Sleeping Through the Night: A Developmental Perspective

A preliminary study on the performance of the Nanit auto-videosomnography scoring system against observed video scoring and actigraphy to estimate sleep-wake states in infants

GOAL AND AIMS

To examine the performance of the Nanit auto-videosomnography scoring system as a measure of sleep-wake states in infants compared to observed video scoring and actigraphy.

FOCUS TECHNOLOGY

Nanit's auto-videosomnography scoring system.

REFERENCE

Observed video scoring and actigraphy.

SAMPLE

Sixteen U.S. infants (age: 4-8 months).

DESIGN

Infants' sleep was assessed with the Nanit camera and actigraphy (micromotion logger sleep watch). Fifty nights were included in the analyses. Nanit's videos were processed via a computer vision algorithm and were scored by trained observers. Actigraphic data were scored with the validated Sadeh algorithm.

CORE ANALYTICS

Bland-Altman plots and epoch-by-epoch analyses (sensitivity, specificity, and total accuracy).

ADDITIONAL ANALYTICS

Specificity values for each night separately.

CORE OUTCOMES

Nanit estimates of sleep minute were not significantly different from observed sleep minute, but Nanit overestimated sleep minute relative to actigraphy by 17 minutes. Nanit overestimated wake minutes (wake after sleep onset by 5.3 minutes relative to observed scoring and underestimated wake after sleep onset by 19.1 minutes relative to actigraphy. The epoch-by-epoch analyses revealed that Nanit reached 97.8% sensitivity in classifying sleep and 60.4% specificity in classifying wake compared to observed scoring. The rates compared to actigraphy were 99.3% for sensitivity and 51.7% for specificity.

IMPORTANT ADDITIONAL OUTCOMES

Specificity values were lower for infants with lower wake after sleep onset.

CORE CONCLUSION

This preliminary study suggests that Nanit is highly accurate in detecting infant sleep compared to observed scoring and actigraphy. Specificity values are within the range of those reported previously for actigraphy devices that are commonly used in pediatric sleep research.

Possible contribution of better maternal psychological well-being to the acquisition of sleeping through the night in infants during the early postpartum period

The objective of this study was to elucidate whether better maternal psychological well-being contributes to the acquisition of "sleeping through the night" (STN) in infants during the early postpartum period. Fifty-two primiparous mothers completed the General Health Questionnaire-28 (GHQ-28) in the third trimester (prenatal) and when the conceptional ages of their babies reached 8-9 weeks (hereafter, 2 months), 12-13 weeks (3 months), and 16-17 weeks (4 months). They also recorded babies' nocturnal sleep patterns in a timetable for 5 consecutive days each month postpartum. "Regular STN" was defined when the mean of longest nocturnal sleep duration for 5 consecutive days was > 8 h or between 6 and 8 h with < 1.0 nocturnal awakenings. According to these criteria, a total of 14 infants (27 %) acquired regular STN at 4 months (referred to as "STN infants"), with STN infants showing a marked increase in longest nocturnal sleep duration and a decrease in nocturnal awakenings from 2 to 3 months of age. The mothers of STN infants demonstrated steady reductions in postnatal GHQ-28 scores and had significantly lower prenatal GHQ-28 scores compared with the mothers of non-STN infants (3.7 ± 3.0 vs. 6.4 ± 4.1, p = 0.027). In random forest models for binomial classification, both prenatal and postnatal (at 4 months) GHQ-28 scores were identified as significant covariates for distinguishing STN infants, and other important covariates, including weeks of delivery, stepfamily, birth weight of the infant, and maternal co-sleeping at bedtime, were selected. Among these covariates, maternal co-sleeping at bedtime had relatively stronger correlations with both STN infants (r = - 0.440) and prenatal maternal GHQ-28 scores (r = 0.377). In conclusion, because prenatal maternal psychological well-being was thought to predict the acquisition of STN in infants, infants born from mothers with better psychological well-being appear to have some advantages in acquiring STN. These cross-lagged correlations suggest that the pathway from mothers to infants may be mediated by certain parenting behaviors, such as maternal co-sleeping at bedtime.

Exploring role of sleep aids in sleep problems in preschool children

It is well known that children use sleep aids, such as blankets or soft toys, at bedtime. However, there is a lack of understanding regarding the factors associated with their use and role in addressing sleep problems. This study investigated 96 Japanese children aged 40 to 47 months to examine these associations. We measured children's stress (through a questionnaire and salivary cortisol [cortisol awakening response]), anxiety symptoms, behavioral problems, and temperament, and created a model to predict the status of sleep aid use. Furthermore, we explored the association between sleep aid use and children's sleep problems as evaluated by their caregivers. We found that children who used sleep aids were more likely to experience anxiety symptoms. Moreover, most children used sleep aids even when they co-slept with their caregivers and/or siblings. Their use was not uniquely associated with sleep problems. These findings suggest that sleep aid serves as a defense against anxiety, including that caused by the absence of a caregiver, rather than as a substitute for a caregiver. Our study sheds light on their role and emphasizes the importance of viewing development within the complex interactive processes of humans and objects.

Sleep from Infancy Through Adolescence

This article describes the changes in normal sleep regulation, structure, and organization and sleep-related changes in respiration from infancy to adolescence. The first 2 years of age are striking, with more time asleep than awake. With development, the electroencephalogram architecture has a marked reduction in rapid eye movement sleep and the acquisition of K-complexes, sleep spindles, and slow-wave sleep. During adolescence there is a reduction in slow-wave sleep and a delay in the circadian phase. Infants have a more collapsible upper airway and lower lung volumes than older children, which predisposes them to obstructive sleep apnea and sleep-related hypoxemia.

Sleep patterns and intraindividual sleep variability in mothers and fathers at 6 months postpartum: a population-based, cross-sectional study

OBJECTIVES

Given that postpartum sleep is an important family process, further investigations including both mothers and fathers are necessary. The present study aimed to describe and compare sleep patterns and intraindividual night-to-night variability in mothers and fathers at 6 months postpartum using subjective and objective sleep measures.

DESIGN

Cross-sectional study.

SETTING

General community-based study in Montreal, QC, Canada.

PARTICIPANTS

Thirty-three couples (mothers and fathers) with no self-reported history of medical and mental health conditions participated in this study.

RESULTS

Parental sleep was measured across 10 consecutive nights using both a daily sleep diary and actigraphy. Results demonstrated that mothers' subjective and objective sleep was more fragmented compared with fathers (shorter longest consecutive sleep duration and more nocturnal awakenings; p<0.001). While mothers and fathers did not differ in their self-reported nocturnal sleep duration (p>0.05), actigraphy indicated that mothers obtained significantly longer nocturnal sleep duration (448.07 min±36.49 min) than fathers (400.96 min±45.42 min; p<0.001). Intraindividual sleep variability was revealed by relatively high coefficients of variation for parents across both subjective and objective indices related to sleep fragmentation (between 0.25 and 1.32). Actigraphy also demonstrated variability by mothers sleeping 6 hours consecutively on less than 3 nights, 27.27% (±22.81), and fathers on less than 6 nights, 57.27% (±24.53), out of 10. Associations were also found between parental sleep and family factors, such as age and infant sleep location (p<0.05).

CONCLUSIONS

These findings advance our knowledge of how sleep unfolds within the family system beyond the early postpartum weeks and/or months. Given the link between disturbed sleep and family functioning, the current research accentuates the importance of examining postpartum sleep patterns and variability in parents.

Developmental trajectories of infant nighttime awakenings are associated with infant-mother and infant-father attachment security

This longitudinal study examined developmental trajectories of infant sleep problems from 3 to 24 months old and investigated associations with infant-parent attachment security and dependency. In a sample of 107 Israeli families, number and duration of infant nighttime awakenings were measured at 3, 6, 9, and 24 months old, using mothers' and fathers' reports on the Brief Infant Sleep Questionnaire (BISQ). Infant-parent attachment security and infant-parent dependency was assessed at 24 months old, using the observer Attachment Q-Sort procedure (AQS) with both parents. Latent growth curve models showed a non-linear decline in number and duration of infant nighttime awakenings over time. A higher number and longer duration of infant nighttime awakenings at 3 months were associated with higher infant-father attachment security at 24 months. In contrast, longer infant nighttime awakenings at 3 months were predictive of lower infant-mother attachment security at 24 months. A steeper decrease in duration of infant nighttime awakenings was associated with higher infant-father attachment security and lower infant-mother attachment security. As a potential mechanism, paternal involvement in nighttime caregiving was explored in relation to infant-father attachment security. Results of our post-hoc analyses revealed no significant associations between paternal involvement in nighttime caregiving and infant-father attachment security. Our results highlight the need to examine potential mechanisms explaining the divergent associations of infant sleep problems with infant-mother and infant-father attachment security in future research.

Assessment of infant sleep: how well do multiple methods compare?

The current study compares sleep variables obtained from videosomnography, actigraphy, and sleep diaries, three of the most common sleep assessment methods used in infant sleep studies. Using a sample of 90 African American 3-month olds, we compare correlations and discrepancies for seven sleep variables across each of the three pairs of assessment methods for one night of a week-long sleep study. These seven variables are indicative of sleep schedule (e.g. sleep onset time, rise time), duration (e.g. sleep period, sleep time, wake time), and fragmentation (e.g. night wakings, longest sleep period). We find that across all sleep assessment methods, correlations are highest for variables indicative of sleep schedule, and lowest for variables indicative of sleep fragmentation. Comparing the magnitude and significance of the discrepancies, we find that actigraphy and sleep diaries significantly overestimate sleep period duration and underestimate the number of night waking episodes, compared with videosomnography. Actigraphy and sleep diaries were more concordant with one another than with videosomnography. Epoch-by-epoch analyses indicated that actigraphy had low sensitivity to detect wakefulness, compared with videosomnography. Contrary to our hypothesis, the discrepancies between sleep assessment methods did not vary widely based on infant sleep location (own room vs. parent's room) or sleep surface (own bed vs. parent's bed). Limitations and implications of these findings for future research are discussed.

Evaluating motion detection to score sleep disturbance for children: A translational approach to developing a measurement system

Information obtained via direct observation of children's sleep disturbance throughout the night in their home can guide the assessment and treatment process, but watching live or via recorded video might be impractical in terms of time expenditures. In Experiment 1, we assessed the accuracy and reliability of a motion-detection camera with human motor movements. In Experiment 2, we tested the system's generality by using it to obtain in-home measures of sleep disturbance for three children with autism spectrum disorder and compared the accuracy to a continuous measurement system. We also measured scoring efficiency and assessed parents' acceptability of the camera. Results provide preliminary support for motion detection in measuring sleep disturbance, but further evaluation of motion detection to improve accuracy is warranted.

Sleep findings in Brazilian children with congenital Zika syndrome

Study Objectives

Zika virus infection during pregnancy may result in congenital Zika syndrome (CZS), whose characteristics are being described.

Methods

The present study aimed to investigate the sleep characteristics of 136 infants/toddlers (88 with CZS and 48 with typical development (TD), age and gender matched, 60% girls and 40% boys in both groups) using the Brief Infant Sleep Questionnaire. The ages of children in both groups ranged from 5 to 24 months (CZS 15.9 ± 0.4 vs. TD 15.8 ± 1.0 months, P= 0.90).

Results

The results show that 34.1% of CZS and 2% of TD children were defined as poor sleepers, 15% of CZS and 2% of TD children remained awake at night for a period longer than 1 hour, and 24% of CZS and 2% of TD children slept less than 9 hours. The CZS group showed shorter total sleep time (CZS 11.24 ± 2.6 vs. TD 12.02 ± 1.9 hours, P= 0.03) and shorter nocturnal sleep duration than the TD group (CZS 8.2 ± 0.2 vs. TD 9.4 ± 0.2 hours, P= 0.0002). In contrast to the control group (P= 0.02, r= -0.34), in the CZS group, no correlation was found between age and nocturnal wakefulness. Future studies should explore these data in relation to the development and maturation of the central nervous system of these children.

Conclusions

Considering the well-known consequences of poor sleep quality on health in several populations, the presence of sleep disorders should be considered in CZS using multidisciplinary treatments.

Uninterrupted Infant Sleep, Development, and Maternal Mood

OBJECTIVES

Contrary to the importance of total sleep duration, the association between sleeping through the night and development in early infancy remains unclear. Our aims were to investigate the proportion of infants who sleep through the night (6- or 8-hour sleep blocks) at ages 6 and 12 months in a longitudinal cohort and to explore associations between sleeping through the night, mental and psychomotor development, maternal mood, and breastfeeding.

METHODS

At 6 and 12 months of age, maternal reports were used to assess the longest period of uninterrupted infant sleep and feeding method (n = 388). Two different criteria were used to determine if infants slept through the night: 6 and 8 hours of uninterrupted sleep. Mental and psychomotor developmental indices (Bayley Scales of Infant Development II) and maternal mood (Center for Epidemiologic Studies Depression Scale) were measured at 6, 12, and 36 months of age.

RESULTS

Using a definition of either 6 or 8 hours of uninterrupted sleep, we found that 27.9% to 57.0% of 6- and 12-month-old infants did not sleep through the night. Linear regressions revealed no significant associations between sleeping through the night and concurrent or later mental development, psychomotor development, or maternal mood (P > .05). However, sleeping through the night was associated with a much lower rate of breastfeeding (P < .0001).

CONCLUSIONS

Considering that high proportions of infants did not sleep through the night and that no associations were found between uninterrupted sleep, mental or psychomotor development, and maternal mood, expectations for early sleep consolidation could be moderated.

Parent-Implemented Bedtime Fading and Positive Routines for Children with Autism Spectrum Disorders

Sleep disorders affect a large portion of those with autism spectrum disorder. Behavioural interventions have been found to increase appropriate sleep behaviours. This study sought to examine the efficacy of two stimulus control interventions (bedtime fading and positive routines) on total sleep duration, sleep onset latency and frequency and duration of night wakings for children with autism using two multiple baseline designs. Secondary dependent variables, namely, educational opportunities, challenging behaviours, parent acceptance and social validity were also analysed. Results suggest some efficacy for both interventions. Increased total sleep duration and decreased sleep onset latency were achieved with bedtime fading. Positive routines showed mixed results with decreased sleep onset latency and increased total sleep duration for two of three participants.

Video evidence that parenting methods predict which infants develop long night-time sleep periods by three months of age

Aim

To examine two hypotheses about the longitudinal relationship between night-time parenting behaviours in the first few postnatal weeks and infant night-time sleep-waking at five weeks, three months and six months of age in normal London home environments.

Background

Most western infants develop long night-time sleep periods by four months of age. However, around 20–30% of infants in many countries continue to sleep for short periods and cry out on waking in the night: the most common type of infant sleep behaviour problem. Preventive interventions may help families and improve services. There is evidence that ‘limit-setting’ parenting, which is common in western cultures, supports the development of settled infant night-time behaviour. However, this evidence has been challenged. The present study measures three components of limit-setting parenting (response delay, feeding interval, settling method), examines their stability, and assesses the predictive relationship between each of them and infant sleep-waking behaviours.

Methods

Longitudinal observations comparing a General-Community (n=101) group and subgroups with a Bed-Sharing (n=19) group on infra-red video, diary and questionnaire measures of parenting behaviours and infant feeding and sleep-waking at night.

Findings

Bed-Sharing parenting was highly infant-cued and stable. General-Community parenting involved more limit-setting, but was less stable, than Bed-Sharing parenting. One element of General-Community parenting – consistently introducing a short interval before feeding – was associated with the development of longer infant night-time feed intervals and longer day-time feeds at five weeks, compared with other General-Community and Bed-Sharing infants. Twice as many General-Community infants whose parents introduced these short intervals before feeding in the early weeks slept for long night-time periods at three months of age on both video and parent-report measures, compared with other General-Community and Bed-Sharing infants. The findings’ implications for our understanding of infant sleep-waking development, parenting programmes, and for practice and research, are discussed.

Descriptive figures for differences in parenting and infant night-time distress in the first three months of age

Aim

To provide descriptive figures for infant distress and associated parenting at night in normal London home environments during the first three months of age.

Background

Most western infants develop long night-time sleep periods by four months of age. However, 30% of infants in many countries sleep for short periods and cry out on waking in the night: the most common type of infant sleep behaviour problem. Preventive interventions may help families and improve services. There is evidence that ‘limit-setting’ parenting, which is common in western cultures, supports the development of settled infant night-time behaviour. However, a recent review has challenged this and argued that this form of parenting risks distressing infants. This study describes limit-setting parenting as practiced in London, compares it with ‘infant-cued’ parenting and measures the associated infant distress.

Methods

Longitudinal infrared video, diary and questionnaire observations comparing a General-Community (n=101) group and subgroups with a Bed-Sharing (n=19) group on measures of infant and parenting behaviours at night.

Findings

General-Community parents took longer to detect and respond to infant waking and signalling, and to begin feeding, compared with the highly infant-cued care provided by Bed-Sharing parents. The average latency in General-Community parents’ responding to infant night-time waking was 3.5 min, during which infants fuss/cried for around 1 min. Compared with Bed-Sharing parenting, General-Community parenting was associated with increased infant distress of around 30 min/night at two weeks, reducing to 12 min/night by three months of age. However, differences in infant distress between General-Community subgroups adopting limit-setting versus infant-cued parenting were not large or statistically significant at any age. The figures provide descriptive evidence about limit-setting parenting which may counter some doubts about this form of parenting and help parents and professionals to make choices.

Goodness of fit between prenatal maternal sleep and infant sleep: Associations with maternal depression and attachment security

The current study prospectively examined the ways in which goodness of fit between maternal and infant sleep contributes to maternal depressive symptoms and the mother-child relationship across the first years of life. In a sample of 173 mother-child dyads, maternal prenatal sleep, infant sleep, maternal depressive symptoms, and mother-child attachment security were assessed via self-report, actigraphy, and observational measures. Results suggested that a poor fit between mothers' prenatal sleep and infants' sleep at 8 months (measured by sleep diary and actigraphy) was associated with maternal depressive symptoms at 15 months. Additionally, maternal depression mediated the association between the interplay of mother and infant sleep (measured by sleep diary) and mother-child attachment security at 30 months. Findings emphasize the importance of the match between mother and infant sleep on maternal wellbeing and mother-child relationships and highlight the role of mothers' perceptions of infant sleep.

Infant sleep-wake behaviors at two weeks, three and six months

Although infant sleep-wake behavior presents several developmental changes during the first six months, literature lacks on reference values and few studies have explored the role of individual change and stability on infant sleep-wake behavior during the first six months. This study aimed (1) to describe infant sleep-wake behaviors during the 24-h period, day and night, at two weeks, three, and six months, (2) and to explore developmental changes and the role of individual change and stability on infant sleep-wake behaviors from two weeks to six months. Ninety-four primiparous mothers completed measures on infant sleep-wake behaviors at two weeks, three and six months. Significant developmental changes were found on infant sleep-wake behaviors from two weeks to six months. Two-week-old infants sleep 13.3h, spend 8.7h awake, awake 6.1 times, have 0.4h of latency to sleep, and 3.2h of longest sleep period. Three-month-old infants sleep 13.0h, spend 9.2h awake, awake 5.5 times, have 0.4h of latency to sleep, and 5.2h of longest sleep period. Six-month-old infants sleep 12.2h, spend 10.0h awake, awake 5.2 times, have 0.4h of latency to sleep, and 5.6h of longest sleep period. Significant individual change and stability were also found on infant sleep-wake behaviors from two weeks to six months. Despite significant developmental and individual changes, individual stability explains a significant amount of the variance on infant sleep-wake behaviors over the first six months of life.

Postpartum Maternal Sleep, Maternal Depressive Symptoms and Self-Perceived Mother-Infant Emotional Relationship

This study examined the links between maternal sleep, maternal depressive symptoms, and mothers' perceptions of their emotional relationship with their infant in a self-recruited sample of mothers. Eighty mothers of infants 3-18 months old completed sleep diaries for 5 consecutive nights, and questionnaires assessing sleep (Insomnia Severity Index [ISI]), depressive symptom severity (Edinburgh Postnatal Depression Scale [EPDS]), and perceived mother-infant relationship (Postpartum Bonding Questionnaire [PBQ] and Maternal Postnatal Attachment Questionnaire [MPAQ]). Significant correlations, controlling for depression severity, were found between more disturbed maternal sleep and more negative maternal perceptions of the mother-infant relationship. Regression analyses revealed that EPDS showed the strongest association with PBQ, whereas ISI demonstrated the strongest association with MPAQ. The present study highlights the importance of deepening and expanding our understanding of the negative implications of maternal sleep problems.

PARENTAL REGULATION OF INFANT SLEEP: ROUND-THE-CLOCK EFFORTS FOR SOCIAL SYNCHRONIZATION

The sleep-cycle development of infants is influenced by familial and sociocultural conditions, but there is a lack of knowledge on how parental regulation of infant sleep is related to the specific life situation of a family. This article describes a context-sensitive study of parental regulation of infant sleep that includes the whole 24-hr day, parents' intentions, and familial and sociocultural conditions. The results are based on a longitudinal qualitative study in Norway of 51 families. Parents were interviewed in the infants' first year of life and approximately 18 months later. An interpretive analysis in four steps was conducted, informed by cultural psychological perspectives on development. The parents were found to perform five types of regulatory actions: facilitating sleep, letting sleep, letting be awake, keeping awake, and waking. These actions were performed continuously throughout the 24-hr day, each to different extents and at different hours in individual families, forming a regulation cycle. We describe patterns and variations in regulation cycles, changes over time as increased social synchronization, and how the regulation cycle is embedded in familial and sociocultural conditions. Finally, implications for clinical practice are discussed.

Infant sleep and feeding patterns are associated with maternal sleep, stress, and depressed mood in women with a history of major depressive disorder (MDD)

Our goal was to examine associations of infant sleep and feeding patterns with maternal sleep and mood among women at risk for postpartum depression. Participants were 30 women (age ± SD = 28.3 ± 5.1 years) with a history of MDD (but not in a mood episode at enrollment) who completed daily sleep diaries, wore wrist actigraphs to estimate sleep, and had their mood assessed with the Hamilton Depression Rating Scale (HAM-D-17) during four separate weeks of the perinatal period (33 weeks pregnancy and weeks 2, 6, and 16 postpartum). They logged their infants' sleep and feeding behaviors daily and reported postnatal stress on the Childcare Stress Inventory (CSI) at week 16. Mothers' actigraphically estimated sleep showed associations with infant sleep and feeding patterns only at postpartum week 2. Shorter duration of the longest infant-sleep bout was associated with shorter maternal sleep duration (p = .02) and lower sleep efficiency (p = .04), and maternal sleep efficiency was negatively associated with the number of infant-sleep bouts (p = .008) and duration of infant feeding (p = .008). Neither infant sleep nor feeding was associated with maternal sleep at 6 or 16 weeks, but more disturbed infant sleep and more frequent feeding at 6 weeks were associated with higher HAM-D scores at 6 and 16 weeks and higher CSI scores. Sleep in the mother-infant dyad is most tightly linked in the early postpartum weeks, but mothers continue to experience disturbed sleep and infant sleep and feeding behaviors continue to be associated with mothers' depressive symptoms and stress ratings as long as 16 weeks postpartum. These data imply that interventions designed to improve maternal sleep and postpartum mood should include both mothers and infants because improving infant sleep alone is not likely to improve maternal sleep, and poor infant sleep is linked to postpartum depression and stress.

Viii. Attachment and sleep among toddlers: disentangling attachment security and dependency

Many scholars have proposed that parent-child attachment security should favor child sleep. Research has yet, however, to provide convincing support for this hypothesis. The current study used objective measures of sleep and attachment to assess the longitudinal links between mother-child attachment security and subsequent sleep, controlling for child dependency. Sixty-two middle-class families (30 girls) were met twice, when children were 15 months (Wave 1; W1) and 2 years of age (Wave 2; W2). At W1, mother-child attachment was assessed with the observer version of the Attachment Q-Sort. At W2, children wore an actigraph monitor for 72 hr. Results indicated that children more securely attached to their mothers subsequently slept more at night and had higher sleep efficiency, and these predictions were not confounded by child dependency. These findings suggest a unique role for secure attachment relationships in the development of young children's sleep regulation, while addressing methodological issues that have long precluded consensus in this literature.

Daily dynamics in sleep and behavior of young African-American children: A convoluted dyad?!

Prior research has provided evidence that in children sleep and behavior are related. We aimed to determine the association between naturalistic daily variations in sleep and behavioral functioning. African American children, 5.4±1.7years old, living on the south side of Chicago participated in a repeated measures study to assess this sleep-behavior link. Data was obtained from three separate two-week periods of 24-hour actigraphy and the parental version of the Behavioral Assessment System for Children. Canonical correlations analyses were applied to investigate the relation between individual changes in sleep and behavior. After 1-month, weekday average sleep duration primarily related to internalizing behaviors, while within-child variability of sleep related to behavioral changes which may involve internalizing and externalizing symptoms. Week-weekend differences in sleep associated with maladaptive social skills. Over a 6-week period, sleep onset latency and sleep offset latency related to behavioral symptoms and maladaptive skills. Over a period of 3-months, sleep associated with symptomatic behaviors while the adverse impact of within-child variability of sleep attenuated. Alternatively, the week-weekend differences in bedtime, wake-up time, wake after sleep onset and sleep onset latency in particular related to internalizing and externalizing behavior problems. Findings showed that poor sleep related to dysfunctional behaviors. While maladaptive at the beginning, they may develop into symptomatic behaviors with potentially internalizing characteristics. As time goes on, individual changes in sleep onset and offset might be important clinical markers of a chronic 'social dysregulation'. Continued sufficient and regular sleep may improve daytime and nighttime behavioral regulation in early childhood.

Assessment of nocturnal sleep architecture by actigraphy and one-channel electroencephalography in early infancy

OBJECTIVE

To elucidate characteristic sleep architecture of different nocturnal sleep patterns in early infancy.

METHODS

Participants were 27 infants at the same conceptional age of 3-4months. Nocturnal sleep of these infants was monitored at home by simultaneously using actigraphy and a one-channel portable EEG device. According to the infants' activity for 6h from sleep onset, each night's sleep pattern was classified into three categories: sleeping through the night (STN), sleeping with weak signals (crying/fuss episodes <10min or fed), and sleeping with strong signals (crying/fuss episodes≧10min). Associations of sleep patterns with sleep variables (percentage of time in sleep stages, pattern of slow-wave sleep (SWS) recurrence, etc.) were investigated.

RESULTS

Analysis was conducted in 95 nights. STN pattern (n=36) was characterized by suppressed body movements while EEG represented a state of wakefulness. Weak signal pattern (n=27) tended to indicate rich and regular distributions of SWS across the night. Strong signal pattern (n=32) was characterized by reduced sleep time, although the amount of SWS was not reduced to that degree. Exclusively breastfed infants accounted for 78% of weak signal patterns, whereas formula-feeding infants, 67% of STN patterns. In several nights with STN or strong signal pattern, SWS did not occur in >50% of the sleep cycles. Multiple regression analysis showed that exclusive breastfeeding may increase the proportion of SWS in non-REM sleep.

CONCLUSIONS

Each nocturnal sleep pattern was associated with some sleep architecture, part of which would be attributed to infant's feeding methods.

Sleep Habits and Sleep Problems in Healthy Preschoolers

OBJECTIVES

To describe the sleep patterns and problems in children aged between 12 and 36 mo of age.

METHODS

This cross sectional survey was collected over a span of 1 y in Advanced Pediatric Centre, PGIMER, Chandigarh and crèches of Chandigarh. Children in the age group of 12 to 36 mo were included in study. Children with chronic illness, developmental delay, seizure disorder and lack of consent were excluded. A total of 368 children were enrolled. Main outcome measures were sleep duration over 1 to 3 y of life; sleep behavior at onset, during and waking of sleep and parent reported sleep problems and their predictors.

RESULTS

The average duration of sleep was 12.5 h (S.D = 1.9). The mean total sleep duration and mean day time sleep duration decreased, while mean night time sleep increased as the age advanced from 12 to 36 mo. Following were the frequency of sleep habits seen in the index study; bed time routine was seen only in 68(18.5 %), a regular bed time ritual was seen in 281(76.4 %), 329(89.4 %) children frequently required 0-20 min time to fall asleep, 11(3 %) parents used sleep inducing drugs. Night waking (1 to 3 times a night) was seen in 297(80.7 %) and its frequency declined with age. Parent reported sleep problems were seen in 12.8 % (47/368). Lack of co-sleeping and night waking were considered as strongest predictors of parent reported sleep problems.

CONCLUSIONS

Toddlers' sleep duration, night waking behavior, and day time naps decrease as the age progress while night time sleep duration increases with age. Lack of co-sleeping and night waking are considered as strongest predictors of parent reported sleep problems.

Infant sleep and night feeding patterns during later infancy: association with breastfeeding frequency, daytime complementary food intake, and infant weight

Infant sleep is a common concern for new parents. Although many expect a newborn infant to wake frequently, encouraging a baby to sleep through the night by a few months of age is seen as both a developmental aim and a parenting success. Many new mothers believe that their infants' diet is related to their sleep; formula milk or increased levels of solid food are often given in an attempt to promote sleep. However, the impact of these in later infancy is not understood. In the current study 715 mothers with an infant 6-12 months of age reported their infants' typical night wakings and night feeds alongside any breastfeeding and frequency of solid meals. Of infants in this age range, 78.6% still regularly woke at least once a night, with 61.4% receiving one or more milk feeds. Both night wakings and night feeds decreased with age. No difference in night wakings or night feeds was found between mothers who were currently breastfeeding or formula feeding. However, infants who received more milk or solid feeds during the day were less likely to feed at night but not less likely to wake. The findings have important implications for health professionals who support new mothers with infant sleep and diet in the first year. Increasing infant calories during the day may therefore reduce the likelihood of night feeding but will not reduce the need for parents to attend to the infant in the night. Breastfeeding has no impact on infant sleep in the second 6 months postpartum.

Associations between infant temperament, maternal stress, and infants' sleep across the first year of life

Effects of temperament and maternal stress on infant sleep behaviors were explored longitudinally. Negative temperament was associated with sleep problems, and with longer sleep latency and night wakefulness, whereas maternal stress was associated with day sleep duration, suggesting infant and maternal characteristics affect sleep differentially.

Sleep and breathing in premature infants at 6 months post-natal age

Background

Poor sleep contributes to the developmental problems seen in preterm infants. We evaluated sleep problems in preterm infants 6 months of post-gestational age using the subjective Brief Infant Sleep Questionnaire (BISQ) and objective sleep tests. We also compared the sleep of premature infants with that of full-term infants.

Methods

The study included 68 6-month-old full-term healthy infants and 191 premature infants born at <37 weeks gestation. All parents completed the BISQ-Chinese version and sleep diaries. At the same time, all premature infants were submitted to one night of polysomnography (PSG) in the sleep laboratory and also were set up with an actigraph kept for 7 days. Statistical analyses were performed using correlation coefficients and the t-test with SPSS version 18 to compare questionnaire responses with other subjective and objective measures of sleep.

Results

The sleep problems indicated in the subjective questionnaire for the premature infants, particularly: “the nocturnal sleep duration, number of night awakenings, daytime sleep duration, duration of time with mouth breathing, and loud-noisy breathing” had significant correlations with sleep diaries, actigraphy and PSG results. The BISQ showed that duration of infant’s sleeping on one side, nocturnal sleep duration, being held to fall asleep, number of nighttime awakenings, daytime sleep duration, subjective consideration of sleep problems, loud-noisy breathing, and duration spent crying during the night were significantly different between the premature infants and the term infants. PSG confirmed the presence of a very high percentage (80.6%) of premature infants with AHI > 1 event/hour as indicated by the questionnaire.

Conclusion

Premature infants have more sleep problems than full-term infants, including the known risk of abnormal breathing during sleep, which has been well demonstrated already with the BISQ-Chinese (CBISQ).

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-014-0303-6) contains supplementary material, which is available to authorized users.

Translating research-based knowledge about infant sleep into practice

PURPOSE

Review infant sleep research with a focus on understanding the elements related to infant safety and infant and maternal well-being during nighttime care.

DATA SOURCES

This review summarizes current research and addresses the controversies and conflicting outcomes reported in infant nighttime care. This review addresses current literature on infant sleep patterns, as well as factors that influence infant sleep and are consequences of different care routines. Conversation points are provided to help nurse practitioners (NPs) address safety and practice concerns.

CONCLUSIONS

Shared information can help parents provide a safe and healthy environment for infants and help to facilitate communication ties between the healthcare providers and the families.

IMPLICATIONS FOR PRACTICE

NPs need to help parents understand infant sleep patterns norms, what is current knowledge about infant nightwakings and parental presence, as well as about approaches to altering infant sleep patterns. Integrating this knowledge with parent preferences that are influenced by cultural practices and individual differences is crucial in helping parents develop a strong sense of competence and comfort with their choices and behaviors.

Are baby hammocks safe for sleeping babies? A randomised controlled trial

AIM

Two reports of infants found dead after sleeping in baby hammocks have raised international concern about the safety of infant hammocks. We therefore tested whether hammock sleep affected oxygenation in infants, when they were at an age of high risk of sudden, unexpected infant death.

METHODS

Healthy, full-term 4- to 8-week-old infants were randomised to sleep either in a commercially available hammock (n = 14) or a standard bassinet (n = 9), and sleep state, oxygen desaturation (a fall in peripheral haemoglobin oxygen saturation (SpO2 ) ≥ 4%, for ≥ 4 sec from baseline to nadir), apnoea and hypopnoea, and mean SpO2 were analysed.

RESULTS

There was no significant difference in mean SpO2 (both 98.5%) or rate of oxygen desaturation events between the hammock and the bassinet cot (mean ± SD, 24 ± 20 vs. 28 ± 23 events per hour), but infants slept less in the hammock (59 ± 31 vs. 81 ± 34 min, p < 0.02).

CONCLUSION

When correctly used, the hammock sleep position did not compromise the upper airway of sleeping infants. The significance of shorter duration of sleep in the hammocks is unclear. These findings should not be applied to all baby hammocks, nor to older babies, particularly once the infant can roll. Given that it is not possible to predict when an infant will be able to roll, we strongly recommend that hammocks should not be used for unsupervised sleep.

Investigating the Convergence between Actigraphy, Maternal Sleep Diaries, and the Child Behavior Checklist as Measures of Sleep in Toddlers

The current study examined associations among actigraphy, maternal sleep diaries, and the parent-completed child behavior checklist (CBCL) sleep items. These items are often used as a sleep measure despite their unclear validity with young children. Eighty middle class families (39 girls) drawn from a community sample participated. Children (M = 25.34 months, SD = 1.04) wore an actigraph monitor (Mini-Mitter(®) Actiwatch Actigraph, Respironics) for a 72-h period, and mothers completed a sleep diary during the same period. Eighty-nine percent of the mothers and 75% of the fathers also filled out the CBCL (1.5-5). Mother and father CBCL scores were highly correlated. Overall, good correspondence was found between the CBCL filled out by mothers and sleep efficiency and duration derived from maternal sleep diaries (r between -0.39 and -0.25, p ≤ 0.05). Good correspondence was also found between the CBCL filled out by fathers and sleep efficiency as derived from maternal sleep diaries (r between -0.39 and -0.24, p ≤ 0.05), but not with sleep duration (all results were non-significant). Very few correlations between actigraphy and the CLBL scores reached statistical significance. The Bland and Altman method revealed that sleep diaries and actigraphy showed poor agreement with one another when assessing sleep duration and sleep efficiency. However, diary- and actigraphy-derived sleep durations were significantly correlated. Consistent with findings among older groups of children, this study suggests that the CBCL sleep items, sleep diaries, and actigraphy tap into quite different aspects of sleep among toddlers. The choice of which measures to use should be based on the exact aspects of sleep that one aims to assess. Overall, despite its frequent use, the composite sleep score of the CBCL shows poor links to objective measures of sleep duration and sleep efficiency.

Randomized Trial of Promoting First Relationships: Effects on Maltreated Toddlers' Separation Distress and Sleep Regulation after Reunification

This study investigates the impact of an attachment focused intervention, Promoting First Relationships (PFR), on sleep problems among toddlers in child welfare recently reunified with their birth parent. Recently reunified parent-toddler dyads (n = 43) were drawn from a larger random control trial. Toddlers (11-36 months) and their parents were assessed in two-hour research home visits at enrollment (baseline), and a 6-month post-intervention follow-up. Measures included parental report of sleep problems and research visitor observation of separation distress (using the Toddler Attachment Sort-45). The PFR intervention predicted fewer sleep problems, adjusting for a baseline measure of sleep problems and other covariates. A path model showed evidence of an indirect effect of PFR on sleep problems through declines in separation distress. An attachment focused intervention like PFR that reduces infant separation distress can lead to reductions in sleep problems.

Infant sleep problems: a qualitative analysis of first-time mothers' coping experience

OBJECTIVE

to describe the aspects of infant sleep perceived as problematic by first-time Taiwanese mothers and to discover how mothers cope in response to infant sleep concerns.

DESIGN

a qualitative approach was used for data collection.

SETTING

in-depth interviews were conducted and audio-taped at mothers' homes.

PARTICIPANTS

12 first-time mothers within three months post partum.

MEASUREMENT AND FINDINGS

content analysis was performed to identify patterns, similarities, and differences in the individual and collective interview data. The major themes describing maternal coping experiences were 'self-help' and 'seek-help.' Self-help coping efforts included reception and acceptance of suggestions as well as changing behaviour to allow mothers to feel capable of adapting to infant sleep patterns or problems. Seek-help was a later stage of coping for mothers when they actively utilised formal and informal sources of help to identify and manage infant sleep problems. The majority of mothers sought informal help sources from family members, friends, or online information. Mothers who suspected their infant of suffering from sleep problems either delayed seeking medical advice or did not actively consult a health care provider.

CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

nurses and health care providers who work in antenatal, postnatal, and paediatric clinics should actively educate and provide information about infant sleep patterns and sleep management options to first-time mothers and discuss maternal coping strategies.

Cross syndrome comparison of sleep problems in children with Down syndrome and Williams syndrome

Based on previous findings of frequent sleep problems in children with Down syndrome (DS) and Williams syndrome (WS), the present study aimed to expand our knowledge by using parent report and actigraphy to define sleep problems more precisely in these groups. Twenty-two school-aged children with DS, 24 with WS and 52 typically developing (TD) children took part in the study. Each child wore an actiwatch for a minimum of four nights and parents completed the Children's Sleep Habits Questionnaire (CSHQ). Sleep problems were common in both developmental disorders. Children with DS had the greatest sleep disruption, with frequent and longer night wakings as well as restlessness. Parents reported symptoms of sleep-disordered breathing and a range of other problems including grinding teeth, bedtime resistance and sleep anxiety. Children with WS had problems initiating sleep and parents also reported bed-wetting and body pain. Despite these problems, the mean actual sleep time, as measured by actigraphy, did not differ between the three groups. CSHQ reports were in agreement with actigraphy for children's sleep duration, but this was not the case for sleep latency, restlessness and the night wakings variables. Sleep problems in DS and WS are common and appear to be syndrome-specific. Due to the inaccuracy of parent report, it is recommended that children at risk undergo objective measures of sleep assessment.

Relationship between duration of crying/fussy behavior and actigraphic sleep measures in early infancy

OBJECTIVE

The objective of the study is to understand the relationship between sleep development and crying episodes during early infancy more accurately by longitudinal and objective sleep evaluations.

DESIGN

The study is designed as a prospective longitudinal study of infants in the first 4 months of life.

METHODS

This study included 31 healthy term infants. At approximately 4- to 6-week intervals, when the infants were aged 4-6 weeks, 8-10 weeks, and 14-16 weeks, their mothers recorded the duration of crying/fussy behavior of infants in a timetable and attached an actigraph to the infants for 3 days. The relationship between 24-h crying/fussy behavior duration and actigraphic sleep measures was examined from both a cross-sectional (age group) and longitudinal (within-infants) perspective. Interactions with diverse covariates were studied by multiple regression analysis.

RESULTS

A significant correlation was found between 24-h crying/fussy behavior duration and proportion of active sleep in infants at 14-16 weeks and in within-infant relationships. Among potential covariates, gestational age and co-sleeping had a significant impact on proportion of active sleep. Results of multiple regression analysis showed that gestational age and co-sleeping were positively associated with proportion of active sleep, whereas 24-h crying/behavior duration was not associated with proportion of active sleep.

CONCLUSIONS

Subsiding of early crying and decreasing of proportion of active sleep are parallel phenomena in some infants. However, this association was thought to be attributable to the influence of covariates, including co-sleeping or gestational age. The underlying mechanisms regulating these developmental processes might overlap with one another, as covariates that affect one process could affect the other.

Effect of current breastfeeding on sleep patterns in infants from Asia-Pacific region

AIM

  The aim of this study was to assess the relationship between breastfeeding and sleep patterns in infants from Asia-Pacific region.

METHODS

  Parents of 10 321 infants (0-11 months) from Australia, China, Hong Kong, India, Indonesia, Korea, Japan, Malaysia, New Zealand, the Philippines, Singapore, Taiwan, Thailand and Vietnam completed an expanded version of the Brief Infant Sleep Questionnaire.

RESULTS

  Overall, 4714 (45.72%) were currently being breastfed; 61.3% of those between 0 and 5 months and 36.6% of those between 6 and 11 months. Currently breastfed infants, when compared with not currently breastfed infants, had a significant increase in the number and duration of night-time wakings and less consolidated sleep. Interestingly, currently breastfed infants less than 6 months also showed longer duration of daytime sleep and obtained more sleep overall. Of note, of those who were currently breastfed, those infants who were nursed back to sleep during night, woke up more often at night (2.41 vs. 1.67 times) and had shorter continuous night-time sleep period (5.58 vs. 6.88 h; P < 0.001). There was no significant difference between breastfeeding and non-breastfeeding infants in the number of night wakings, when the nursing to sleep variable was controlled for in the analysis of variance.

CONCLUSION

  Breastfeeding is associated with reduced sleep consolidation in infants. This relationship, however, may be moderated by parenting practices of nursing to sleep and back to sleep during the night. Thus, parents of infants with night waking problems should be encouraged to limit the association between nursing and falling to sleep, to improve sleep while maintaining breastfeeding.

Postpartum maternal sleep and mothers’ perceptions of their attachment relationship with the infant among women with a history of depression during pregnancy

This study assessed the links between maternal sleep and mothers’ perceptions of their attachment relationship with their infant among women at risk for postpartum depression by virtue of having been depressed during pregnancy. Sixty-two mothers completed sleep diaries and questionnaires at 3 and 6 months postpartum. Regression analyses, controlling for depression severity and infant temperament, revealed significant prospective correlation between maternal shorter total sleep time at 3 months and lower scores on a mother–infant attachment questionnaire at 6 months. At 6 months, the longer time mothers were awake tending to their infants the lower were their attachment scores. The findings suggest that improving sleep of mothers who suffered from prenatal depression may have a positive effect on mothers’ self-reported relationship with their infants.

Genetic and environmental contributions to stability and change of sleep problems in toddlerhood

OBJECTIVE

To examine genetic and environmental contributions to stability and change in sleep problems (SP) in early childhood.

METHODS

The sample comprised over 300 twin pairs assessed at ages 2 and 3 years. Parents rated SP on the Sleep Problems subscale of the Child Behavior Checklist for ages 1.5-5 years.

RESULTS

Longitudinal quantitative genetic analyses indicated that SP were genetically influenced at both ages. The stability of SP from ages 2 to 3 years was largely due to genetic factors common to both ages. Nonshared environmental influences displayed modest continuity across age. New genetic and nonshared environmental factors emerged at age 3 years.

CONCLUSIONS

Genetic factors contribute to the stability in SP, whereas change is due to both genetic and nonshared environmental influences. Early interventions on SP and individualized treatments based on children's unique environmental experiences may be fruitful.

Baby Business: a randomised controlled trial of a universal parenting program that aims to prevent early infant sleep and cry problems and associated parental depression

BACKGROUND

Infant crying and sleep problems (e.g. frequent night waking, difficulties settling to sleep) each affect up to 30% of infants and often co-exist. They are costly to manage and associated with adverse outcomes including postnatal depression symptoms, early weaning from breast milk, and later child behaviour problems. Preventing such problems could improve these adverse outcomes and reduce costs to families and the health care system. Anticipatory guidance-i.e. providing parents with information about normal infant sleep and cry patterns, ways to encourage self-settling in infants, and ways to develop feeding and settling routines before the onset of problems-could prevent such problems. This paper outlines the protocol for our study which aims to test an anticipatory guidance approach.

METHODS/DESIGN

750 families from four Local Government Areas in Melbourne, Australia have been randomised to receive the Baby Business program (intervention group) or usual care (control group) offered by health services. The Baby Business program provides parents with information about infant sleep and crying via a DVD and booklet (mailed soon after birth), telephone consultation (at infant age 6-8 weeks) and parent group session (at infant age 12 weeks). All English speaking parents of healthy newborn infants born at > 32 weeks gestation and referred by their maternal and child health nurse at their first post partum home visit (day 7-10 postpartum), are eligible. The primary outcome is parent report of infant night time sleep as a problem at four months of age and secondary outcomes include parent report of infant daytime sleep or crying as a problem, mean duration of infant sleep and crying/24 hours, parental depression symptoms, parent sleep quality and quantity and health service use. Data will be collected at two weeks (baseline), four months and six months of age. An economic evaluation using a cost-consequences approach will, from a societal perspective, compare costs and health outcomes between the intervention and control groups.

DISCUSSION

To our knowledge this is the first randomised controlled trial of a program which aims to prevent both infant sleeping and crying problems and associated postnatal depression symptoms. If effective, it could offer an important public health prevention approach to these common, distressing problems.

Prevalence, patterns, and persistence of sleep problems in the first 3 years of life

OBJECTIVE

Examine the prevalence, patterns, and persistence of parent-reported sleep problems during the first 3 years of life.

METHODS

Three hundred fifty-nine mother/child pairs participated in a prospective birth cohort study. Sleep questionnaires were administered to mothers when children were 6, 12, 24, and 36 months old. Sleep variables included parent response to a nonspecific query about the presence/absence of a sleep problem and 8 specific sleep outcome domains: sleep onset latency, sleep maintenance, 24-hour sleep duration, daytime sleep/naps, sleep location, restlessness/vocalization, nightmares/night terrors, and snoring.

RESULTS

Prevalence of a parent-reported sleep problem was 10% at all assessment intervals. Night wakings and shorter sleep duration were associated with a parent-reported sleep problem during infancy and early toddlerhood (6-24 months), whereas nightmares and restless sleep emerged as associations with report of a sleep problem in later developmental periods (24-36 months). Prolonged sleep latency was associated with parent report of a sleep problem throughout the study period. In contrast, napping, sleep location, and snoring were not associated with parent-reported sleep problems. Twenty-one percent of children with sleep problems in infancy (compared with 6% of those without) had sleep problems in the third year of life.

CONCLUSIONS

Ten percent of children are reported to have a sleep problem at any given point during early childhood, and these problems persist in a significant minority of children throughout early development. Parent response to a single-item nonspecific sleep query may overlook relevant sleep behaviors and symptoms associated with clinical morbidity.

Sleeping through the night: the consolidation of self-regulated sleep across the first year of life

OBJECTIVE

To investigate the consolidation of infants' self-regulated nocturnal sleep over the first year, to determine when infants first sleep through the night from 24:00 to 05:00 hours (criterion 1), for 8 hours (criterion 2), or between 22:00 and 06:00 hours (the family-congruent criterion 3).

METHODS

This was a prospective longitudinal study with repeated measures. Parents of 75 typically developing infants completed sleep diaries for 6 days each month for 12 months. Accuracy of parent reports were assessed by using videosomnography.

RESULTS

The largest mean increase (504 minutes) in self-regulated sleep length occurred from 1 to 4 months. The survival function decreased most rapidly (indicating greatest probability of meeting criteria) for criterion 1 at 2 months, criterion 2 at 3 months, and criterion 3 at 4 months. A 50% probability of meeting criteria 1 and 2 occurred at 3 months and at 5 months for criterion 3. The hazard function identified 2 months (criteria 1 and 2) and 3 months (criterion 3) as the most likely ages for sleeping through the night. At 12 months, 11 infants did not meet criteria 1 or 2, whereas 21 failed to meet criterion 3.

CONCLUSIONS

The most rapid consolidation in infant sleep regulation occurs in the first 4 months. Most infants are sleeping through the night at 2 and 3 months, regardless of the criterion used. The most developmentally and socially valid criterion for sleeping through is from 22:00 to 0:600 hours. At 5 months, more than half of infants are sleeping concurrently with their parents.

Sleep of excessively crying infants: a 24-Hour Ambulatory Sleep Polygraphy study

OBJECTIVE

Parents' reports suggest that excessively crying or colicky infants sleep less compared with control subjects. The aim of this study was to determine the sleep-wake structure of excessively crying infants throughout a 24-hour cycle.

METHODS

A 24-hour sleep polygraphy study was conducted at home for 24 excessively crying infants and 23 control subjects at the age of 6 weeks. In addition, parental diaries were kept for 4 days.

RESULTS

In sleep polygraphy recordings, no major differences between study groups were observed in either the duration or the structure of the 24-hour sleep. In the diaries, the parents overestimated the amount of sleep in both study groups. The parents of the control infants overestimated the amount of sleep more than the parents of excessively crying infants (69.8 minutes [standard deviation: 79.3] compared with 27.1 minutes [standard deviation: 65.4], respectively). In excessively crying infants, the proportion of rapid eye movement sleep was higher during the 3-hour period from the beginning of the first long sleep in the evening and lower during the preceding 3-hour period compared with the control group.

CONCLUSIONS

The results of this study suggest that diary-based studies are prone to be biased as the parents of the control infants are more likely to overestimate the amount of infant's sleep and, therefore, report more sleep than the parents of the crying infants. Although no differences in the total amount of sleep or proportions of sleep stages were observed, excessively crying infants may be characterized by a disturbance that affects rapid eye movement and non-rapid eye movement sleep stage proportion during evening hours.