Newborn temperament and Sudden Infant Death Syndrome: A comparison of victims and their cotwins

Temperament assessed in the newborn period was compared for four twin infants who subsequently died of Sudden Infant Death Syndrome (SIDS) and their surviving cotwins. The assessment focused on irritability, resistance to soothing, reactivity, reinforcement value, activity while awake, and activity during sleep. No differences were observed between cotwins on a combined irritability rating. SIDS victims, however, were less irritable than their siblings in response to aversive stimuli. When irritable, the SIDS infants were more difficult to soothe than their cotwins. While awake, SIDS infants were less active than their cotwins, but during sleep, no activity differences were observed. The SIDS infants were more reactive to orienting stimuli, and neither group was found to be more or less rewarding to the examiner. It was concluded that this study has helped to define behavioral variables that might be characteristic of infants whose subsequent deaths are attributed to SIDS.     

Interventions in early infancy

Infants of high-risk pregnancies and deliveries may need early intervention to facilitate attachment both to and from their caregivers. Three early interventions are described: (1) giving high-risk pregnant women video feedback during prenatal ultrasound, which reduced maternal anxiety, obstetric complications, and fetal activity and improved neonatal outcome (increased weight gain, better performance on the Brazelton, and decreased irritability); (2) providing preterm neonates nonnutritive sucking opportunities to reduce stress during heelsticks and gavage feedings; and (3) providing preterm neonates and preterm cocaine-exposed neonates massage therapy, which facilitated weight gain and better performance on the Brazelton scale. Following improved neonatal behavior, infants would be expected to have better interactions with their caregivers.     

Sleep and Infant Learning

Human neonates spend the majority of their time sleeping. Despite the limited waking hours available for environmental exploration, the first few months of life are a time of rapid learning about the environment. The organization of neonate sleep differs qualitatively from adult sleep, and the unique characteristics of neonatal sleep may promote learning. Sleep contributes to infant learning in multiple ways. First, sleep facilitates neural maturation, thereby preparing infants to process and explore the environment in increasingly sophisticated ways. Second, sleep plays a role in memory consolidation of material presented while the infant was awake. Finally, emerging evidence indicates that infants process sensory stimuli and learn about contingencies in their environment even while asleep. As infants make the transition from reflexive to cortically mediated control, learned responses to physiological challenges during sleep may be critical adaptations to promote infant survival.     

Exclusive breastfeeding at three months and infant sleep-wake behaviors at two weeks,three and six months

This study assessed infant sleep-wake behavior at two weeks, three and six months as function of feeding method at three months (exclusively breastfed, partially breastfed, and exclusively formula fed infants). Mothers of 163 first-born, full-term, normal birth weight, healthy infants completed socio-demographic, depression, anxiety, and infant sleep-wake behavior measures. No effects were found for sleep arrangements, depression or anxiety, on feeding methods and sleep-wake behavior at three months. At two weeks exclusively breastfed infants at three months spent more hours sleeping and less hours awake during the 24-h period than partially breastfed infants. At three months, exclusively breastfed infants had a shorter of the longest sleep period at night than exclusively formula fed infants. At six months, exclusively breastfed infants at three months spent more hours awake at night than partially breastfed infants, awake more at night than exclusively formula fed infants, and had a shorter sleep period at night than partially breastfed and exclusively formula fed infants. This study showed differences in sleep-wake behaviors at two weeks, three and six months, when exclusively breastfed infants are compared with partially breastfed and exclusively formula fed infants at three months, while no effects were found for sleep arrangements, depression or anxiety.     

The effect of neonatal temperament on caregiver behavior in the newborn nursery

The research was conducted to determine whether temperamental characteristics of neonates influence caregiver behavior as early as the second day of life. Visual attentiveness, activity, and irritability of 28 healthy newborns were rated during six 30-minute sessions. Derived scores represented the infant's behavior during the total observation time and during specified caretaking activities. Several categories of nurturant behaviors and types of comments directed toward each infant by nurse-caregivers were coded during independent sessions. Variations in caregiver behavior were shown by Pearson correlations to be related to independently assessed differences among neonates. Alert babies received the most nurturant and social contact; active infants received the least contact, but the most comments that reflected concern about their health; irritable infants were soothed most. The data clearly suggest that emerging infant temperament plays a role in shaping the caregiving environment by the second day of life.     

睡眠不足对人际交互的影响及其认知神经机制

睡眠不足会对人的认知、情感和人际交互产生诸多影响。这种影响在社会情绪层面表现为个体情绪共情和认知共情的减少,易激惹性与愤怒情绪的增加;在社会行为层面则表现为亲社会行为的减少和攻击行为的增加。在睡眠不足状态下,情绪系统和认知系统功能连接的减弱可能是这些变化的潜在机制。未来应结合生态效度较高的睡眠操作手段,系统考察睡眠不足如何导致各种高级社会情绪的改变,以及这些社会情绪的变化如何导致社会行为的变化。     

Rapid eye movement (REM) in premature neonates and developmental outcome at 6 months

Different aspects of early sleep organization have been associated with subsequent development in premature infants. The aim of the present study was to assess the relations between rapid eye movement (REM) activity in premature neonates and infants' developmental outcomes at 6 months. Participants were 81 premature infants (47 males). Sleep-wake states and REM were observed across 4 consecutive evening hours (7-11 PM) in 10-s frames when infants were between 32 and 36 weeks post-menstrual age. Developmental outcome was assessed at 6 months with the mental development index (MDI) of the Bayley II. Infants with low-REM activity spent more time in less growth-promoting states, including crying and unfocused alert states in the neonatal period and had lower MDI scores at 6 months corrected age compared to infants with high-REM. Differences between the high- and low-REM groups were independent of neonatal medical risk. Low-REM activity may serve as an indicator of developmental risk among premature neonates.     

Neonatal functioning and the sudden infant death syndrome

A male infant, diagnosed as a Sudden Infant Death Syndrome (SIDS) at 5 months, 3 weeks, had been extensively tested as a part of a larger sample in a longitudinal study. The longitudinal sample was comprised of 137 clinically normal neonates, born to intact upper middle-class families, living in a large metropolitan area. A neonatal assessment consisted of 5 hours of polygraphic recordings of heart and respiratory rate during sleep and waking cycles, and 1 hour of behavioral testing. At 3 months of age the infant was observed for 12 hours in the home. Retrospective analyses of these data suggested that: (a) neonatal respiratory behavior during sleep did not distinguish this infant from a sample of control infants; (b) the infant lacked strength in movements requiring the involvement of shoulder and neck muscles (head lift from a prone position); and (c) informal observations by skilled and experienced observers distinguished this infant from the sample of controls.     

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 13.3 h, spend 8.7 h awake, awake 6.1 times, have 0.4 h of latency to sleep, and 3.2 h of longest sleep period. Three-month-old infants sleep 13.0 h, spend 9.2 h awake, awake 5.5 times, have 0.4 h of latency to sleep, and 5.2 h of longest sleep period. Six-month-old infants sleep 12.2 h, spend 10.0 h awake, awake 5.2 times, have 0.4 h of latency to sleep, and 5.6 h 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.     

Differences in dimensionality of electroencephalogram during awake and deeper sleep stages

The nonlinear dynamical systems theory provides some tools for the analysis of electroencephalogram (EEG) at different sleep stages. Its use could allow the automatic monitoring of the states of the sleep and it would also contribute an explanatory level of the differences between stages. The goal of the present paper is to address this type of analysis, focusing on the most different stages. Estimations of dimensionality were compared when six subjects were awake and in a deep sleep stage. Greater dimensionality involves more complexity because the system receives more external influences. If this dimensionality is maximum, we can consider that the time series is a noisy one. A smaller dimensionality involves lower complexity because the system receives fewer inputs. We hypothesized that we would find greater dimensionality when subjects were awake than in a deep sleep stage. Results show a noisy time series during the awake stage, whereas in the sleep stage, dimensionality is smaller, confirming our hypothesis. This result is similar to the findings reached previously by other authors.     

Early affective antecedents of adult type A behavior

The early affective, apparently temperamental antecedents of Type A behavior were investigated in a Swedish longitudinal sample (N = 149). Four clusters of Type A items (describing irritability, hurried behavior, work achievement, and competitiveness) were regressed on maternal ratings of the child's poor appetite, sleep disturbances, liveliness, anger, and shyness, collected annually from infancy to adolescence. The child's liveliness, sociability, and poor appetite during infancy and childhood were positively related to the adult Type A irritability and hurried behavior clusters, as were the mother's liveliness, orderliness, and intelligence as rated by psychologists during the child's first 6 years. The two work-involvement clusters were predicted by interactive effects among shyness, poor appetite, and anger during adolescence but were unrelated to mother attributes. Sleep disturbances were only related to competitiveness and only in late adolescence. These findings indicate that the interrelated components of adult Type A behavior have contrasting developmental histories and that temperament-related constructs are important antecedents to the adult syndrome.     

Hippocampal sequences link past, present, and future

Disrupting the reactivation of hippocampal neurons during sleep impairs memory consolidation in rats. However, the functional importance of reactivation during awake states is unknown. An experiment in which awake reactivation was disrupted suggests that this phenomenon could adaptively guide behavior by linking previous learning with the current state of the world.     

Relation between reported maternal caffeine consumption during pregnancy and neonatal state and heart rate

Regression analyses showed that prenatal caffeine exposure in 50 neonates was predictive of higher heart rates overall and during quiet and active sleep after the effects of alcohol, nicotine and SES, and maternal age were statistically controlled. Separate effects also showed that lower SES was related to higher neonatal heart rates.     

Effects of prone and supine positions on sleep state and stress responses in preterm infants

Aim

The purpose of the study is to assess the influence of prone or supine position on sleep states and on withdrawal and approach reactions of preterm infants.

Methods

Thirty-two preterm infants from Meir Medical Center, Israel, mean post menstrual age 30.37 ± 2.57, mean birth weight 1250 g ± 313.86, participated in the study. Infants were studied during 48 h. Positions (prone and supine) were alternated every 3-4 h after feedings. Sleep states were assessed by Actigraph measurement and by two daily 30-min Naturalistic Observations of Newborn Behavior (NONB) to confirm sleep states and for recording the behavioral reactions (approach and withdrawal).

Results

In the prone position there were more approach reactions as compared to withdrawal reactions (p < .001) while in the supine position, the approach and withdrawal reactions were comparable. In the prone position more sleep patterns (deep sleep, light sleep, drowsy) were observed as opposed to more awake patterns (quiet awake, active awake and agitated fussy) that were seen in the supine position.

Conclusions

Clinical implications encourage placing the preterm infant in the prone position while in the NICU. This enables important achievements such as longer periods of quality sleep, and production of adaptive self-regulatory reactions.     

Cerebral blood flow in normal and abnormal sleep and dreaming

Measurements of regional or local cerebral blood flow (CBF) by the xenon-133 inhalation method and stable xenon computerized tomography CBF (CTCBF) method were made during relaxed wakefulness and different stages of REM and non-REM sleep in normal age-matched volunteers, narcoleptics, and sleep apneics. In the awake state, CBF values were reduced in both narcoleptics and sleep apneics in the brainstem and cerebellar regions. During sleep onset, whether REM or stage I-II, CBF values were paradoxically increased in narcoleptics but decreased severely in sleep apneics, while in normal volunteers they became diffusely but more moderately decreased. In REM sleep and dreaming CBF values greatly increased, particularly in right temporo-parietal regions in subjects experiencing both visual and auditory dreaming.     

Development of sleep/wake,activity and temperature rhythms in newborns maintained in a neonatal intensive care unit and the impact of feeding schedules

Biological rhythms in infants are described as evolving from an ultradian to a circadian pattern along the first months of life. Recently, the use of actigraphy and thermistors with memory has contributed to the understanding of temporal relations of different variables along development. The aim of this study was to describe and compare the development of the rhythmic pattern of wrist temperature, activity/rest cycle, sleep/wake and feeding behavior in term and preterm newborns maintained in a neonatal intensive care unit (NICU).MethodsNineteen healthy preterm and seven fullterm newborns had the following variables monitored continuously while they were in the NICU: activity recorded by actigraphy, wrist temperature recorded with a thermistor and observed sleep and feeding behavior recorded by the NICU staff with diaries. Subjects were divided in 3 groups according to their gestational age at birth and rhythmic parameters were compared.ResultsA dominant daily rhythm was observed for wrist temperature since the first two weeks of life and no age relation was demonstrated. Otherwise, a daily pattern in activity/rest cycle was observed for most preterm newborns since 35 weeks of postconceptional age and was more robust in term babies. Feeding and sleep/wake data showed an almost exclusive 3 h rhythm, probably related to a masking effect of feeding schedules.ConclusionsWe found that wrist temperature develops a daily pattern as soon as previously reported for rectal temperature, and with acrophase profile similar to adults. Moreover, we were able to find a daily rhythm in activity/rest cycle earlier than previously reported in literature. We also suggest that sleep/wake rhythm and feeding behavior follow independent developmental courses, being more suitable to masking effects.     

Male-female differences and the influence of neonatal and adult testosterone on intraspecies aggression in rats.

Male and female albino rats were tested for intraspecies aggression without the use of shock. In the first experiment, male pairs showed more biting attacks, offensive sideways movements, and self-grooming than did female pairs; male pairs also showed more stereotyped defensive/submissive behaviors and were wounded more frequently. The second experiment examined the effects of neonatal castration and testosterone propionate (TP) administration on fighting. Males castrated at birth attacked other males less frequently than did controls when tested with TP treatment as adults. The TP given at birth to neonatally castrated males restored attacks to control levels. Females given TP as neonates did not differ from either male or female controls. Other aggressive/defensive behaviors, however, did not show this pattern. The results suggest that while the presence of testosterone during a brief postnatal period and during adulthood is necessary for attack behavior to occur, other related behaviors may not be affected in a similar manner.     

Hypersomnia and the perception of sleep-wake states: some preliminary findings

35 hypersomniacs (20 with obstructive sleep apnea and 15 with narcolepsy) and 15 controls estimated sleep latency during systematic trials of attempting to remain awake during the day. The error in subjective assessment of sleep latency was more variable for both patient groups than for controls. In addition, narcoleptics could not provide a determination of sleep latency or differentiate sleep-wake states on nearly 23% of all trials. Ratings on a subjective sleepiness scale did not covary with objective sleep latency for any hypersomniac. The findings suggested that patients with either sleep apnea or narcolepsy had difficulty differentiating sleep and quiet wakefulness during the day.     

Tryptophan and interpersonal spin

Increased serotonergic activity is often described as increasing the inhibition of behaviors. This study examined the more general hypothesis that increased serotonergic activity produces greater control over social behavior. Participants were drawn from two samples, individuals elevated on irritability and individuals unselected on personality characteristics. Individuals participated in a double blind cross-over design, providing event contingent records about their behavior during two 9-day periods which involved taking tryptophan or placebo. When taking tryptophan (which increases serotonergic activity), within-person variability among social behaviors across events (i.e., interpersonal spin) was reduced for irritable individuals, particularly those low on trait Agreeableness. These results suggest that higher levels of serotonergic activity enhance greater control and consistency in social behavior among irritable–disagreeable individuals.