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Aims: This study sought to determine whether not sleeping soundly in early infancy predicted poor development. This complemented earlier studies of children aged 12 months or older. Methods: Sleep/wake patterns of 35 Japanese infants (23 males) with a gestational age of 37< weeks were recorded at home using actigraphy. Families were registered with a laboratory-based database for infant research. Follow-up recordings were conducted at 3, 4, 6, 12, and 24 months. Crawling was rated by mothers at 12 months and used to create regular and irregular crawling groups. Temperament was scaled using the Japanese Infant Behaviour Questionnaire-Revised Questionnaire and the Japanese Early Childhood Behaviour Questionnaire. Results: At 4 months, infants with regular crawling style had shorter night-time sleep than infants with irregular crawling style. However, at 12 months, the former had longer motionless sleep at night compared to the latter. Before 6 months, infants with regular crawling style showed lower sleep efficiency, especially during the day, compared to those with irregular crawling style. In addition, the amount of night-time active sleep at 3 and 4 months were positively correlated with day-time activity, but not at 6 months. Conclusion: Short fragmental sleep in early infancy did not always predict poor development. [ABSTRACT FROM AUTHOR]

The objective of the present study was to confirm the link between spontaneous smiling and active sleep in newborns, and to identify the role of the cortex in the generation of spontaneous smiles. A total of 12 healthy newborns born at term and three infants with major congenital abnormalities (two with hydranencephaly and one with a left hemispherectomy) were evaluated by video and polysomnography during a 3‐hr sleep period. Smiles were graded and their association with isolated rapid eye movements and grouped rapid eye movements was analysed. In all, 383 smiles were recorded of which 377 occurred during active sleep. Smiles were shown to be significantly associated with active sleep (p <.0001) and with grouped rapid eye movements (p <.0001). Bilateral smiles were more frequent than asymmetrical smiles. Among asymmetrical smiles, left‐sided smiles were more frequent than right‐sided smiles (p <.0001). Maternal stimulation during active sleep did not increase smiles. Smiling was absent during active sleep only in the infant with total hydranencephaly in whom nearly all cortical tissue was absent. In conclusion, smiling occurs in healthy newborns, almost exclusively in active sleep and is associated with grouped rapid eye movements. In infants with major congenital abnormalities, smiling is abolished only when nearly all of the cerebral cortex is absent. These results support the hypothesis of the role of active sleep in the stimulation of neuronal circuits responsible for spontaneous smiling and emphasise the importance of cortical areas in newborn smiling. [ABSTRACT FROM AUTHOR]

During the perinatal period in mammals when active sleep predominates, skeletal muscles twitch throughout the body. We have hypothesized that myoclonic twitches provide unique insight into the functional status of the human infant's nervous system. However, assessments of the rate and patterning of twitching have largely been restricted to infant rodents. Thus, here we analyze twitching in human infants over the first seven postnatal months. Using videography and behavioral measures of twitching during bouts of daytime sleep, we find at all ages that twitching across the body occurs predominantly in bursts at intervals of 10 s or less. We also find that twitching is expressed differentially across the body and with age. For example, twitching of the face and head is most prevalent shortly after birth and decreases over the first several months. In addition, twitching of the hands and feet occurs at a consistently higher rate than does twitching elsewhere in the body. Finally, the patterning of twitching becomes more structured with age, with twitches of the left and right hands and feet exhibiting the strongest coupling. Altogether, these findings support the notion that twitches can provide a unique source of information about typical and atypical sensorimotor development. [ABSTRACT FROM AUTHOR]

There is a growing realization that proper sleep during pregnancy is essential for the health of the mother and the offspring. However, there are no reports on the effects of maternal sleep restriction on the sleep-wake profiles of newborns. So, this study was conducted to evaluate the effects of sleep restriction during the third term of pregnancy on the sleep-wake profiles of neonates born to them. The female pregnant Wistar rats were sleep restricted for 5 h/day on gestational days 15–20 by gentle handling. Sleep-wake profiles of the pups born to them and to the control rats were recorded on postnatal days 1–21. Pups of sleep restricted dams had higher active sleep (AS) and lower quiet sleep (QS) as well as wakefulness. Higher ratio of AS to QS, longer duration of sleep cycles, lesser bout frequency and reduced EEG delta power were also observed in these pups, all of which indicated brain immaturity. All these signs of delayed maturation, usually found in premature babies, were observed in the pups of sleep restricted mothers, who had longer gestation period. This report not only shows the importance of sleep during pregnancy, but it also suggests that neonatal sleep monitoring can be used as a tool for early assessment of retarded brain development. [ABSTRACT FROM AUTHOR]

Morphology and late components of evoked potentials change depending on wake-sleep stages in adults. Visual Evoked potentials (VEPs) have been frequently studied in newborns to identify abnormal development of visual pathways; however, large variability has been reported and there is uncertainty as to the effect of sleep stages on VEPs in neonates. Objective To describe the characteristics of VEPs in one month old, healthy full-term newborns during active sleep (AS) and quiet sleep (QS), defined by simultaneous polysomnography (PSG). Methods VEPs were obtained by monocular LEDs stimulation of each eye during AS and QS, in 20 healthy full-term newborns (gestational age 37–40 weeks) with normal birth weights and normal prenatal Doppler ultrasound indices. Latencies and amplitudes of N2, P2 and N3 components in AS and QS were compared, and their association with absolute power of EEG frequency bands, assessed. Results There were no significant differences in VEP morphology, latencies and amplitudes between sleep states. Typical wave forms were obtained in all newborns in AS; however, no VEPs could be identified clearly in 3 newborns in QS; QS VEPs were less reliable than in AS: more averaging was required; correlation was significantly lower between the VEP averages; and a larger number of babies needed more than two averages to obtain replicable responses needed for clinical purposes. Conclusions These results indicate that changes in amplitude and latency of some VEP components observed in NREM and REM sleep in adults are not yet present in one month old newborns probably due to immaturity of cortical and sleep mechanisms. VEPs are more reliable during AS than QS in newborns. Systematic VEP recording during AS, and polysomnographic control to identify this stage, are highly recommended as methods that can increase there liability of neonatal VEPs. [ABSTRACT FROM AUTHOR]

ABSTRACT Despite the ubiquitous nature of sleep, its functions remain a mystery. In an attempt to address this, many researchers have studied behavioural and electrophysiological phenomena associated with sleep in a diversity of animals. The great majority of vertebrates and invertebrates display a phase of immobility that could be considered as a sort of sleep. Terrestrial mammals and birds, both homeotherms, show two sleep states with distinct behavioural and electrophysiological features. However, whether these features have evolved independently in each clade or were inherited from a common ancestor remains unknown. Unfortunately, amphibians and reptiles, key taxa in understanding the evolution of sleep given their position at the base of the tetrapod and amniote tree, respectively, remain poorly studied in the context of sleep. This review presents an overview of what is known about sleep in amphibians and reptiles and uses the existing data to provide a preliminary analysis of the evolution of behavioural and electrophysiological features of sleep in amphibians and reptiles. We also discuss the problems associated with analysing existing data, as well as the difficulty in inferring homologies of sleep stages based on limited data in the context of an essentially mammalian-centric definition of sleep. Finally, we highlight the importance of developing comparative approaches to sleep research that may benefit from the great diversity of species with different ecologies and morphologies in order to understand the evolution and functions of sleep. [ABSTRACT FROM AUTHOR]

Aims: This study sought to determine whether not sleeping soundly in early infancy predicted poor development. This complemented earlier studies of children aged 12 months or older., Methods: Sleep/wake patterns of 35 Japanese infants (23 males) with a gestational age of 37< weeks were recorded at home using actigraphy. Families were registered with a laboratory-based database for infant research. Follow-up recordings were conducted at 3, 4, 6, 12, and 24 months. Crawling was rated by mothers at 12 months and used to create regular and irregular crawling groups. Temperament was scaled using the Japanese Infant Behaviour Questionnaire-Revised Questionnaire and the Japanese Early Childhood Behaviour Questionnaire., Results: At 4 months, infants with regular crawling style had shorter night-time sleep than infants with irregular crawling style. However, at 12 months, the former had longer motionless sleep at night compared to the latter. Before 6 months, infants with regular crawling style showed lower sleep efficiency, especially during the day, compared to those with irregular crawling style. In addition, the amount of night-time active sleep at 3 and 4 months were positively correlated with day-time activity, but not at 6 months., Conclusion: Short fragmental sleep in early infancy did not always predict poor development., (© 2022 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.)

Sleep, the brain and the ability to interact with the environment change a great deal over the first year of life; however, there are no studies on the possible influence of different environmental stimulations on the organization of subsequent sleep-wake cycles in infants. The hypothesis of this study was that greater continuity of contingent tactile stimulation decreases crying behavior, subsequent active sleep (AS) and its fragmentation, and increases smiling behavior and subsequent quiet sleep in newborns. Forty out of the 82 newborns (15- to 30-hr old) of the initial sample satisfied the inclusion criteria and completed the first cycle of sleep during the period between two feedings. The 40 newborns were randomly assigned to four groups after 2′ of baseline observation: continuous stimulation (CS, n = 10); discontinuous nonperiodic stimulation (DnPS, n = 10); discontinuous periodic stimulation (DPS, n = 10); absent stimulation (AbS, n = 10). During baseline measurements, there were no significant differences in crying and smiling behaviors between the four groups, while during the subsequent stimulated wake, the CS group compared to the DnPS group showed more smiling ( p < .05) and less crying ( p < .05), longer poststimulation wake before sleep ( p < .01) as well as AS with a lower percentage of grouped-rapid eye movements [grouped REM (GREM); p < .001]. The number of GREM during AS was negatively correlated to the number of smiles ( p < .05) and positively to the number of cries ( p < .05) of the previous stimulated wake. These findings suggest that, after birth, different continuity levels of contingent tactile stimulations may affect crying and smiling behaviors and the organization of behavioral states. AS could have an important role in processing affective states. © 2012 Wiley Periodicals, Inc. Dev Psychobiol 55: 508-517, 2013 [ABSTRACT FROM AUTHOR]

Aims: To investigate the correlation between the ‘perfusion index’ (PI) and other commonly used estimates of cutaneous blood flow [heart rate (HR), surface temperatures (ST) and central-to-peripheral thermal gradients (C-P grad)] and to use this new non-invasive tool to compare differences between prone and supine sleep position in low birth weight (LBW) infants. Methods: Six-hour continuous recordings of pulse oximetry, cardiac activity and absolute ST from three sites (flank, forearm and leg), along with minute-to-minute assessment of behavioural states were performed in 31 LBW infants. Infants were randomly assigned to the prone or supine position for the first 3 h and then reversed for the second 3 h. PI data were correlated with HR and C-P grad, and compared across sleep positions during quiet sleep (QS) and active sleep (AS). Results: Perfusion index correlated significantly with HR (r2 = 0.40) and flank-to-forearm thermal gradient (r2 = 0.28). In the prone position during QS, infants exhibited higher PI (3.7 ± 0.9 vs. 3.1 ± 0.7), HR (158.4 ± 8.9 vs. 154.1 ± 8.8 bpm), SpO2 (95.8 ± 2.6 vs. 95.2 ± 2.6%), flank (36.7 ± 0.4 vs. 36.5 ± 0.4°C), forearm (36.1 ± 0.6 vs. 35.5 ± 0.4°C) and leg (35.4 ± 0.7 vs. 34.7 ± 0.7°C) temperatures and narrower flank-to-forearm (0.6 ± 0.4 vs. 0.9 ± 0.3°C) and flank-to-leg (1.3 ± 0.6 vs. 1.8 ± 0.7°C) gradients, compared to those of the supine position. Similar differences were observed during AS. Conclusion: Perfusion index is a good non-invasive estimate of tissue perfusion. Prone sleeping position is associated with a higher PI, possibly reflecting thermoregulatory adjustments in cardiovascular control. The effects of these position-related changes may have important implications for the increased risk for sudden infant death syndrome in prone position. [ABSTRACT FROM AUTHOR]

In infants most previous studies of the hypoxic ventilatory response (HVR) have been conducted only during quiet sleep (QS) and arousal responses have not been considered. Our aim was to quantify the maturation of the HVR in term infants during both active sleep (AS) and QS over the first 6 months of life. Daytime polysomnography was performed on 15 healthy term infants at 2–5 weeks, 2–3 and 5–6 months after birth and infants were challenged with hypoxia (15% O2, balance N2). Tests in AS always resulted in arousal; in QS tests infants either aroused or did not arouse. A biphasic HVR was observed in non arousing tests at all three ages studied. The fall in SpO2 was more rapid in arousal tests at all three ages. At 2–5 weeks, in non-arousing QS tests, there was a greater fall in respiratory frequency ( f) despite a smaller fall in SpO2 compared with 2–3 and 5–6 months. When infants aroused there was no difference in the HVR between sleep states or with postnatal age. However, when infants failed to arouse from QS, arterial desaturation was less in the younger infants despite a poorer HVR. We suggest that arousal in response to hypoxia, particularly in AS, is a vital survival mechanism throughout the first 6 months of life. [ABSTRACT FROM AUTHOR]

SUMMARY Newborn mammals spend as much as 90% or more of their time in a sleep state characterized by frequent twitches, rapid eye movements (REMs), and irregular respiratory cycles. These motor and respiratory patterns resemble the phasic motor/respiratory components of adult REM sleep, and as a consequence, this sleep state is traditionally viewed as an immature form of REM sleep. An alternative view is that a significant portion of what has been called REM sleep in these species is a form of spontaneous activity typical of the immature nervous system. In this review, we compare and contrast these two opposing views about the ontogenetic origins of REM sleep, and review the evidence most often cited to support the idea that REM sleep is present in newborn altricial mammals. Critical review of this evidence indicates that REM sleep may not be present at birth in these species; rather, it appears that all mammals early in development exhibit spontaneous, dissociated activity that progressively becomes organized into the distinct states of REM and non-rapid eye movement sleep. [ABSTRACT FROM AUTHOR]

There are suggestions in the literature that the electroencephalographic (FIG) desynchronization response is in the newborn's repertoire. The present investigation was designed to examine that possibility under stringent experimental conditions. Sixteen normal neonates were presented with a 1-sec pure tone or white noise during one episode of quiet sleep and one episode of active sleep. Flat activity during stimulated quiet sleep was compared with spontaneous periods of low voltage activity during a nonstimulated quiet sleep episode. Comparisons were also made between responses in quiet sleep with and without prior stimulation in active sleep. Habituation and dishabituation were studied by presenting the nonfamiliar stimulus after repetition of the original stimulus. Increased EEG desynchronization to stimulation was found but the response appears to be a complex function of the type of stimulus, recording location, stimulus repetition, and the prior experience variable. The results have implications for differential maturation of the brain, the perceptual capacities of the neonate, and the controversy over orientation in the newborn. [ABSTRACT FROM AUTHOR]

The present study investigated the applicability of the Law of Initial Value (LIV) for heart rate (HR) responses evoked by a nociceptive stimulus in neonatal sleep states. Ten infants were tested during Quiet and Active Sleep. In concordance with the LIV there was a significant inverse correlation for all Ss in Active Sleep between HR change and prestimulus HR values; the average correlation was -.76, the average slope -.48. In Quiet Sleep, which had a small prestimu1us HR range, this relationship was significant only for some Ss. Equating for prestimulus HR values, no significant difference existed in the magnitude of average HR response in Active Sleep vs Quiet Sleep. It was concluded that for nociceptive stimuli the initial HR value is a better predictor than the behavioral sleep state of the magnitude of HR response. It is suggested that the LIV depends largely on the modality and strength of the stimulus and the width of the prestimulus HR range. [ABSTRACT FROM AUTHOR]