Preterm toddlers have low nighttime sleep quality and high daytime activity.

A number of studies have been made on the sleep characteristics of children born preterm in an attempt to develop methods to address the sleep problems commonly observed among such children. However, the reported sleep characteristics from these studies vary depending on the observation methods used, i.e., actigraphy, polysomnography and questionnaire. In the current study, to obtain reliable data on the sleep characteristics of preterm-born children, we investigated the difference in sleep properties between 97 preterm and 97 term toddlers of approximately 1.5 years of age using actigraphy. Actigraphy units were attached to the toddlers' waists with an adjustable elastic belt for 7 consecutive days, and a child sleep diary was completed by their parents. In the study, we found that preterm toddlers had more nocturnal awakenings and more daytime activity, suggesting that preterm-born children may have a different process of sleep development in their early development.

Sleep maturation influences cognitive development of preterm toddlers.

Our recent study on full-term toddlers demonstrated that daytime nap properties affect the distribution ratio between nap and nighttime sleep duration in total sleep time but does not affect the overall total amount of daily sleep time. However, there is still no clear scientific consensus as to whether the ratio between naps and nighttime sleep or just daily total sleep duration itself is more important for healthy child development. In the current study, to gain an answer to this question, we examined the relationship between the sleep properties and the cognitive development of toddlers born prematurely using actigraphy and the Kyoto scale of psychological development (KSPD) test. 101 premature toddlers of approximately 1.5 years of age were recruited for the study. Actigraphy units were attached to their waist with an adjustable elastic belt for 7 consecutive days and a child sleep diary was completed by their parents. In the study, we found no significant correlation between either nap or nighttime sleep duration and cognitive development of the preterm toddlers. In contrast, we found that stable daily wake time was significantly associated with better cognitive development, suggesting that sleep regulation may contribute to the brain maturation of preterm toddlers.

Daytime nap and nighttime breastfeeding are associated with toddlers' nighttime sleep.

The purpose of the present study is to examine the association between toddlers' sleep arrangements and their nighttime sleep duration and other sleep variables. For this investigation, we performed a study in which child activity and sleep levels were recorded using actigraphy. The parents of 1.5-year-old toddlers (n = 106) were asked to attach an actigraphy unit to their child's waist with an adjustable elastic belt and complete a sleep diary for 7 consecutive days. Questionnaires were used to assess the sleep arrangements of the toddlers. There was a significant negative correlation between nap duration and nighttime sleep duration, suggesting that longer nap sleep induces shorter nighttime sleep duration. Among the sleep arrangements, such as nighttime breastfeeding or co-sleeping, only nighttime breastfeeding predicted shorter nighttime sleep duration. Our findings indicate that shorter naps induce a longer nighttime sleep in 1.5-year-old toddlers while nighttime breastfeeding decreases their nighttime sleep duration.

Postural change for supine position does not disturb toddlers' nap.

This study examined whether forced postural change from prone to supine during toddlers' nap, a preventative measure taken in Japan for sudden unexplained death in childhood (SUDC), disturbs toddlers' sleep. When the "Back to Sleep" campaign (BSC) was introduced to Japan in 1996, its recommendations were also applied to infants aged 1 year old and over with the expectation that the BSC recommendations may also contribute to a decrease in the occurrence rate of SUDC. Since then, Japanese nurseries have routinely conducted sleeping position checks and positional adjustments of toddlers every 5-10 min during naps. A total of 52 toddlers (age 18.4 ± 3.3 months, means ± SD) were continuously monitored for 8 h during daytime at nursery schools for wake-sleep status and body position (prone, supine and lateral) with actigraphs and 3-orthogonal-axis accelerometers. Out of the 52 toddlers, 24 toddlers adopted prone positions during naps, which were adjusted by nursery staff back to supine. When nursery staff manually changed the toddlers position from prone to supine, the toddlers either did not wake or woke only briefly (3.1 ± 4.9 min) and returned to sleep soon after the positional change. Our study indicates that manual change of toddlers' sleeping position from prone to supine, a potential SUDC prevention method, does not disturb toddlers' sleep during their naps.

Combined effects of body position and sleep status on the cardiorespiratory stability of near-term infants.

The purpose of this study was to determine the effects of body position (prone, supine and lateral) together with sleep status (wake and sleep) on the cardiorespiratory stability of near-term infants. A total of 53 infants (gestational age at birth 33.2 ± 3.5 weeks; birth weight 1,682 ± 521 g; gestational age at recording 38.6 ± 2.1 weeks; weight at recording: 2,273 ± 393 g) were monitored for 24 hours for clinically significant apnea (>15 seconds), bradycardia (<100 bpm), and oxygen desaturation (SpO2 < 90%) in alternating body positions (prone, supine and lateral) by cardiorespiratory monitors and 3-orthogonal-axis accelerometers. Sleep status of the infants was also continuously monitored by actigraphs. No apnea was observed. During wake, severe bradycardia was most frequently observed in the lateral position while, during sleep, severe bradycardia was most frequently observed in the supine position. Desaturation was most frequently observed in the supine and lateral positions during both wake and sleep. Our study suggests that the cardiorespiratory stability of infants is significantly compromised by both body position and sleep status. During both wake and sleep, prone position induces the most stable cardiorespiratory functions of near-term infants.

Daytime nap controls toddlers' nighttime sleep.

Previous studies have demonstrated that afternoon naps can have a negative effect on subsequent nighttime sleep in children. These studies have mainly been based on sleep questionnaires completed by parents. To investigate the effect of napping on such aspects of sleep quality, we performed a study in which child activity and sleep levels were recorded using actigraphy. The parents were asked to attach actigraphy units to their child's waist by an adjustable elastic belt and complete a sleep diary for 7 consecutive days. 50 healthy young toddlers of approximately 1.5 years of age were recruited. There was a significant negative correlation between nap duration and both nighttime sleep duration and sleep onset time, suggesting that long nap sleep induces short nighttime sleep duration and late sleep onset time. We also found a significant negative correlation between nap timing and nighttime sleep duration and also a significant positive correlation between nap timing and sleep onset time, suggesting that naps in the late afternoon also lead to short nighttime sleep duration and late sleep onset. Our findings suggest that duration-controlled naps starting early in the afternoon can induce a longer nighttime sleep in full-term infants of approximately 1.5 years of age.

Influence of light exposure at nighttime on sleep development and body growth of preterm infants.

Previous studies have demonstrated that a light-dark cycle has promoted better sleep development and weight gain in preterm infants than constant light or constant darkness. However, it was unknown whether brief light exposure at night for medical treatment and nursing care would compromise the benefits brought about by such a light-dark cycle. To examine such possibility, we developed a special red LED light with a wavelength of >675 nm which preterm infants cannot perceive. Preterm infants born at <36 weeks' gestational age were randomly assigned for periodic exposure to either white or red LED light at night in a light-dark cycle after transfer from the Neonatal Intensive Care Unit to the Growing Care Unit, used for supporting infants as they mature. Activity, nighttime crying and body weight were continuously monitored from enrolment until discharge. No significant difference in rest-activity patterns, nighttime crying, or weight gain was observed between control and experimental groups. The data indicate that nursing care conducted at 3 to 4-hour intervals exposing infants to light for <15 minutes does not prevent the infants from developing circadian rest-activity patterns, or proper body growth as long as the infants are exposed to regular light-dark cycles.

Artificial oxygen carriers rescue placental hypoxia and improve fetal development in the rat pre-eclampsia model.

Pre-eclampsia affects approximately 5% of all pregnant women and remains a major cause of maternal and fetal morbidity and mortality. The hypertension associated with pre-eclampsia develops during pregnancy and remits after delivery, suggesting that the placenta is the most likely origin of this disease. The pathophysiology involves insufficient trophoblast invasion, resulting in incomplete narrow placental spiral artery remodeling. Placental insufficiency, which limits the maternal-fetal exchange of gas and nutrients, leads to fetal intrauterine growth restriction. In this study, in our attempt to develop a new therapy for pre-eclampsia, we directly rescued placental and fetal hypoxia with nano-scale size artificial oxygen carriers (hemoglobin vesicles). The present study is the first to demonstrate that artificial oxygen carriers successfully treat placental hypoxia, decrease maternal plasma levels of anti-angiogenic proteins and ameliorate fetal growth restriction in the pre-eclampsia rat model.

Evaluating mortality and disease severity in congenital diaphragmatic hernia using the McGoon and pulmonary artery indices.

PURPOSE: Lung hypoplasia is associated with mortality in congenital diaphragmatic hernia (CDH). However, the association between lung hypoplasia and disease severity is unclear. Early prediction of disease severity would provide parents with more precise information about the anticipated course of treatment, minimize treatment disruption, and maximize the efficient management of patients with CDH. We aimed at identifying the relationship between McGoon index (MGI) and pulmonary artery index (PAI) scores and disease severity among infants with CDH. METHODS: We retrospectively reviewed the medical records of 19 high-risk patients with CDH born between January 2006 and December 2007. McGoon index and PAI scores were determined on admission. We evaluated statistically the relationship between these scores and variables representing severity as follows: number of vasodilators, use of inhaled nitric oxide (iNO), closed method of diaphragm, duration of intubation, duration of hospitalization, and use of home oxygen therapy. Statistical significance was P < .05. RESULTS: Overall median MGI and PAI scores were 1.40 and 108, respectively; scores for nonsurvivors were significantly (P < .05 and P < .01, respectively) lower than those for survivors. Among survivors, PAI scores were significantly (P < .05) lower in infants requiring iNO than in infants not requiring iNO and patch repair. The PAI scores were significantly correlated with the number of vasodilators (r = -0.789; P < .01) and duration of intubation (r = -0.610; P < .05). CONCLUSIONS: McGoon index (cutoff value, 1.31) and PAI (cutoff value, 90) are reliable indices for predicting mortality in CDH. Pulmonary artery index appears to be more useful than MGI for predicting disease severity among survivors.