Sleep in the first year of life

The Architecture of Early Childhood Sleep Over the First Two Years

INTRODUCTION

The architecture and function of sleep during infancy and early childhood has not been fully described in the scientific literature. The impact of early sleep disruption on cognitive and physical development is also under-studied. The aim of this review was to investigate early childhood sleep development over the first two years and its association with neurodevelopment.

METHODS

This review was conducted according to the 2009 PRISMA guidelines. Four databases (OVID Medline, Pubmed, CINAHL, and Web of Science) were searched according to predefined search terms.

RESULTS

Ninety-three studies with approximately 90,000 subjects from demographically diverse backgrounds were included in this review. Sleep is the predominant state at birth. There is an increase in NREM and a decrease in REM sleep during the first two years. Changes in sleep architecture occur in tandem with development. There are more studies exploring sleep and early infancy compared to mid and late infancy and early childhood.

DISCUSSION

Sleep is critical for memory, learning, and socio-emotional development. Future longitudinal studies in infants and young children should focus on sleep architecture at each month of life to establish the emergence of key characteristics, especially from 7-24 months of age, during periods of rapid neurodevelopmental progress.

Sleep disordered breathing (SDB) in neonates and implications for its long-term impact

Sleep-disordered breathing (SDB) is a significant cause of morbidity in neonates and young infants. SDB occurs more commonly in preterm infants and in neonates with underlying syndromes. Recent evidence shows that infants with obstructive sleep apnoea (OSA) or SDB have greater health care resource utilization, including longer hospital stay. Management of SDB includes non-invasive ventilation or surgical interventions tailored to the patient. Screening high risk newborns should allow for early diagnosis and timely therapeutic intervention for this population. However, the thresholds for diagnosing SDB and for guiding and implementing treatment in neonates remain unclear. A collective effort is required to standardize the practice worldwide. This article will discuss neonatal sleep physiology and characteristics of neonatal sleep, with an emphasis on the epidemiology and diagnosis of SDB in neonates and its implications for long term outcomes.

Post-Traumatic Sleep-Wake Disorders

All living organisms that face a traumatic life event are susceptible to sleep-wake disturbances. Stress, which can result in trauma, evokes a high level of physiological arousal associated with sympathetic nervous system activation, during both sleep and wakefulness. Heredity, sex hormones, early losses, developmental factors and intra- and interpersonal conflicts, contribute to the level of baseline physiological arousal, producing either subclinical, clinical or complex clinical traits, acutely and at any time after exposure to a traumatic event. The risk of acute sleep-wake disturbances becoming disorders and syndromes depends on the type of traumatic event and all of the aforementioned factors. Taken together, with consideration for behavioural and environmental heterogeneity, in research, will aid identification and understanding of susceptibility factors in long-term sleep and wakefulness pathology after exposure to traumatic events.

Overnight Polysomnographic Characteristics and Oxygen Saturation of Healthy Infants, 1 to 18 Months of Age, Born and Residing At High Altitude (2,640 Meters)

BACKGROUND

Approximately 8% of the world population resides above 1,600 m, with about 10 million people living above 2,500 m in Colombia. However, reference values for polysomnography (PSG) and oxygen saturation (Spo2) of children < 2 years old residing at high altitude are currently unavailable.

METHODS

Healthy infants aged 1 to 18 months born and residing at high altitude (Bogotá: 2,640 m) underwent overnight PSG. Four age groups were defined: group 1, < 45 days; group 2, 3 to 4 months; group 3, 6 to 7 months; and group 4, 10 to 18 months. Of 122 children enrolled, 50 had three consecutive PSG tests and were analyzed as a longitudinal subcohort.

RESULTS

A total of 281 PSG tests were performed in 122 infants (56% girls): group 1, 106 PSG tests; group 2, 89 PSG tests; group 3, 61 PSG tests; and group 4, 25 PSG tests. Active sleep diminished and quiet sleep increased with maturation. Apnea-hypopnea indexes (total, central, and obstructive) were highest in group 1 (21.4, 12.4, and 6.8/h total sleep time, respectively) and diminished with age (P < .001). Mean Spo2 during waking and sleep increased with age (P < .001). Nadir Spo2 values during respiratory events were lower in younger infants. Longitudinal assessments of 50 infants confirmed the temporal trends described for the cross-sectional dataset.

CONCLUSIONS

Healthy infants (≤ 18 months old) born and residing at high altitude show preserved sleep architecture but higher apnea-hypopnea indexes and more prominent desaturation with respiratory events than do those living at low altitude. The current study findings can be used as reference values for infants at high altitude.

Developmental changes in sleep and breathing across infancy and childhood

Sleep and breathing are physiological processes that begin in utero and undergo progressive change. While the major period of change for both sleep and breathing occurs during the months after birth, considered a period of vulnerability, more subtle changes continue to occur throughout childhood. The systems that control sleep and breathing develop separately, but sleep represents an activity state during which breathing and breathing control is significantly altered. Infants and young children may spend up to 12 hours a day sleeping; therefore, the effects of sleep on breathing are fundamental to understanding both processes in childhood. This review summarizes the current literature relevant to understanding the normal development of sleep and breathing across infancy and childhood.

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.

Analyzing temporal patterns of infant sleep and negative affective behavior: a comparison between different statistical models

OBJECTIVE

Variability in infant sleep and negative affective behavior (NAB) is a developmental phenomenon that has long been of interest to researchers and clinicians. However, analyses and delineation of such temporal patterns were often limited to basic statistical approaches, which may prevent adequate identification of meaningful variation within these patterns. Modern statistical procedures such as additive models may detect specific patterns of temporal variation in infant behavior more effectively.

METHOD

Hundred and twenty-one mothers were asked to record different behaviors of their 4-44 weeks old healthy infants by diaries for three days consecutively. Circadian patterns as well as individual trajectories and day-to-day variability of infant sleep and NAB were modeled with generalized linear models (GLMs) including a linear and quadratic polynomial for time, a GLM with a polynomial of the 8th order, a GLM with a harmonic function, a generalized linear mixed model (GLMM) with a polynomial of the 8th order, a generalized additive model, and a generalized additive mixed model (GAMM).

RESULTS

The semi-parametric model GAMM was found to fit the data of infant sleep better than any other parametric model used. GLMM with a polynomial of the 8th order and GAMM modeled temporal patterns of infant NAB equally well, although the GLMM exhibited a slightly better model fit while GAMM was easier to interpret. Besides the well-known evening clustering in infant NAB we found a significant second peak in NAB around midday that was not affected by the constant decline in the amounts of NAB across the 3-day study period.

CONCLUSION

Using advanced statistical procedures (GAMM and GLMM) even small variations and phenomena in infant behavior can be reliably detected. Future studies investigating variability and temporal patterns in infant variables may benefit from these statistical approaches.

Sleep and physical growth in infants during the first 6 months

The aim of this study was to explore the relationships between infant sleep patterns and infant physical growth (weight for length ratio) using both objective and subjective sleep measures. Ninety-six first-born, healthy 6-month-old infants and their parents participated in the study. Infant sleep was assessed by actigraphy for four consecutive nights and by the Brief Infant Sleep Questionnaire (BISQ). In addition, parents were asked to complete background and developmental questionnaires. Questions about feeding methods were included in the developmental questionnaire. Infants' weight and length were assessed during a standard checkup at the infant-care clinic when the infants were 6 months old. Significant correlations were found between infant sleep and growth after controlling for potential infant and family confounding factors. Actigraphic sleep percentage and reported sleep duration were correlated negatively with the weight-to-length ratio measures. Sex-related differences in the associations between sleep and physical growth were found. Breast feeding at night was correlated with a more fragmented sleep, but not with physical growth. These findings suggest that sleep is related significantly to physical growth as early as in the first months of life. The study supports increasing evidence from recent studies demonstrating a link between short sleep duration and weight gain and obesity in young children.

Epidemiological study of sleep characteristics in Chinese children 1-23 months of age

BACKGROUND

Sleep plays a critical role in normal development and the effects of culture upon sleep are especially important in young children. The purpose of the present paper was to determine the sleep times and the prevalence of sleep problems and co-sleeping in children from Shanghai.

METHODS

A cross-sectional design incorporating parental self-report was used to investigate the sleep-related habits of 1129 children, 1-23 months of age, randomly selected from the five districts of Shanghai, China.

RESULTS

The total sleep time (TST) of Chinese young children was less than that reported in Western populations, and the prevalence of sleep problems (65.97%) was higher than that for Western children. The sleep problems of children were significantly related to perinatal factors and certain behavior problems. The rate of bed sharing did not differ between boys and girls but significantly increased with age from 44.07% in 1-month-olds to 71.51% in 23-month-olds.

CONCLUSIONS

Sleep problems that cross cultures result from a variety of behavioral and health problems. Nevertheless, it is speculated that reduced TST in Chinese children may be related to factors unique to China, such as co-sleeping and child-rearing practices.

The use of actigraphy for assessment of the development of sleep/wake patterns in infants during the first 12 months of life

Maturation of sleep/wake patterns is one of the most important physiological developments during the first year of life. In this study, we aimed to compare the use of actigraphy and parental sleep diaries (SD) for recording the development of sleep/wake patterns longitudinally in term infants in their own home environments over the first 12 months of life. Twenty healthy term infants (7F/13M) were studied for 3 days each month in their own homes over the first 12 months of life. Sleep/wake patterns were recorded using both SD and actigraphy (AW) (AW64, Mini Mitter Co. Inc., Sunriver, OR, USA). The development of sleep and wake was analysed over 24 h, during the day (08:00-20:00 hours) and during the night (20:00-08:00 hours). A total of 186 studies had complete data sets for both analysis methods. Overall, there was no difference between methods of measurement for determination of the total percentage of sleep or wake over 24 h, or for the total percentage of sleep or wake during the day. However, at night, AW scored less time asleep (73.3 +/- 0.9%) and more time awake (26.7 +/- 0.9%) compared with the SD (80.7 +/- 1.04% and 19 +/- 1.0%, respectively, P < 0.001). Mean percentage sleep during the day decreased from 51% at 1 month to 28% at 12 months with the 1-month values being significantly higher than all other ages, while mean percentage sleep at night was only different between 1 month and 11 and 12 months. In conclusion actigraphy provides a useful tool for assessing the development infant sleep.

Desenvolvimento dos estados de sono na infância

Na perspectiva de descrever alguns aspectos da ontogênese e da organização dos estados de sono no primeiro ano de vida, revisou-se na literatura as alterações fisiológicas e comportamentais controladas pelas mudanças que ocorrem durante o sono nessa etapa desenvolvimental. Além disso, com fundamentação na teoria precursora do sono, expõe-se as etapas da diferenciação, a classificação e a organização temporal dos estados de sono, com vistas ao manejo favorável dos eventos ambientais, que afetam a organização do sono infantil.

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.

[Treatment of insomnia in children: pharmacological aspects]

In the last few years topics related to sleep in children have aroused increased interest. Most hypnotic drugs and sedatives used to treat adult insomnia are not recommended in children. Even so, 56% of pediatricians use medication to treat childhood sleep disorders. We review the different causes of insomnia in children from birth to school age. The various therapeutic options are discussed and the therapeutic methods that have been demonstrated to be most effective in the various types of insomnia. The most frequent hypnotic drugs used in insomnia treatment are benzodiazepines and non-benzodiazepine hypnotics such as imidazopyridine, pyrazolopyrimidine and cyclopyrrolone. Few studies have been published on the use of melatonin in insomnia although several reports suggest that is useful and relatively safe in the treatment of insomnia in school-aged children. In children with insomnia, pediatricians should first of all obtain information about the characteristics of insomnia and the environmental characteristics surrounding the child and his/her family. Once an organic cause has been ruled out, treatment should be based on informing the parents about sleep physiology and on training them in sleep hygiene and the acquisition of sleep habits. When pharmacological treatment is required, it should be carefully selected using the smallest effective doses. Melatonin seems to have a promising future in insomnia treatment in healthy children and in those with neurological disorders.

Sleep duration from infancy to adolescence: reference values and generational trends

OBJECTIVE

The main purpose of the present study was to calculate percentile curves for total sleep duration per 24 hours, for nighttime and for daytime sleep duration from early infancy to late adolescence to illustrate the developmental course and age-specific variability of these variables among subjects.

METHODS

A total of 493 subjects from the Zurich Longitudinal Studies were followed using structured sleep-related questionnaires at 1, 3, 6, 9, 12, 18, and 24 months after birth and then at annual intervals until 16 years of age. Gaussian percentiles for ages 3 months to 16 years were calculated for total sleep duration (time in bed) and nighttime and daytime sleep duration. The mean sleep duration for ages 1 to 16 years was estimated by generalized additive models based on the loess smoother; a cohort effect also had to be included. The standard deviation (SD) was estimated from the loess smoothed absolute residuals from the mean curve. For ages 3, 6, and 9 months, an alternative approach with a simple model linear in age was used. For age 1 month, empirical percentiles were calculated.

RESULTS

Total sleep duration decreased from an average of 14.2 hours (SD: 1.9 hours) at 6 months of age to an average of 8.1 hours (SD: 0.8 hours) at 16 years of age. The variance showed the same declining trend: the interquartile range at 6 months after birth was 2.5 hours, whereas at 16 years of age, it was only 1.0 hours. Total sleep duration decreased across the studied cohorts (1974-1993) because of increasingly later bedtime but unchanged wake time across decades. Consolidation of nocturnal sleep occurred during the first 12 months after birth with a decreasing trend of daytime sleep. This resulted in a small increase of nighttime sleep duration by 1 year of age (mean 11.0 +/- 1.1 hours at 1 month to 11.7 +/- 1.0 hours at 1 year of age). The most prominent decline in napping habits occurred between 1.5 years of age (96.4% of all children) and 4 years of age (35.4%).

CONCLUSIONS

Percentile curves provide valuable information on developmental course and age-specific variability of sleep duration for the health care professional who deals with sleep problems in pediatric practice.

Preventing sleeping problems in infants who are at risk of developing them

AIMS

(1) To identify factors at 1 week of age which put infants at risk of failing to sleep through the night at 12 weeks of age. (2) To assess whether a behavioural programme increases the likelihood that these infants will sleep through the night at 12 weeks of age.

METHODS

A community sample of 316 newborn infants was employed to identify the risk factors at 1 week of age which increased the likelihood of failing to sleep through the night at 12 weeks of age. Infants who met these risk criteria and were randomly assigned to a behavioural programme were compared with at risk infants in the control group on measures of sleeping, crying, and feeding at 12 weeks of age.

RESULTS

Infants who had a high number (>11) of feeds in 24 hours at 1 week were 2.7 times (95% CI 1.5 to 4.8) more likely than other control group infants to fail to sleep through the night at 12 weeks of age. At 12 weeks, 82% of these at risk infants assigned to the behavioural programme, compared to 61% in the control group, slept through the night. The findings were similar in breast and bottle feeders.

CONCLUSIONS

Preventing infant sleeping problems should be more cost effective than treating them after they have arisen. This study provides evidence that it is possible to identify infants who are at risk of failing to sleep through the night at an early age, and that a simple, three step, preventive behavioural programme increases the number who sleep through the night by 21%.

Attention to infants in the first year

The time spent by 158 infants in contact with their carers at 6, 13, 26 and 52 weeks was reviewed prospectively. Periods of contact in the categories of (1) physical care, (2) holding the crying or sleeping infant, and (3) playing and interacting with the infant were recorded using 24-h log diaries completed by the mother. The mean total carer contact time over a 24-h day did not change significantly in the first year, varying between 6.5 and 73 h. Between 6 and 52 weeks, time spent by the mother in physical care declined significantly from 207 to 143 min and in holding the crying or sleeping infant from 61 to 17 min (P < 0.05 and 0.0001 respectively). There were no significant changes in the amount of time spent in playing and interacting with the infant over the first year by the mother and father, the time being on average 52.7 and 25.0 min respectively. Play and interaction with a non-parental carer increased significantly from 14 to 69 min (P < 0.0001). Relationships between infant size and holding became weaker as the infant became older. Infant gender, socioeconomic status and duration of breast-feeding did not influence infant contact time.

Bed sharing patterns in a cohort of Australian infants during the first six months after birth

OBJECTIVE

To measure bed sharing (BS) activity in healthy term infants.

METHODOLOGY

The sleep-wake behaviour and place of infant sleep were recorded for infants aged between 2 and 24 weeks. Infants were then identified as BS or non bed sharing (NBS) according to each of four different definitions of bed sharing.

RESULTS

The mean proportion of infants who spent any time BS during a 24-h period was significantly greater (P < 0.05) between 2 and 12 weeks (40.9 +/- 1. 4%) than between 13 and 24 weeks (36.5 +/- 1.5%). A significantly greater proportion (P < 0.005) of infants bed shared for more than 2 h (25 +/- 1%) than for either 1-2 h (10.5 +/- 1.1%) or for less than 1 h/24 h (3.2 +/- 0.5%) during the whole study period. Each of the definitions of BS used in the study separated infants on the basis of the amount and frequency of BS activity.

CONCLUSION

: Bed sharing activity was common and varied in this cohort. It was possible, using quantitative definitions, to identify those infants who routinely bed share.

Ultradian and circadian rhythms of sleep-wake and food-intake behavior during early infancy

The early development of sleep-wake and food-intake rhythms in human infants is reviewed. The development of a 24 h day-night rhythm contains two observable developmental processes: the alterations in the periodic structure of behavior (decreased ultradian, increased circadian components) and the process of synchronization to external time (entrainment). The authors present the results of their studies involving 26 German children and compare them with previous investigations. In their research, it became evident that, during the first weeks of life, the time pattern of sleep-wake and food-intake behavior is characterized by different ultradian periodicities, ranging from 2 h to 8 h. In the course of further ontogenesis, the share of ultradian rhythms in the sleep-wake behavior decreases, while it remains dominant for food-intake behavior. The circadian component is established as early as the first weeks of life and increases in the months that follow. Besides, the authors' study supports the notion of broad interindividual variation in ultradian rhythms and in the development of a day-night rhythm. Examples of free-running rhythms of sleep-wake and food-intake behavior by various authors are strong indicators of the endogenous nature of the circadian rhythms in infants and show that the internal clock is already functioning at birth. It is still uncertain when the process of synchronization to external and social time cues begins and how differences in the maturation of perceptive organs affect the importance of time cues for the entrainment. Prepartally, the physiological maternal entrainment factors and mother-fetus interactions may be most important; during the first weeks of life, the social time cues gain importance, while light acts as a dominant "zeitgeber" at a later time only.

Duration and pattern of crying in the first year of life

In a prospective study of fetal and postnatal growth and development in a group of babies whose mothers were residents of an inner-city health district in the north of England, the total amount of crying of 157 infants was recorded at four periods during the first year of life by means of a 24-hour log. The mean number of crying episodes reduced from 4.4 at six weeks to 1.5 at one year. Early crying predicted later crying. It was not possible to predict which babies would cry a lot except that breast-fed infants tended to cry less. Mothers' perceptions of whether their babies cried a lot correlated with their perception of sleep difficulties. Rapid response to crying was associated with significantly less crying overall.

Sleep problems in childhood

Sleep, like eating and toileting, is an individual physical requirement that changes with time as the child matures. Although much about a child's sleep is biologically determined, extrinsic factors, usually through the parents, also mold the child's sleep behavior. Normal sleep for a child is restful to the child and not excessively disruptive to others. Sleep problems interfere with the quality of the child's sleep and frustrate or frighten caretakers. Several sleep problems have their origins in normal sleep behavior from an earlier age. Some, the parasomnias, are caused by self-limited biologic diatheses. Many sleep problems have psychosocial triggers. Sleep disorders only rarely are a primary medical problem that is adequately treated with medication (e.g., narcolepsy). Good history-taking, often accompanied by diary-keeping, will usually identify the problem--the first step in effective treatment. Treatment of a sleep disorder in the pediatrician's office can start with educating caretakers about normative sleep for the age of the child and providing information regarding the cause and natural course of the problem. Treatment also may involve behavioral or psychological intervention or both, but medication is generally not indicated. When needed for short-term treatment, mild sedatives such as antihistamines are used most often. More serious sleep or behavioral problems should be acknowledged by the primary care pediatrician, followed by referral to an appropriate specialist. Inquiry into a child's sleep habits at each well-child visit, coupled with appropriate anticipatory guidance, could make an important contribution to the child and family by preventing problems with sleep and identifying sleep problems early in their evolution. Pediatricians and parents can work together to help children develop good sleep habits that fulfill the child's evolving sleep requirements within the context of the family's needs and expectations.