated to coincide more closely with adult sleep (Galland et al., 2012; Paavonen et al., 2020). Evidence shows that co-sleeping played a role in the evolution of infant sleep regulation, as it is part of an ancient behavioral complex representing the biopsychosocial microenvironment in which human infants co-evolved with their mothers through millions of years of human history (Ball, 2003; McKenna 1986, 1990). This paper is a conceptual, interdisciplinary, integration of the literature on mother-infant co-sleeping and other mother-infant co-regulatory processes from an evolutionary (biological) perspective, using complexity science. Viewing the mother-infant dyad as a "complex adaptive system" (CAS) shows how the CAS fits assumptions of regulatory processes and reveals the role of the CAS in the ontogeny of mother-infant co-regulation of physiological (thermoregulation, breathing, circadian rhythm coordination, nighttime synchrony, and heart rate variability) and socioemotional (attachment and cortisol activity) development.

Do responsive sleep interventions impact mental health in mother/infant dyads compared to extinction interventions? A pilot study

Methods to improve sleep in infants commonly involve some ignoring (extinction) but are often unpopular with mothers worried about infant distress when left to cry. Alternative more responsive methods are needed. This pilot study evaluated stress, maternal depressive symptomology and sleep in mother/infant dyads, between Responsive, Controlled Crying and Control groups. From 199 mother/infant dyads from any cultural background, 41 infants 4-12 months were randomly allocated to Responsive (RG, n = 15), Controlled Crying (CCG, n = 18) or Controls (Treatment as Usual, TAUG, n = 8), with 10 withdrawing after randomisation. Infant sleep (7-day sleep diaries) and stress (oral cortisol on two nights), maternal self-reported stress (Subjective Units of Distress, SUDS), maternal perceived infant distress (MPI-S) and symptoms of maternal depression (Edinburgh Post-natal Depression Scale, EPDS) were measured four times across 8 weeks. Sleep duration was not different between groups but Responsive woke less (p = .008). There were no differences in cortisol between groups across time points. Maternal SUDS was positively correlated with infant cortisol and MPI-S (p < 0.05) and mothers in the Responsive group were significantly less stressed (p = 0.02) and reported less symptoms of depression (p < 0.05). Findings in this small sample show Responsive methods are comparable to the extinction (Controlled Crying) in sleep outcomes but from a relational and maternal mental health perspective, are less stressful, offering families potential choices of sleep interventions.

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.

Neurobiological limits and the somatic significance of love: Caregivers' engagements with neuroscience in Scottish parenting programmes

While parents have long received guidance on how to raise children, a relatively new element of this involves explicit references to infant brain development, drawing on brain scans and neuroscientific knowledge. Sometimes called 'brain-based parenting', this has been criticised from within sociological and policy circles alike. However, the engagement of parents themselves with neuroscientific concepts is far less researched. Drawing on 22 interviews with parents/carers of children (mostly aged 0-7) living in Scotland, this article examines how they account for their (non-)use of concepts and understandings relating to neuroscience. Three normative tropes were salient: information about children's processing speed, evidence about deprived Romanian orphans in the 1990s, and ideas relating to whether or not children should 'self-settle' when falling asleep. We interrogate how parents reflexively weigh and judge such understandings and ideas. In some cases, neuroscientific knowledge was enrolled by parents in ways that supported biologically reductionist models of childhood agency. This reductionism commonly had generative effects, enjoining new care practices and producing particular parent and infant subjectivities. Notably, parents do not uncritically adopt or accept (sometimes reductionist) neurobiological and/or psychological knowledge; rather, they reflect on whether and when it is applicable to and relevant for raising their children. Thus, our respondents draw on everyday epistemologies of parenting to negotiate brain-based understandings of infant development and behaviour, and invest meaning in these in ways that cannot be fully anticipated (or appreciated) within straightforward celebrations or critiques of the content of parenting programmes drawing on neuropsychological ideas.

Poverty, Caregiving, and HPA-Axis Activity in Early Childhood

The association between poverty and the activity of the hypothalamic pituitary adrenal (HPA) axis in early childhood is well established. Both ecological and transactional theories suggest that one way in which poverty may influence children's HPA-axis activity is through its effects on parents' behaviors, and over the past three decades a substantial literature has accumulated indicating that variations in these behaviors are associated with individual differences in young children's HPA-axis activity. More recent research suggests that non-parental caregiving behaviors are associated with HPA-axis activity in early childhood as well. Here we systematically review the literature on the association between both parental and non-parental caregiving behaviors in the context of poverty and the activity of the HPA-axis in early childhood. We conclude by noting commonalities across these two literatures and their implications for future research.

Reciprocal Relations Between Parental Problem Drinking and Children's Sleep: The Role of Socioeconomic Adversity

Reciprocal relations between parental problem drinking (PPD) and children's sleep were examined longitudinally, and socioeconomic status was considered as a moderating variable. At Wave 1, 280 children (Mage  = 10.33) and their parent(s) participated, and 275 families returned 1 year later. At both waves, parent(s) reported on PD and children wore actigraphs that measured established sleep parameters. After controlling for autoregressive effects, fathers' PD predicted reduced sleep duration and efficiency in children over time. Supportive of reciprocal effects, more frequent long wake episodes predicted greater PPD. Fathers' PD was a more robust risk factor for lower than higher income children. Results build on a growing literature that has considered children's sleep in a family context.

Parental Mental Health, Fathers' Involvement and Bedtime Resistance in Infants

BACKGROUND

Around the age of 6 months, difficulties in settling to sleep and frequent night awakenings are generally occurring in 20 to 30% of infants. According to the transactional model parental factors can play a significant role in influencing infant sleep development. The purpose of the current study was to explore the combined effect of infants' factors (temperament and sleep onset problems), and parental factors (parental mental health in terms of post-partum affective disorders, consistent bedtime routines and fathers' involvement at bedtime), on infant bedtime difficulties (e.g. fussing, crying or protesting), including both maternal and paternal perspectives.

METHODS

Sixty Italian intact two-parent families of infants (34 boys and 26 girls) ageing from 8 to 12 months (M = 10.73, SD = 2.54) were enrolled in the study. The parents filled out self-report questionnaires to measure the aforementioned variables. To investigate which infant and parental factors predicted infants' bedtime difficulties, two multiple linear regressions (MR), one for fathers and one for mothers, and relative weight analyses (RWA) were conducted.

RESULTS

With regard to infants' bedtime difficulties reported by fathers (R2 = .35) they were explained by infant involvement in constant bedtime routines (β = -.35, p = .030) and paternal involvement at bedtime (β = -.45, p = .007). Instead infants' bedtime difficulties reported by mothers (R2 = .32) were explained by minutes the child taken to fall asleep (β = .24, p = .04), infant involvement in constant bedtime routines (β = -.31, p = .01) and bedtime paternal involvement (β = -.27, p = .05).

CONCLUSIONS

The main results of this study emphasized the protective role of consistent bedtime routines and bedtime paternal involvement in reducing infants' bedtime difficulties perceived both from mothers and fathers. Future research could help to raise awareness and improve understanding of the familial influences on children's sleep, providing recommendations for educating families, school professionals, healthcare providers, and the general public on risk and protective factors that could play a meaningful role in infants and children's developing sleep patterns.

The influence of bed-sharing on infant physiology, breastfeeding and behaviour: A systematic review

This review aimed to better understand the underlying physiology of the risks and benefits of bed-sharing. Eight databases were searched using terms relating to adult-infant/baby, bed-sharing/co-sleeping combined with outcome terms for physiology, sleep, cardiovascular, respiratory, temperature and behaviour. Of 836 papers identified, 59 papers representing 48 cohorts met inclusion criteria. Objective data using various methodologies were available in 27 papers and subjective data in 32 papers. Diverse measures were reported using variable definitions of bed-sharing. Identified physiological and behavioural differences between bed-sharing and cot-sleeping included increased behavioural arousals, warmer in-bed temperatures and increased breastfeeding duration in bedshare infants as well as differences in infant overnight sleep architecture, cardiorespiratory control and cortisol responses to stress. We concluded that many differences are context-specific, and dependent on the subjective view of the parents and their cultural values. Objective risk arises if the infant is unable to mount an appropriate physiological or behavioural response to their micro-environment. More studies in the bed-sharing setting are needed to identify infant risk, the potential benefits of a safer environment, and how bed-sharing interacts with infant care practices other than sleep.

Parent-Infant Room Sharing During the First Months of Life: Longitudinal Links With Behavior During Middle Childhood

Current recommendations encourage parent–infant room sharing for the first 6 months of life. This longitudinal study (N = 193) is the first to examine long‐term relations of early room sharing with three domains of child behavior: sleep, behavior problems, and prosocial behavior. Information on room sharing was collected daily for infants’ first 6 months. At ages 6, 7, and 8 years, outcomes were assessed with maternal and teacher questionnaires and behavioral observations. Early room sharing was not related to sleep problems or behavior problems. Additionally, more weeks of room sharing were positively related to higher maternal ratings of child sleep quality and more prosocial behavior. In conclusion, early room sharing appears to be related to positive, but not negative, behavior outcomes in middle childhood.

Exploring sleep quality of young children with autism spectrum disorder and disruptive behaviors

BACKGROUND AND PURPOSE

Sleep disturbances in autism spectrum disorder (ASD) are common and may impair daytime functioning as well as add to parental burden. In this well characterized sample of young children with ASD and disruptive behaviors, we examine the association of age and IQ in sleep disturbances using the Child Sleep Habits Questionnaire modified for ASD (CSHQ-ASD). We also test whether children with poor sleep have greater daytime behavioral problems than those with better sleep. Finally, we examine whether parental stress is higher in children with greater disruptive behaviors and sleep disturbances.

PARTICIPANTS AND METHODS

One hundred and seventy-seven children with complete data out of 180 (mean age 4.7) with ASD participated in a randomized clinical trial. Parents completed the CSHQ-ASD and several other measures at study enrollment. The sample was divided into "poor sleepers" (upper quartile on the total score of the CSHQ-ASD) and "good sleepers" (lower quartile) for comparisons. Analyses were conducted to evaluate group differences on age, IQ, daytime disruptive behavior, social disability and parental stress.

RESULTS

The two groups of young children with ASD, good sleepers versus poor sleepers, were not different on age or cognitive level. Children in the poor sleeping group had significantly higher daytime behavioral problems including irritability, hyperactivity, social withdrawal and stereotypical behaviors. Parents in this group reported significantly higher levels of stress.

CONCLUSIONS

The finding of no age difference between good and poor sleepers in young children with ASD and disruptive behaviors suggests that sleep problems are unlikely to resolve as might be expected in typically developing children. Likewise, the good and poor sleepers did not significantly differ in IQ. These findings add strong support for the need to screen for sleep disturbances in all children with ASD, regardless of age and cognitive level. Poor sleepers exhibited significantly greater daytime behavioral problems and parents of children in this group reported significantly higher levels of stress. Above and beyond the co-occurring disruptive behavior, poor sleep quality appears to pose substantial additive burden on child and parents.

Family Functioning and Children's Sleep

Sleep is a pivotal correlate and predictor of many domains of child development, including socioemotional adjustment, physical health, and cognitive functioning. The family plays a major role in shaping children's sleep-wake behaviors, and developmental research on children's sleep in a family context is on the rise. As in any relatively young field, many gaps and questions remain. In this article, we aim to advance this literature by illustrating ways to examine the interconnections between family functioning and children's sleep. We also call for increasing conceptual developments and testing of transactional models, using well-established and psychometrically sound objective and subjective measures, and expanding both the family functioning domains and sleep parameters assessed.