Coffee and other caffeinated beverages are commonly consumed in pregnancy. In adults, caffeine may interfere with sleep onset and have a dose-response effect similar to those seen during insomnia. In infancy, nighttime waking is a common event. With this study, we aimed to investigate if maternal caffeine consumption during pregnancy and lactation leads to frequent nocturnal awakening among infants at 3 months of age.
All children born in the city of Pelotas, Brazil, during 2004 were enrolled on a cohort study. Mothers were interviewed at delivery and after 3 months to obtain information on caffeine drinking consumption, sociodemographic, reproductive, and behavioral characteristics. Infant sleeping pattern in the previous 15 days was obtained from a subsample. Night waking was defined as an episode of infant arousal that woke the parents during nighttime. Multivariable analysis was performed by using Poisson regression.
The subsample included 885 of the 4231 infants born in 2004. All but 1 mother consumed caffeine in pregnancy. Nearly 20% were heavy consumers (≥300 mg/day) during pregnancy and 14.3% at 3 months postpartum. Prevalence of frequent nighttime awakeners (>3 episodes per night) was 13.8% (95% confidence interval: 11.5%–16.0%). The highest prevalence ratio was observed among breastfed infants from mothers consuming ≥300 mg/day during the whole pregnancy and in the postpartum period (1.65; 95% confidence interval: 0.86–3.17) but at a nonsignificant level.
Caffeine consumption during pregnancy and by nursing mothers seems not to have consequences on sleep of infants at the age of 3 months.
sleep; sleep duration; infant sleeping; night waking; infant; caffeine; coffee
Infants born preterm are at elevated risk for social emotional difficulties. However, factors contributing to this risk are largely understudied. Within the present study, we explored infant sleep as a biosocial factor that may play a role in infant social emotional development. Within a prospective longitudinal design, we examined parent-reported sleep patterns and observed parenting quality as predictors of infant-mother attachment in 171 infants born preterm. Using structural equation modeling, we examined main effect and moderator models linking infant sleep patterns and parenting with attachment security. Sleep patterns characterized by more daytime sleep and positive/responsive parenting predicted infant attachment security. Parent-reported nighttime sleep patterns were unrelated to attachment in this sample of infants born preterm. These results indicate that daytime sleep and parenting quality may be important for emerging attachment relationships in infants born preterm.
sleep; attachment; preterm
Following a transactional perspective, this longitudinal study assessed concurrent and time-lagged associations between infant daytime sleep behaviors and maternal play interactions within a sample of infants born preterm.
Data were collected from 134 families recruited from 3 Wisconsin NICUs. Multiple methods were used to collect data at infant NICU discharge and when infants were 4, 9, and 24 months postterm, including parent-report infant sleep logs, family sociodemographic assets and a 15 minute video-taped play session.
Within time points, infants who napped more had mothers who were rated as more positive and communicative or less negative during play interactions at 4, 9 and 24 months compared to infants who napped less. Time-lagged findings indicated that infants who took more naps experienced more optimal maternal interactive behaviors later in development than infants who took fewer naps. Additionally, mothers who expressed more negative affect at 4 months or 9 months predicted more infant daytime sleep later in development.
Previous studies document that nighttime parent-child interactions influence nighttime sleep. This study presents the natural extension that daytime sleep influences daytime interactions. The present study draws attention to the understudied area of daytime naps in young children and provides support for the longitudinal bi-directional processes between sleep and parenting interactions.
Preterm; Sleep; Parenting
Predictors of maternal depression trajectories were examined longitudinally in families with an infant born preterm or low birthweight. A total of 181 mother-infant dyads enrolled in the study prior to the infant’s NICU discharge. Maternal depressive symptoms were assessed at five timepoints, and contextual variables and infant risks were assessed at NICU discharge. Hierarchical linear models revealed that mothers who experienced more risk factors reported more depressive symptoms just prior to their infant’s NICU discharge and showed less decline in depressive symptoms in the months immediately following the child’s birth. Although cumulative risks predicted depression trajectories, this effect appeared driven by maternal and family sociodemographic risks rather than infant risks. Addition of family support as a covariate in the multilevel models with a subsample of families revealed that social support and depression covaried across time. However, most of the findings regarding the association between risk and depression remained consistent, whereas the effects of maternal race and multiple birth were slightly attenuated.
cumulative risks; family support; low birthweight; maternal depression; preterm
STUDY OBJECTIVE--To describe the effect of different social and demographic characteristics on low birth weight (LBW) (less than 2500 g) in Spain, in both preterm (less than 37 weeks' gestation) and term infants (between 37 and 42 weeks' gestation). DESIGN--The study used data obtained from the Spanish birth registry. SETTING--The study was based on those live born infants registered in 1988 from provinces where the birthweight details were completed in at least 99.5% of the birth registration records. PARTICIPANTS--A total of 1332 preterm LBW infants, 1292 term LBW infants, and 38,967 controls were included in the study. MEASUREMENTS AND MAIN RESULTS--The odds ratio (OR) calculated by logistic regression was used as the measure of association between LBW and the sociodemographic variables. The highest ORs of preterm LBW were found in mothers younger than 20 years (1.32; 95% CI 0.98, 1.77) and older than 34 years (1.28; 95% CI 1.04, 1.59), in unmarried mothers (1.68; 95% CI 1.36, 2.07), and in fathers with manual occupations (1.26; 95% CI 1.08, 1.46). In term, live born infants the highest ORs were found in adolescent mothers (1.63; 95% CI 1.25, 2.14), in first born live born infants (1.38; 95% CI 1.09, 1.74) or the fourth born or more (1.28; 95% CI 0.91, 1.80), in unmarried mothers (1.55; 95% CI 1.27, 1.90), in housewives (1.13; 95% CI 0.99, 1.29), and in fathers with manual occupations (1.21; 95% CI 1.04, 1.42). CONCLUSIONS--The results have allowed documentation of the risk of preterm and term LBW in various age and social groups in Spain.
The objectives of this study were to: (1) describe the longitudinal development of sleep-wake patterns of solitary-sleeping infants from 1 to 12 months of age, (2) identify effects on sleep patterns and on self-soothing behaviors of introducing a novel sleep aid, and (3) identify predictive factors of self-soothing at 12 months using a transactional model as a guide.
Eighty infants’ nighttime sleep-wake patterns and associated variables were studied at 5 times across the first year of life using videosomnography and questionnaires.
Sleep-wake state developmental changes, as reported in investigations of infant sleep, were replicated, although a great deal of individual variability in the development of all sleep-related variables was noted. No major effects on sleep or on self-soothing behavior were evident from the introduction of the novel sleep aid. Three variables were identified as significant predictors of self-soothing at 12 months: decreasing amounts of time spent out of crib across the first year, high levels of quiet sleep at birth, and longer parental response times to infant awakenings at 3 months.
These data lend preliminary support for the transactional model and suggest that infant and parental factors interact to influence the development of self-soothing.
Infancy; normal development; parent-child interaction; paediatrics; sleep; temperament; AS: active sleep; AW: wakefulness; BDI: Beck Depression Inventory; GLM: general linear modeling; LSP: longest sleep period; OOC: out of crib; PSOCS: Parenting Sense of Competence Scale; QS: quiet sleep; RSA: representational sleep aid; SC: sham control; SS: self-soothed; TST: total sleep time
In an attempt to foster self-soothing during the night, a novel sleep aid infused with maternal odor was introduced to 4 groups of infants ranging in age from 3 to 12 months. Infants’ use of parent-provided sleep aids also was examined.
Nighttime sleep and waking behaviors were videotaped for 2 consecutive nights on 3 occasions over a 3-month interval. Using all-night video recording, the study examined the infant’s use of a novel sleep aid and parent-provided sleep aids during sleep onset and after nighttime awakenings.
Results indicated that infants of different ages differed in the types of sleep aids used when falling asleep either at the beginning of the night or after awakenings in the middle of the night. More 3-month-olds used their thumbs/fingers/hands, whereas more 6-month-olds used soft objects. The 6-month-olds were most likely to use the novel sleep aid. Almost all of the infants at all 4 ages used some type of object during the night. Intra-individual analyses showed that infants tended to change their pattern of sleep aid use over the 3-month study period.
The data provide evidence that infants during the first year of life use sleep aids frequently and interchangeably rather than a specific favorite object.
Objective We examined longitudinal associations among neonatal and socioeconomic risks, maternal scaffolding behaviors, and 24-month visual-spatial processing and working memory in a sample of 73 toddlers born preterm or low birthweight (PT LBW). Methods Risk data were collected at hospital discharge and dyadic play interactions were observed at 16-months postterm. Abbreviated IQ scores, verbal/nonverbal working memory, and verbal/nonverbal visual-spatial processing data were collected at 24-months postterm. Results Higher attention scaffolding and lower emotion scaffolding during 16-month play were associated with 24-month verbal working memory scores. A joint significance test revealed that maternal attention and emotion scaffolding during 16-month play mediated the relationship between socioeconomic risk and 24-month verbal working memory. Conclusions These findings suggest areas for future research and intervention with children born PT LBW who also experience high socioeconomic risk.
parenting; prematurity; risk
The differential susceptibility to parenting model was examined in relation to toddler self-regulation in a prospective longitudinal study of infants born preterm or low birth weight. We followed 153 mother–infant dyads across five time points between the infant’s Neonatal Intensive Care Unit stay and 24 months postterm. Assessments of infant temperament, quality of early parenting interactions, contextual variables, and toddler effortful control and behavior problems were conducted. Results supported differential susceptibility and dual risk models in addition to documenting main effects of early parenting on children’s emerging self-regulation. Our data suggested that preterm or low birth weight infants who were prone to distress or rated by mothers as more difficult were particularly susceptible to the effects of early negative parenting.
Recent research has implicated infant sleeping body position and bed sharing as risk factors in the sudden infant death syndrome. The sociodemographic associations of infant sleeping body position and location were examined in this study. This showed that the majority (86.4%) of New Zealand parents now place their infants to sleep on their sides. The remainder place their infants supine (1.3%), prone (4.8%), or no particular way (7.5%). In the waking position, 57.9% were usually found on their sides, 18.2% supine, and 6.1% prone. Infant sleeping position showed marked sociodemographic variability. These findings are a marked contrast to previous New Zealand studies which showed a reversed pattern, with most infants put to sleep prone. There were also highly significant sociodemographic differences in the place of sleeping. Overall 12.2% of infants shared a bed, with infants of younger less well educated mothers who were of non-European origin, with a parity of five or more, or unmarried significantly more likely to do so. Infants of unemployed and lower socioeconomic group (Elley-Irving groups 5 and 6) fathers were also more likely to share a parental bed.
Understanding the processes through which interventions work for mothers of premature infants is necessary for the advancement of science and the translation of efficacious interventions into clinical practice settings.
To test a theoretical model examining the processes through which an educational-behavioral intervention program (COPE) influences maternal anxiety and depression 2 months following discharge of their premature infants from the neonatal intensive care unit (NICU).
A secondary analysis was conducted using data from a randomized controlled trial with 246 mothers of low birthweight (LBW) preterm infants who were randomly assigned to COPE or placebo control conditions. Measures included maternal stress in the NICU, maternal anxiety and depression, and maternal beliefs about their infants and their role. Observers blind to study group condition also rated the quality of mother-infant interaction in the NICU.
Structural equation modeling suggested the model tested provided a reasonable fit to the data (χ2 (64 df) = 97.67; p = .004; RMSEA = .046; CFI = .97). Participation in COPE was both directly and indirectly, via associations with increased maternal beliefs and less maternal depression/anxiety in the NICU, related to mothers’ decreased post-hospital depression/anxiety. Participation in the COPE program also was associated with higher mother-infant interaction scores.
Implementation of COPE could lessen post-discharge maternal anxiety and depression, which may improve outcomes for both mothers and preterm infants.
Premature infants; NICU; mothers
Rahman A, Bunn J, Lovel H, Creed F. Association between antenatal depression and low birthweight in a developing country.
There is a high prevalence of depression in south Asian women. We aimed to examine the association between antenatal depression and low birthweight (LBW) in infants in a rural community in Rawalpindi, Pakistan.
A total of 143 physically healthy mothers with ICD-10 depression in the third trimester of pregnancy and 147 non-depressed mothers of similar gestation were followed from birth. Infant weight was measured and information collected on socioeconomic status, maternal body-mass index and sociodemographic factors.
Infants of depressed mothers had lower birthweight (mean 2910 g) than infants of non-depressed mothers (mean 3022 g). The relative risk for LBW (≤2500 g) in infants of depressed mothers was 1.9 (95% CI 1.3–2.9). The association remained significant after adjustment for confounders by multivariate analyses.
Low birthweight is a major public health problem in developing countries. Maternal depression during pregnancy predicts LBW. Interventions aimed at maternal depression may help improve infant outcomes.
mental health; postpartum depression; malnutrition; child development; developing countries
Few objective data are available regarding infants’ night waking behaviors and the development of self-soothing during the first year of life. This cross-sectional study examined 80 infants in one of four age groups (3, 6, 9, or 12 mo) for four nights by using videosomnography to code nighttime awakenings and parent-child interactions. A large degree of variability was observed in parents’ putting the infant to bed awake or asleep and in responding to vocalizations after nighttime awakenings. Most infants woke during the night at all ages observed. Younger infants tended to require parental intervention at night to return to sleep, whereas older infants exhibited a greater proportion of self-soothing after nighttime awakenings. However, even in the 12-month-old group, 50% of infants typically required parental intervention to get back to sleep after waking. Results emphasize the individual and contextual factors that effect the development of self-soothing behavior during the first year of life.
Background: Progress in perinatal medicine has made it possible to increase the survival of very or extremely low birthweight infants. Developmental outcomes of surviving preterm infants have been analysed at the paediatric, neurological, cognitive, and behavioural levels, and a series of perinatal and environmental risk factors have been identified. The threat to the child's survival and invasive medical procedures can be very traumatic for the parents. Few empirical reports have considered post-traumatic stress reactions of the parents as a possible variable affecting a child's outcome. Some studies have described sleeping and eating problems as related to prematurity; these problems are especially critical for the parents.
Objective: To examine the effects of post-traumatic reactions of the parents on sleeping and eating problems of the children.
Design: Fifty families with a premature infant (25–33 gestation weeks) and a control group of 25 families with a full term infant participated in the study. Perinatal risks were evaluated during the hospital stay. Mothers and fathers were interviewed when their children were 18 months old about the child's problems and filled in a perinatal post-traumatic stress disorder questionnaire (PPQ).
Results: The severity of the perinatal risks only partly predicts a child's problems. Independently of the perinatal risks, the intensity of the post-traumatic reactions of the parents is an important predictor of these problems.
Conclusions: These findings suggest that the parental response to premature birth mediates the risks of later adverse outcomes. Preventive intervention should be promoted.
This U.S.A.-based study examined the quantitative and qualitative characteristics of sleep, as well as the role of sleep, in the association of stress with depression, fatigue, and health-related quality of life (H-QOL) among mothers with a low-birth-weight, preterm infant in the neonatal intensive care unit at early postpartum. Fifty-five first-time mothers kept a sleep diary and filled out a battery of questionnaires. The wrist actigraphy method was also applied to collect information on maternal sleep. We tested a path model, with sleep disturbance and depression mediating the effect of stress on health-related well-being. Results showed that the majority of the study participants were stressed, depressed, fatigued, and at risk for poor physical and mental health. Poor sleep quality as perceived by mothers was significantly associated with their stress, fatigue, and poor mental and physical H-QOL. A cascading effect was found in the path model where maternal stress contributed to poor sleep quality and depression, which in turn contributed to poor mental H-QOL. In addition, poor sleep quality was associated with fatigue, which in turn contributed to poor physical and mental H-QOL. The underlying neurobiological mechanisms through which sleep affects the stress–health relation are discussed. The implications of sleep for intervention and prevention are also addressed.
U.S.A.; Low birth weight preterm infant; Stress; Postpartum depression; Sleep; Path analysis
The two-process model is a scheme for the timing of sleep that consists of homeostatic (Process S) and circadian (Process C) variables. The two-process model exhibits abnormal sleep patterns such as internal desynchronization or sleep fragmentation. Early infants with autism often experience sleep difficulties. Large day-by-day changes are found in the sleep onset and waking times in autistic children. Frequent night waking is a prominent property of their sleep. Further, the sleep duration of autistic children is often fragmented. These sleep patterns in infants with autism are not fully understood yet. In the present study, the sleep patterns in autistic children were reproduced by a modified two-process model using nonlinear analysis. A nap term was introduced into the original two-process model to reproduce the sleep patterns in early infants. The nap term and the time course of Process S are mentioned in the present study. Those parameters led to bifurcation of the sleep-wake cycle in the modified two-process model. In a certain range of these parameter sets, a small external noise was amplified, and an irregular sleep-wake cycle appeared. The short duration of sleep led to another irregular sleep onset or waking. Consequently, an irregular sleep-wake cycle appeared in early infantile autism.
Autism; Two-process model; Sleep cycle
Narcolepsy, a disorder characterized by fragmented bouts of sleep and wakefulness during the day and night as well as cataplexy, has been linked in humans and non-human animals to the functional integrity of the orexinergic system. Adult orexin knockout mice and dogs with a mutation of the orexin receptor exhibit symptoms that mirror those seen in narcoleptic humans. As with narcolepsy, infant sleep-wake cycles in humans and rats are highly fragmented, with consolidated bouts of sleep and wakefulness developing gradually. Based on these common features of narcoleptics and infants, we hypothesized that the development of sleep-wake fragmentation in orexin knockout mice would be expressed as a developmental divergence between knockouts and wild-types, with the knockouts lagging behind the wild-types. We tested this hypothesis by recording the sleep-wake patterns of infant orexin knockout and wild-type mice across the first three postnatal weeks. Both knockouts and wild-types exhibited age-dependent, and therefore orexin-independent, quantitative and qualitative changes in sleep-wake patterning. At 3 weeks of age, however, by which time the sleep and wake bouts of the wild-types had consolidated further, the knockouts lagged behind the wild-types and exhibited significantly more bout fragmentation. These findings suggest the possibility that the fragmentation of behavioral states that characterizes narcolepsy in adults reflects reversion back toward the more fragmented sleep-wake patterns that characterize infancy.
orexin; hypocretin; atonia; development; knockout; mouse
This prospective longitudinal study examined emerging effortful control skills at 24- and 36-months postterm in 172 children born preterm (<36 weeks gestation). Infant (neonatal health risks), family (sociodemographic risks) and maternal risk factors (depressive symptoms, anger expressions during play interactions) were assessed at six timepoints across 3 years. Additionally, children’s emerging effortful control skills, cognitive development, and mother-reported behavior and attention problems were assessed at 24- and 36-months. Analyses documented links between effortful control skills, cognitive skills, and concurrent attention problems in children born preterm. The study also found that preterm children’s effortful control skills improved over time. In addition, neonatal health risks, family sociodemographic risks, and angry parenting interactions were associated with less optimal effortful control skills.
ADHD; attention; effortful control; parenting; preterm; risk
There is a general recognition of the role of low birthweight (LBW) as a major determinant of infant mortality rates. Since the rate of LBW has been increasing over the past fifteen years in Japan, we decided to ascertain the risk factors related to it, and also to verify whether or not maternal leisure-time physical activities including sports activities, before pregnancy and during gestation, affected the rate of LBW babies. In our study of the 2,682 questionnaires delivered within a year to the Municipal Health Centers of the three cities chosen for this study, 1,714 questionnaires were analyzed. The results in a univariate analysis showed that maternal height, pre-pregnancy weight, length of gestation, smoking, hospitalization before the 37th week of gestation, a history of LBW, and occupational activities were significantly associated with LBW. In logistic regression analyses, mothers of smaller stature, less pre-pregnancy weight, less length of gestation and mothers who were, furthermore, hospitalized before the 37th week of gestation, smoked, had previously delivered a LBW baby or had experienced stressful events during pregnancy were more likely to have LBW babies. The results showed that maternal leisure-time physical activities before and/or during pregnancy had no bearing on the delivery of a LBW baby.
maternal leisure-time physical activities; low birthweight; risk factors; maternal history of physical activities; pregnancy
Although children born preterm or low birth weight (PT LBW) are more likely to exhibit behavior problems compared to children born at term, developmental and family processes associated with these problems are unclear. We examined trajectories of maternal depressive symptoms in relation to toddler compliance and behavior problems in families with PT LBW infants. A total of 177 infants (93 boys, 84 girls) and their mothers enrolled in the study during the infant’s NICU stay. Data were collected at five time points across 2 years. Assessments of maternal depressive symptoms were conducted at all time points, and toddler compliance and opposition to maternal requests and behavior problems were assessed at 2 years. Toddlers born earlier with more health problems to mothers whose depressive symptoms increased over time exhibited the most opposition to maternal requests during a cleanup task at 24 months, consistent with multiple risk models. Mothers with elevated depression symptoms reported more behavior problems in their toddlers. The study has implications for family-based early intervention programs seeking to identify PT LBW infants at highest risk for problem behaviors.
Singleton infants born after in-vitro fertilization (IVF) are at increased risk for low birth weight (LBW) and/or preterm delivery. We sought to assess if the alteration of the peri-implantation maternal environment due to ovarian stimulation may contribute to increased risk in in vitro fertilization (IVF) births.
The Society of Assisted Reproductive Technology database was used to identify IVF-conceived infants born in the United States between 2004-2006. Associations were assessed in infants born after fresh compared with frozen and thawed embryo transfer in women of similar ovarian responsiveness, in paired analysis of infants born to the same woman following both types of embryo transfer, and in infants born following oocyte donation.
Of 56,792 infants identified, 38,626 and 18,166 were conceived following transfer of fresh and frozen embryos, respectively. In singletons, there was no difference in preterm delivery. However, the odds of overall low birth weight (LBW) (10% vs.7.2%; AOR 1.35, 95% CI 1.20-1.51), LBW at term (2.5% vs. 1.2%; AOR 1.73, 95% CI 1.31-2.29), and preterm LBW (34.1% vs. 23.8%; AOR 1.49, 95% CI 1.24-1.78) were all significantly higher following fresh embryo transfer. In singletons following either fresh or frozen embryo transfer in the same patient, this association was even stronger (LBW: [11.5% vs. 5.6%; AOR 4.66, 95% CI 1.18 – 18.38,). In oocyte donor recipients who do not undergo any ovarian hormonal stimulation for either a fresh or a frozen embryo transfer, no difference in LBW was demonstrated (11.5% vs.11.3%; AOR 0.99, 95% CI 0.82 – 1.18).
The ovarian stimulation-induced maternal environment appears to represent an independent mediator contributing to the risk of LBW, but not preterm delivery, in infants conceived following IVF.
Increasing paternal birthweight has been associated with increased risk of fathering a preterm infant, causing speculation that a fetus programmed to grow rapidly can trigger preterm labor.
Pregnancies occurring from 1974 to 1989 among women themselves born in the Danish Perinatal Study (1959–61) were identified through the Population Register; obstetrical records were abstracted. Paternal birthweight was obtained by linking Personal Identification Numbers of the fathers to archived midwifery records.
Paternal birthweight was not associated with preterm infants overall. However, there was a significant interaction between paternal and maternal birthweights (p=0.003). When the mother weighed <3 kg at birth, increasing paternal birthweight was associated with increased occurrence of preterm birth (p for trend=0.02); paternal birthweight was unassociated with preterm birth for mothers weighing ≥3 kg at birth (p=0.34).
When the mother was born small, increasing paternal birthweight was associated with increased risk of preterm birth, suggesting that a fetus growing faster than its mother can accommodate might trigger preterm birth.
Birthweight; genetics; paternal effects
Our aim was to measure the correlation between fetal electrocardiographic (FECG) recordings of low-risk pregnancies and polysomnographic (PSG) study parameters in low-risk infants born at term as a measurement of perinatal sleep-development continuity.
We designed a short, prospective, observational follow-up of physiologic parameters between fetuses and newborns. We studied 10 fetuses from low-risk pregnant female out-patients and the same subjects as low-risk newborns delivered at term. Fetal state (FS) was defined in FECG recordings reassembling the following: fetal state I (quiet sleep or QS); fetal state II (active sleep or AS); fetal state III (quiet waking), and fetal state IV (active waking). Percentages of AS, QS, and wakefulness in PSG studies of newborns were also determined.
Comparisons of FS I with QS showed a significant reduction in QS, while comparison of FS II with AS showed significant reduction in AS. Negative correlations were found between FS I with QS, and FS II with AS. Number of cycles in FECG recordings and PSG sleep cycles also demonstrated significant correlation.
In conclusion our data showed partial but significant sleep function continuity from fetal to neonatal period.
Sleep development; Fetuses; Newborns; Fetal electrocardiographic recordings; Polysomnography.
Studies in adult mammals (rats, cats, mice, and humans) have revealed a surprising regularity in the duration of sleep and wake bouts. In particular, wake bout durations exhibit a power-law distribution whereas sleep bout durations exhibit an exponential distribution. Moreover, in rodents, sleep bouts exhibit an exponential distribution at all ages examined, whereas wake bout durations exhibit exponential distributions early in ontogeny with a clear power-law emerging only at the older ages. Thus, the data examined thus far suggests a similar developmental trajectory for a wide range of mammals which in turn may offer a novel metric to directly compare human and animal sleep–wake data. Therefore, we tested the generalizability of these findings by examining the distributions of sleep and wake bouts during the night in a healthy human sample – from premature infants to 70-year-olds. We find that sleep bouts elongate over the first years. At the same time wake bouts shorten but elongate again with increasing age. Moreover, sleep bout durations exhibit exponential distributions at all ages tested, except for the youngest (premature infants). Wake bouts exhibit a power-law distribution – but only during a restricted time window during adulthood. We conclude that the developmental trajectory of human sleep–wake cycles does not map well onto those of rodents; however, the method of characterizing sleep–wake cycles, using bout distribution, holds great promise for classifying sleep, its disorders, and tracking its developmental milestones across the lifespan in humans.
sleep; wakefulness; ontogeny; sleep–wake cycles
This study examines whether an integrated behavioral intervention with proven efficacy in reducing psycho-behavioral risks (smoking, environmental tobacco smoke exposure (ETSE), depression, and intimate partner violence (IPV)) in African-Americans is associated with improved pregnancy outcomes
A randomized controlled trial targeting risks during pregnancy was conducted in the District of Columbia. African-American women were recruited if reporting at least one of the risks mentioned above. Randomization to intervention or usual care was site and risk specific. Sociodemographic, health risk and pregnancy outcome data were collected. Data on 819 women, and their singleton live born infants were analyzed using an intent-to-treat approach. Bivariate analyses preceded a reduced logistical model approach to elucidate the effect of the intervention on the reduction of prematurity and low birth weight.
The incidence of low birthweight LBW was 12% and very low birthweight VLBW was 1.6%. Multivariate logistic regression results showed that depression was associated with LBW (OR=1.71, 95%CI=1.12–2.62). IPV was associated with PTB and VPTB (OR 1.64, 95%CI=1.07–2.51, OR=2.94, 95%CI=1.40–6.16, respectively). The occurrence of VPTB was significantly reduced in the intervention compared to the usual care group (OR=0.42, 95%CI=0.19–0.93).
Our study confirms the significant associations between multiple psycho-behavioral risks and poor pregnancy outcomes, including LBW and PTB. Our behavioral intervention with demonstrated efficacy in addressing multiple risk factors simultaneously reduced VPTB within an urban minority population.
African-American; birth weight; pregnancy; gestational age