Toward an Integrated Anthropology of Infant Sleep

Sleep characteristics and changes in sleep patterns among infants in Bhaktapur, Nepal

OBJECTIVE

Sleep undergoes major changes during the first year of life, but the characteristics of sleep among infants in low and middle-income countries are not well documented. This study describes sleep characteristics and changes in sleep patterns in infants at 6 and 12months of age from Bhaktapur, Nepal.

METHODS

This was a community-based longitudinal study comprising 735 infants. Sleep characteristics were obtained by interview with the mother using the Brief Infant Sleep Questionnaires. The stability of sleep duration and night awakenings were estimated by logistic regression analysis.

RESULTS

Cosleeping in the parent's bed at 6 and 12months of age was almost universal (>97%). At 6months of age, 254 (35%) and at 12months of age, 341 (46%) infants had a total 24-hour sleep duration <12 hours. Night awakenings >3 times per night were common (65%) both at 6 and 12months of age. Infants with frequent nightly awakenings at 6months had increased odds of frequent nightly awakenings at 12months (OR=2.2; 95% CI: 1.6, 2.9). Very few (<3%) mothers reported sleep problems in their infants at 6 and 12months of age.

CONCLUSIONS

Cosleeping was almost universal among Nepalese infants, and very few of the mothers reported sleep problems in their infants. Infants at 6 and 12months had similar patterns for both sleep duration and nocturnal awakenings. For infants, there were increased odds of having similar sleep duration and nocturnal awakening at 6 and 12months.

Infant Care: Predictors of Outdoor Walking, Infant Carrying and Infant Outdoor Sleeping

BACKGROUND

Although spending time outdoors is beneficial for development, little is known about outdoor time during infancy. The aim of this study was to assess frequencies and durations of (1a) outdoor walking and carrying in mother-infant dyads and (1b) infant outdoor sleeping in a stationary cot or pram. We furthermore aimed to identify associations of (2a) outdoor walking and carrying and (2b) infant outdoor sleeping, with infant, maternal and environmental sample characteristics.

METHODS

An online survey was distributed among mothers of 0- to 12-month-old infants. Initially, 1453 mothers were recruited, of which 1275 were included in the analyses. With respect to (1a) the outcomes of interest were: mother-infant dyads' total weekly duration of walking in minutes, frequency of walking on weekdays, as well as weekends, and the frequency of using an infant carrier during walks, as well as the daily duration of carrying in hours (indoors and outdoors together). With respect to (1b) the outcome variables were: placing the infant outdoors to sleep (yes/no), the total weekly duration of outdoor sleeping and the weekly frequency of outdoor sleeping. For aim 2, associations of the outcome variables with infant (i.e., age), maternal (i.e., working status) and environmental (i.e., house type) sample characteristics were assessed.

RESULTS

Mother-infant dyads engaged in walks for a total weekly duration of 201 min, for approximately one to three walks over weekdays (Monday through Friday), as well as one to three walks on the weekend. The infant carrier was used by 22% of mothers at least half of the time during outdoor walks, and 18% reported a daily duration of infant carrying of one hour or more. Among other associations, infant and maternal enjoyment of outdoor walking correlated positively with the duration as well as the frequency of walking during weekdays and during the weekend. Furthermore, employed mothers walked for a shorter duration and less frequently on weekdays as compared to mothers on maternity leave or mothers without a paid job. The availability of nearby recreational areas correlated positively with the weekly duration and frequency of walks. The infant carrier was used more frequently during outdoor walks if more than one child lived in the household. Infant carrying during outdoor walks was also related to infant behavior at night. Roughly a third of the mothers (29%) regularly had their infant sleep outdoors for a weekly duration of four hours and a weekly frequency of approximately one to two times. Younger infants, infants of mothers with higher education and infants living in detached houses were more likely to be placed outdoors to sleep.

DISCUSSION

We identified associations of infant, maternal and environmental characteristics with outdoor time spent during infancy. These results lay the foundation for future research on the effects of the outdoors on child development as well as on facilitators and barriers for caregivers.

Breastfeeding patterns in one-year-old children was not affected by a breastfeeding support intervention

BACKGROUND

Breastfeeding patterns in 12-month-old children play a central role in the mother-infant dyad, but studies describing the patterns are scarce.

AIM

To investigate breastfeeding patterns in 12-month-old infants before and after a breastfeeding support programme.

STUDY DESIGN

A baseline/intervention design as part of a larger implementation project aiming to revive the Ten Steps to Successful Breastfeeding programme.

SUBJECTS

During a 24-h period, 28 mothers from a baseline group and 24 mothers from an intervention group recorded all breastfeeding sessions on a pen and paper form.

RESULTS

The median (range) frequency of breastfeeding sessions was 6 (1-22) in the baseline group and 7 (1-20) times per 24 h in the intervention group. No significant difference was observed in frequencies between the two groups. The majority of children (57 % in the baseline group and 62 % in the intervention group) exhibited a pattern classified as partial breastfeeding, engaging in breastfeeding 6 or more times per 24 h throughout a substantial part of the day. A second pattern was classified as token breastfeeding, with few breastfeeding sessions, suggesting that breastfeeding occurred primarily for comfort.

CONCLUSION

This study illuminates the breastfeeding behaviours of 12-month-old children and can serve to normalise frequent breastfeeding patterns, potentially aiding mothers who wish to continue breastfeeding beyond infancy. The findings indicate no difference between the groups, suggesting that the implemented intervention did not influence maternal breastfeeding practices at one year of age. This underscores the potential necessity for prolonged support for parents throughout the breastfeeding period. ISRCTN registry: doi.org/10.1186/ISRCTN91972905.

Construction of the Views oN Infant Sleep (VNIS) Questionnaire

Parents' beliefs about infant sleep behaviour vary over time and across cultures. No validated instrument exists to understand parents' pre- and postnatal views on infant sleep behaviours, which may influence their caregiving decisions. The Views oN Infant Sleep Questionnaire (VNIS) will be a tool to assess parents' beliefs in order to facilitate tailored perinatal care, increase the reliability of postnatal self-report measures, allow for cross-cultural comparisons, and provide a baseline for researchers to use in longitudinal studies. We recruited an online sample of 971 female participants who were resident in the United Kingdom, at least 28 weeks pregnant, and at least 18 years of age. The initial questionnaire consisted of 31 questions about infant independence, night-waking, infant feeding, touch, and safety, and items were rated on a 5-point Likert scale. The item pool was reduced to 12 using principal component analysis and a structure was found for the three components "Closeness", "Independence", and "Night-waking". Overall, these results suggest that the VNIS can provide a brief scale to measure different aspects of individuals' beliefs about infant sleep. In further research the VNIS needs to be validated with a confirmatory factor analysis in another sample, and to be tested as a cross-cultural instrument.

Instrument development and an intervention to increase parents' self-efficacy regarding their infant's sleep

OBJECTIVE

Many Swedish parents experience that their infant has sleeping problems. Parents' self-efficacy regarding their infants' sleep may play an important role in how they perceive these problems. This pilot study aimed to develop an instrument measuring parents' self-efficacy regarding their infant's sleep and to examine if parents' self-efficacy was affected by an intervention focusing on parental education.

METHOD

Mothers and fathers, at a maternity unit in Sweden, were drawn into either an intervention (n = 46) or a control (n = 42) group. The intervention group received a home visit from a nurse who provided information about infant sleep; the importance of attachment; and advice regarding sleep, breastfeeding and bed sharing, including guidelines for safe bed sharing. Three months later, the participants answered questions on background data, breastfeeding, sleep and self-efficacy.

RESULTS

The 11-item two-factor Uppsala Parental Self-Efficacy about Infant Sleep Instrument (UPPSEISI) was constructed to measure parents' perceived self-efficacy. In adjusted analyses, being in the intervention group was associated with a higher self-efficacy (P = 0.035), as were being a mother (P = 0.003) and being satisfied with one's own sleep (P = 0.007), while parents' own sleeping problems were associated with a lower self-efficacy (P = 0.015).

CONCLUSION

Importantly, parental education may increase parents' self-efficacy regarding their infant's sleep.

Sleep tight! Adolescent sleep quality across three distinct sleep ecologies

Background and objectives

Good sleep quality, associated with few arousals, no daytime sleepiness and self-satisfaction with one's sleep, is pivotal for adolescent growth, maturation, cognition and overall health. This article aims to identify what ecological factors impact adolescent sleep quality across three distinct sleep ecologies representing a gradient of dense urbanity to small, rural environments with scarce artificial lighting and no Internet.

Methodology

We analyze variation of sleep efficiency, a quantitative measure of sleep quality-defined as the ratio of total time spent asleep to total time dedicated to sleep-in two agricultural indigenous populations and one post-industrial group in Mexico (Campeche = 44, Puebla = 51, Mexico City = 50, respectively). Data collection included actigraphy, sleep diaries, questionnaires, interviews and ethnographic observations. We fit linear models to examine sleep efficiency variation within and between groups.

Results

We found that sleep efficiency varied significantly across sites, being highest in Mexico City (88%) and lowest in Campeche (75%). We found that variation in sleep efficiency was significantly associated with nightly exposure to light and social sleep practices.

Conclusions and implications

Our findings point toward contextual cost-benefits of sleep disruption in adolescence. We highlight the need to prioritize research on adolescent sleep quality across distinct developmental ecologies and its impact on health to improve adolescent wellbeing through evidence-based health practices.

Contextual considerations in infant sleep: Offering alternative interventions to families

Infant sleep problems are one of the commonly reported reasons parents seek professional help, yet what constitutes a "sleep problem" depends on the models used to explain the development of infant sleep. The current models are based on research conducted in the western context where infant solitary sleeping is the norm. Parent-child co-sleeping is the norm in many cultures around the world. We argue that the primary focus of current research on parent-child interactions as the mediating context for the development of infant sleep problems has inherently made these models and ensuing interventions less sensitive and applicable to infant sleep problems in the context of co-sleeping families. When families present for help with infant sleep difficulties, extinction based behavioral interventions or interventions focused on reducing parental presence at bedtime are commonly recommended. These recommendations may not always align with cultural values and parenting practices of all families, therefore precluding these families from getting necessary help. In attempting to provide families with choices that depart from behavioral based interventions, this paper draws on research and adapts current models to propose an alternative to conceptualize perceptions of infant sleep problems that may be sensitive to and applied across various cultural and personal contexts. We attempt to provide a rationale for interventions that are inclusive and sensitive to families where reduced parental nighttime responsiveness may not be a preferred choice.

Hormone physiology and sleep dynamics among BaYaka foragers of the Congo Basin: Gendered associations between nighttime activity, testosterone, and cortisol

Sleep quality is an important contributor to health disparities and affects the physiological function of the immune and endocrine systems, shaping how resources are allocated to life history demands. Past work in industrial and post-industrial societies has shown that lower total sleep time (TST) or more disrupted nighttime sleep are linked to flatter diurnal slopes for cortisol and lower testosterone production. There has been little focus on these physiological links in other socio-ecological settings where routine sleep conditions and nighttime activity demands differ. We collected salivary hormone (testosterone, cortisol) and actigraphy-based sleep data from Congolese BaYaka foragers (N = 39), who have relatively short and fragmented nighttime sleep, on average, in part due to their typical social sleep conditions and nighttime activity. The hormone and sleep data collections were separated by an average of 11.23 days (testosterone) and 2.84 days (cortisol). We found gendered links between nighttime activity and adults' hormone profiles. Contrary to past findings in Euro-American contexts, BaYaka men who were more active at night, on average, had higher evening testosterone than those with lower nighttime activity, with a relatively flat slope relating nighttime activity and evening testosterone in women. Women had steeper diurnal cortisol curves with less disrupted sleep. Men had steeper cortisol diurnal curves if they were more active at night. BaYaka men often hunt and socialize when active at night, which may help explain these patterns. Overall, our findings indicate that the nature of nighttime activities, including their possible social and subsistence contexts, are potentially important modifiers of sleep quality-physiology links, meriting further research across contexts.

The impact of swaddling upon breastfeeding: A critical review

INTRODUCTION

Many parents swaddle their infants to promote sleep and reduce night-waking, however lack of definitive evidence about the pros and cons of swaddling when breastfeeding hinders postnatal recommendations regarding this infant care practice. This review critically examines research conducted on the impact of swaddling upon breastfeeding.

METHODS

Only two recent studies on swaddling outcomes have reported infant feed-type, therefore the purpose of this paper is to consider the known effects of swaddling on breastfeeding babies and their mothers. We interpret the existing literature on swaddling in terms of impact on breastfeeding physiology and behaviour during the immediate post-natal period, and as infancy progresses.

RESULTS

Infants swaddled immediately after birth show a delay in initial breastfeeding, less successful suckling at the breast, reduced intake of breastmilk and greater weight loss compared to un-swaddled babies. Swaddling visually obscures feeding cues and reduces crying, thereby eliminating two key feeding prompts typically used by parents/carers.

CONCLUSIONS

As swaddled babies cry less, and are fed less frequently than un-swaddled babies some clinical trials position swaddling as a 'novel weight regulation tool' to combat obesity. However, in the case of breastfed babies, by reducing feed frequency swaddling may impede maternal milk production and thereby infant growth.

ABM Clinical Protocol #37: Physiological Infant Care-Managing Nighttime Breastfeeding in Young Infants

A central goal of the Academy of Breastfeeding Medicine (ABM) is the development of clinical protocols for managing common medical problems that may impact breastfeeding success. These protocols serve only as guidelines for the care of breastfeeding mothers and infants and do not delineate an exclusive course of treatment or serve as standards of medical care. Variations in treatment may be appropriate according to the needs of an individual patient. The ABM empowers health professionals to provide safe, inclusive, patient-centered, and evidence-based care. Pregnant and lactating people identify with a broad spectrum of genders, pronouns, and terms for feeding and parenting. There are two reasons ABM's use of gender-inclusive language may be transitional or inconsistent across protocols. First, gender-inclusive language is nuanced and evolving across languages, cultures, and countries. Second, foundational research has not adequately described the experiences of gender-diverse individuals. Therefore, ABM advocates for, and will strive to use language that is as inclusive and accurate as possible within this framework. For more explanation, please read ABM Position Statements on Infant Feeding and Lactation-Related Language and Gender (https://doi.org/10.1089/bfm.2021.29188.abm) and Breastfeeding As a Basic Human Right (https://doi.org/10.1089/bfm.2022.29216.abm).

Marketing of commercial milk formula: a system to capture parents, communities, science, and policy

Despite proven benefits, less than half of infants and young children globally are breastfed in accordance with the recommendations of WHO. In comparison, commercial milk formula (CMF) sales have increased to about US$55 billion annually, with more infants and young children receiving formula products than ever. This Series paper describes the CMF marketing playbook and its influence on families, health professionals, science, and policy processes, drawing on national survey data, company reports, case studies, methodical scoping reviews, and two multicountry research studies. We report how CMF sales are driven by multifaceted, well resourced marketing strategies that portray CMF products, with little or no supporting evidence, as solutions to common infant health and developmental challenges in ways that systematically undermine breastfeeding. Digital platforms substantially extend the reach and influence of marketing while circumventing the International Code of Marketing of Breast-milk Substitutes. Creating an enabling policy environment for breastfeeding that is free from commercial influence requires greater political commitment, financial investment, CMF industry transparency, and sustained advocacy. A framework convention on the commercial marketing of food products for infants and children is needed to end CMF marketing.

Breastfeeding: crucially important, but increasingly challenged in a market-driven world

In this Series paper, we examine how mother and baby attributes at the individual level interact with breastfeeding determinants at other levels, how these interactions drive breastfeeding outcomes, and what policies and interventions are necessary to achieve optimal breastfeeding. About one in three neonates in low-income and middle-income countries receive prelacteal feeds, and only one in two neonates are put to the breast within the first hour of life. Prelacteal feeds are strongly associated with delayed initiation of breastfeeding. Self-reported insufficient milk continues to be one of the most common reasons for introducing commercial milk formula (CMF) and stopping breastfeeding. Parents and health professionals frequently misinterpret typical, unsettled baby behaviours as signs of milk insufficiency or inadequacy. In our market-driven world and in violation of the WHO International Code for Marketing of Breast-milk Substitutes, the CMF industry exploits concerns of parents about these behaviours with unfounded product claims and advertising messages. A synthesis of reviews between 2016 and 2021 and country-based case studies indicate that breastfeeding practices at a population level can be improved rapidly through multilevel and multicomponent interventions across the socioecological model and settings. Breastfeeding is not the sole responsibility of women and requires collective societal approaches that take gender inequities into consideration.

The relationship between perinatal circadian rhythm and postnatal depression: an overview, hypothesis, and recommendations for practice

Postnatal depression (PND) is an important public health problem with far-reaching consequences for mothers, families, and society. Current treatment approaches tend to focus on the depressive symptoms of the mother. We propose the need for a shift in the conceptualisation of PND and its management, by focusing on circadian rhythm as an early manifestation of mother-infant synchrony. We have reviewed the relevant interdisciplinary literature to formulate a hypothesis and suggest recommendations for practice. We hypothesise that, after a mother’s circadian rhythm becomes ‘desynchronised’ immediately following birth, persistence of this disruption is implicated in the development of PND. This has important implications for novel treatment strategies in the critical and vulnerable postnatal period, for example the use of outdoor-based interventions and light.

Prevalence and Predictors of Postpartum Cosleeping Practices after Midwife-Led Births in the US

OBJECTIVE

To evaluate patterns of mother-infant sleeping behaviors among US-based mothers who received care from midwives and breastfed their infants the majority of time at 6 weeks postpartum.

STUDY DESIGN

Infant sleep locations were reported for 24 915 mother-infant dyads followed through 6 weeks postpartum, following midwife-led singleton births. Using data derived from medical records, we used multinomial logistic regression to identify predictors of sleep location.

RESULTS

The median maternal age was 31 years (IQR, 27-34 years). The majority were White (84.5%), reported having a partner or spouse (95%), had a community birth (87%), and reported bedsharing with their infant for part (13.2%) or most of the night (43.8%). In the adjusted analysis, positive predictors of always bedsharing included increasing maternal age (OR, 1.17; 95% CI, 1.13-1.21; per 5 years), cesarean birth (OR, 1.49; 95% CI, 1.18-1.86), Medicaid eligibility (OR, 1.76; 95% CI, 1.62-1.91), and maternal race/ethnicity (Black OR, 1.40 [95% CI, 1.09-1.79]; Latinx OR, 1.53 [95% CI, 1.35-1.74]; multiracial OR, 1.69 [95% CI, 1.39-2.07]). Negative predictors of bedsharing included having a partner/spouse (OR, 0.66; 95% CI, 0.56-0.77) and birth location in hospitals (OR, 0.56; 95% CI, 0.49-0.64) or birthing centers (OR, 0.48; 95% CI, 0.44-0.51). Partial breastfeeding dyads were less likely to bedshare than those who were exclusively breastfeeding (always bedsharing OR, 0.48 [95% CI, 0.41-0.56]; sometimes bedsharing OR 0.69 [95% CI, 0.56-0.83]).

CONCLUSIONS

These data suggest that cosleeping is common among US families who choose community births, most of whom exclusively breastfeed through at least 6 weeks.

The Effectiveness of Sleep Training: Fact or Fiction?

Introduction

In Western cultures, parents often view infant sleep as problematic. Family, friends, and doctors may advise parents to “sleep train” assuming it is safe and effective, without considering its possible side effects, including its impact on breastfeeding. Unfortunately, it may reduce night feeds and result in earlier supplementation or weaning. The larger question is whether sleep training is worth the risk (i.e., does it improve infant sleep?). Our goal was to examine the data on the effectiveness of sleep training interventions on infant/toddler sleep.

Methods

PubMed and Google Scholar were searched for specific terms to identify articles that included behavioral sleep interventions and objective measures of sleep pre-and postntervention. Two objective infant sleep measures were examined: Night wakings and total sleep duration. Articles were then reviewed for evidence of the effectiveness of these interventions to reduce night wakings and increase total sleep duration.

Results

Five articles were identified that met the criteria for inclusion. Overall, there was no evidence that sleep training improves infant sleep.

Applications for Practice

The claim that sleep training is effective in changing infant sleep is not warranted. Given the potential side effects on breastfeeding, parents should be cautioned about engaging these behavioral sleep interventions if they have breastfeeding goals they want to achieve.

Association Between Infant Sleep Location and Breastfeeding

Objective: Studies have shown that mothers sleeping with their babies have longer breastfeeding duration. Bedsharing (BS) is thought to be a risk factor for Sudden Infant Death Syndrome. The aim was to investigate the frequency of BS and roomsharing (RS) and the effect of those on breastfeeding during the first 2 years of life. Also to evaluate risk-bearing situations regarding sleep environment. Methods and Study Design: This is a cross-sectional study, with retrospective cohort features for the evaluation of some data. The setting was a Well-Child Clinic at Bakırköy Research and Training Hospital. The children were followed from the first month until survey. Feeding history was collected retrospectively from child health records. Parents were surveyed concerning sleeping location and sleeping arrangements with a questionnaire. The study encompassed 351 children and their families. Results: The rate of exclusive breastfeeding was found to be 50.2% for the first 6 months of life and BS increased in exclusively breastfed infants. When breastfeeding continued after 6 months, the trend of increased BS through months was observed. RS, BS, and breastsleeping rates were 80.6%, 22.8%, 56.1%, respectively, in the whole cohort. Working mothers and mothers >35 years of age were significantly more likely to bedshare. Cigarette smoking in BS parents was identified as a child health risk. Unsafe sleep environment was found in 72.4% of the group. Conclusions: BS increases breastfeeding for the first 6 months. Families need guidance on safe sleeping practices and should be advised regarding avoidable risks and unsafe situations in BS. Parents should be counseled to make informed decisions.

US fathers' reports of bonding, infant temperament and psychosocial stress based on family sleep arrangements

Background and objectives

Evolutionary-grounded sleep research has been critical to establishing the mutual dependence of breastfeeding and nighttime sleep proximity for mothers and infants. Evolutionary perspectives on cosleeping also often emphasize the emotional motivations for and potential benefits of sleep proximity, including for parent-infant bonding. However, this potential link between infant sleep location and bonding remains understudied for both mothers and fathers. Moreover, in Euro-American contexts bedsharing has been linked to family stress and difficult child temperament, primarily via maternal reports. We know relatively little about whether paternal psychosocial dynamics differ based on family sleep arrangements, despite fathers and other kin often being present in the cosleeping environment across cultures. Here, we aim to help address some of these gaps in knowledge pertaining to fathers and family sleep arrangements.

Methodology

Drawing on a sample of Midwestern U.S. fathers (N=195), we collected sociodemographic and survey data to analyze links between infant nighttime sleep location, paternal psychosocial well-being, father-infant bonding, and infant temperament. From fathers’ reports, families were characterized as routinely solitary sleeping, bedsharing, or roomsharing (without bedsharing).

Results

We found that routinely roomsharing or bedsharing fathers, respectively, reported stronger bonding than solitary sleepers. Bedsharing fathers also reported that their infants had more negative temperaments and also tended to report greater parenting-related stress due to difficulties with their children.

Conclusions

These cross-sectional results help to highlight how a practice with deep phylogenetic and evolutionary history, such as cosleeping, can be variably expressed within communities with the potential for family-dependent benefits or strains.

Evolutionary-grounded cosleeping research has elucidated the intimate connections between mother-infant sleep proximity and breastfeeding. However, some Euro-American research indicates that bedsharing can coincide with family strain and stress. Here, U.S. fathers who routinely roomshared or bedshared, respectively, reported stronger bonds to their babies than solitary sleeping fathers, but bedsharing fathers also reported more negative infant temperament.

Lost in translation-the influence of language on infant sleep research

OBJECTIVES

We consider whether language shapes cultural interpretations of sleep in the family context using ethnographic data from the Czech Republic to explore one of the methods employed by Czech parents in helping their children aged 0-3 years to fall asleep.

METHODS

Multi-methodological ethnographic data were collected in the Czech Republic during 2015-2018 with supplemental online data obtained in 2020. This involved focus groups with 90 participants in mother-baby centers, and interviews with 30 families, supplemented with 468 online responses.

RESULTS

In the Czech Republic the use of parental presence with or without physical contact to help a child to fall asleep is a widespread practice. It is well-embedded within Czech culture and referred to by a widely known term: Uspávání. Parents expressed multiple motivations for using Uspávání to help their child sleep.

DISCUSSION

Within much of the Anglophone sleep literature the practice of actively helping a child to fall asleep is perceived as problematic. A child who cannot fall asleep alone is considered to exhibit "behavioral insomnia of childhood," and parents are advised to prevent this "sleep problem" by promoting self-soothing techniques in infancy. We suggest that as there is no English-language equivalent for the word Uspávání the concept it encapsulates is under-valued by sleep researchers, and the practice and its consequences are insufficiently researched.

CONCLUSIONS

Some important variations in parental sleep practices that are embedded in everyday family systems lack English terminology; Uspávání is one such example. This may lead to researchers overlooking or rejecting the validity of such diverse family sleep practices. There is a need for more ethnographic research of sleep in the context of different cultural environments and family systems to explore how language constrains understanding of parent-child sleep.

The Human Sleep Paradox: The Unexpected Sleeping Habits of Homo sapiens

The human sleep pattern is paradoxical. Sleep is vital for optimal physical and cognitive performance, yet humans sleep the least of all primates. In addition, consolidated and continuous monophasic sleep is evidently advantageous, yet emerging comparative data sets from small-scale societies show that the phasing of the human pattern of sleep–wake activity is highly variable and characterized by significant nighttime activity. To reconcile these phenomena, the social sleep hypothesis proposes that extant traits of human sleep emerged because of social and technological niche construction. Specifically, sleep sites function as a type of social shelter by way of an extended structure of social groups that increases fitness. Short, high-quality, and flexibly timed sleep likely originated as a response to predation risks while sleeping terrestrially. This practice may have been a necessary preadaptation for migration out of Africa and for survival in ecological niches that penetrate latitudes with the greatest seasonal variation in light and temperature on the planet.

Does Bed Sharing with an Infant Influence Parents’ Sexual Life? A Scoping Review in Western Countries

Bed sharing—the sharing of a sleeping surface by parents and children—is a common, yet controversial, practice. While most research has focused on the public health aspect of this practice, much less is known regarding its effect on the marital relationship. The aim of the present study was to conduct a scoping review on the impact of parent–infant bed sharing sleeping practices on the sexual and marital relationship of couples. The qualitative synthesis of six studies on this topic suggests that overall, bed sharing does not exert a significant negative impact on family functioning; when it does, it appears to be related to incongruent parental beliefs and expectations, especially when bed sharing is not an intentional choice of sleep arrangement, and there are other confounding factors such as fatigue and psychological distress. Suggestions for future studies and clinical implications are discussed.

Parents matter: barriers and solutions when implementing behavioural sleep interventions for infant sleep problems

Behavioural sleep interventions (eg, extinction-based methods) are among the most efficacious evidence-based techniques in the treatment of infant sleep problems. However, behavioural sleep interventions can be challenging for families to successfully implement. This review aims to summarise current research surrounding the potential barriers that arise when clinicians attempt to implement extinction-based methods with parents of infants. We provide a model that summarises 3 types of contextual-barriers; socio-cultural barriers, parent barriers, and infant barriers. Based on the current evidence, we propose that adopting a stepped care approach, planning ahead, increasing support, motivational interviewing, and/or emotional regulation may serve as useful tools for parents when implementing extinction-based methods. By considering these techniques, more families may receive the benefits of improved infant sleep.

Quality of father-child relationships as a predictor of sleep developments during preschool years

Substantial developmental changes in sleep occur during the preschool period, but few studies have investigated the factors that forecast these developments. The aim of this study was to examine whether three aspects of father-child relationships in toddlerhood predicted individual differences in developmental patterns of change in five actigraphy-derived sleep variables during the preschool period (N = 67; sleep assessed yearly between 2 and 4 years). In a predominantly White and middle-to-higher income sample, paternal mind-mindedness and quality of father-child interactions were assessed during father-child free play at 18 months and fathers self-reported on their involvement in childrearing at age 2. Multilevel growth modeling revealed that children whose father made more mind-related comments during father-child interactions had a higher proportion of sleep taking place during nighttime as well as shorter daytime and total sleep duration at 2 years. This was, however, followed by a relative leveling off (i.e., less rapid change) of these sleep features between 2 and 4 years. Given previous studies documenting that nighttime sleep proportion increases while daytime and total sleep duration decrease during preschool years, the findings suggest that children who are exposed to more paternal mind-mindedness may reach more mature sleep patterns earlier in development.

Sleep Consolidation, Sleep Problems, and Co-Sleeping: Rethinking Normal Infant Sleep as Species-Typical

Infants evolved in the context of close contact (including co-sleeping). Evolutionary context is rarely considered in psychological infant sleep research, and Western sleep researchers make assumptions about what optimal "normal" infant sleep is and how to achieve early, deep, infant sleep consolidation and avoid infant sleep problems. However, an evolutionary and anthropological view of infant sleep as species-typical recognizes that human evolution likely prepared the infant brain for optimal development within its evolutionary context - co-sleeping. Thus, "normal" infant sleep, sleep consolidation, and sleep problems should all be understood within the framework of co-sleeping infants, not the historically new-phenomenon of solitary-sleeping infants. Much work needs to be done in order to understand "normal" infant sleep as species-typical and how adaptive infants are to environments that stray from their evolutionary norm.

Taking the sleep lab to the field: Biometric techniques for quantifying sleep and circadian rhythms in humans

OBJECTIVES

Remarkably, the specifics of sleep along the human lineage have been slow to emerge, which is surprising given our distinct mental and behavioral capacity and the importance of sleep for individual health and cognitive performance. Largely due to difficultly of measuring sleep outside a controlled, clinical, and laboratory study in ambulatory individuals, human biologists have yet to undergo a thorough examination of sleep in ecologically diverse settings. Here, I outline the procedures and methods for generating sleep data in a broader ecological context with the goal of facilitating the integration of sleep and circadian analyses into human biology research.

METHODS

I describe the steps involved in participant recruitment, screening by way of survey instruments, and sample collection. In addition to describing field use of the traditional (but invasive) equipment such as the gold-standard application of electroencephalography (EEG), I demonstrate leading-edge noninvasive techniques for biometric devices (ie, wrist-worn actigraphy, ring worn arterial pulsometry) to generate sleep and circadian rhythms data.

RESULTS

I outline best approaches to process and analyze data-including variables such as sleep duration, 24-hour sleep time (ie, summation of night and day sleep), sleep efficiency, sleep fragmentation, and nonparametric circadian rhythms analysis to quantify circadian amplitude. Finally, I discuss comparative statistical methods that are optimized for the use of time-series data.

CONCLUSIONS

This review serves as an introduction to the best practices for studying sleep-wake patterns in humans-with the goal of standardizing tools for launching new human sleep biology research initiatives across the globe.

Mother-Infant Co-Sleeping and Maternally Reported Infant Breathing Distress in the UK Millennium Cohort

Mother-infant co-sleeping or bed sharing is discouraged by health organisations due to evidence that it is associated with unexplained sudden infant death. On the other hand, there is evidence that it should theoretically be beneficial for infants. One line of this evidence concerns breathing regulation, which at night is influenced by the rocking movement of the mother's chest as she breathes. Here, the hypothesis that mother-infant co-sleeping will be associated with a lower probability of infant breathing distress is tested in the UK Millennium Cohort Study (n = 18,552 infants). Maternal, infant, family, and socio-economic covariates were included in logistic regression analysis, and in a machine learning algorithm (Random Forest) to make full use of the number of variables available in the birth cohort study data. Results from logistic regression analysis showed that co-sleeping was associated with a reduced risk of breathing difficulties (OR = 0.69, p = 0.027). The Random Forest algorithm placed high importance on socio-economic aspects of infant environment, and indicated that a number of maternal, child, and environmental variables predicted breathing distress. Co-sleeping by itself was not high in the Random Forest variable importance ranking. Together, the results suggest that co-sleeping may be associated with a modest reduction in risk of infant breathing difficulties.

What Is “Normal” Infant Sleep? Why We Still Do Not Know

The human need for sleep is universal and unquestioned; however, humans vary in their sleep needs according to age, individual differences, as well as cultural and social norms and practices. Therefore, what is “normal” in infant sleep and the development of sleep architecture in humans is highly dependent on biological and sociocultural variables as well as socially constructed assumptions about what infant sleep “should” look like. This paper uses a multidisciplinary approach to review papers from fields including pediatrics, anthropology, psychology, medicine, and sociology to understand “normal” infant sleep. Because human culture and behavioral practice changes much more quickly than evolved human biology, and because human evolutionary history occurred in the context of breastfeeding and cosleeping, new work in the field of infant sleep architecture development would benefit from a multidisciplinary approach. To come to a consensus about what is “normal” infant sleep, researchers must agree on underlying basic assumptions of infant sleep from which to ask question and interpret findings.