Objective To examine sleep problems and fatigue and their associations with cognitive performance in Chinese kindergarten children. Study design A cross-sectional analysis of baseline data from Jintan Child Cohort Study was conducted, which includes a cohort of 1,656 kindergarten children in Jintan City, Jiangsu Province, China. The sample used in the current study consisted of 1,385 children (44.8% girls, mean age 5.72 (SD=0.42) years) for whom data on sleep problems or cognitive performance were available. Child Behavior Checklist was used to measure child sleep problems and fatigue, and Wechsler Preschool and Primary Scale of Intelligence – Revised was used to assess child intelligence quotient (IQ). Results Sleep problems were prevalent, ranging from 8.9% for difficulty maintaining sleep (DMS) to 70.5% for unwilling to sleep alone. Other reported sleep problems were difficulty initiating sleep (39.4%), nightmares (31.6%), sleep talking (28%), sleeping less (24.7%), and sleep resistance (23.4%). Fatigue was also prevalent, with 29.6% of children reported to be overtired and 12.6% lack of energy. Children with DMS, sleep talking, sleep resistance, or nightmares scored 2-3 points lower in full IQ than children without sleep problems. Children reported to have fatigue scored 3-6 points lower in full IQ than those children without fatigue. Conclusions Sleep problems and fatigue are prevalent in Chinese kindergarten children. Furthermore, sleep problems and fatigue are associated with poor cognitive performance.

Background Despite the body of literature that links anemia with poorer cognition in children and the evidence that the severity of the effects of anemia on children’s cognition vary in different populations, few studies have investigated the effects of anemia on the cognitive development of Chinese children. Study Design This longitudinal cohort includes 171 children from a developing region of China. Hemoglobin and iron levels were taken when the children were 4 years old. At age 6, the children’s cognition was tested with Chinese WPPSI. Psychosocial information was also used in analyses. Results Results showed that the children who had low Hb levels had significantly lower scores in PIQ, but not VIQ. Although blood Fe levels were not shown to moderate the link between hemoglobin levels and IQ, we found children who performed the best on IQ tests exhibited low iron levels concurrent with high hemoglobin levels, whereas the group who performed the worst exhibited high iron but low hemoglobin levels. We also found that psychosocial adversity did not differ significantly between children who had normal or low hemoglobin levels, although the effect of hemoglobin on PIQ became only suggestive after controlling for psychosocial adversity, therefore the relationship is not causal but only a suggestive association. Conclusion Our findings are in agreement with literature on the negative effects of anemia on children’s cognition and point to the possibility that the portions of the brain associated with PIQ components are particularly affected by low Hb during crucial periods of development.

This study examined the prevalence of sleep disordered breathing (SDB) symptoms and their associations with daytime sleepiness, emotional problems, and school performance in Chinese children. Participants included 3,979 children (10.99 ± 0.99 years old) from four elementary schools in Jintan City, Jiangsu Province, China. Children completed a self-administered questionnaire on sleep behavior and emotional problems, while parents completed the Child Sleep Habit Questionnaire (CSHQ). SDB symptoms included 3 items: loud snoring, stopped breathing, and snorting/ gasping during sleep. Teachers rated the children's school performance. The prevalence rates of parent- and self-reported SDB symptoms were 17.2% and 10.1% for “sometimes” and 8.9% and 5.6% for “usually”. SDB symptoms, more prevalent in boys than in girls, increased the risks for depression, loneliness, and poor school performance. Daytime sleepiness mediated the relationship between SDB symptoms and depression, loneliness, and poor school performance. This study suggests the importance of early screening and intervention of SDB and daytime sleepiness in child behavioral and cognitive development.

The China Jintan Child Cohort study began in 2004 with 1656 pre-school participants and a research focus on studying the impact of environmental exposures, such as lead, on children's neurobehavioural outcomes. This population cohort now includes around 1000 of the original participants, who have been assessed three times over a period of 10 years. Since the original IJE cohort profile publication in 2010, participants have experienced a critical developmental transition from pre-school to school age and then adolescence. The study has also witnessed an increase in breadth and depth of data collection from the original aim of risk assessment. This cohort has added new directions to investigate the mechanisms and protective factors for the relationship between early health factors and child physical and mental health outcomes, with an emphasis on neurobehavioural consequences. The study now encompasses 11 domains, composed of repeated measures of the original variables and new domains of biomarkers, sleep, psychophysiology, neurocognition, personality, peer relationship, mindfulness and family dynamics. Depth of evaluation has increased from parent/teacher report to self/peer report and intergenerational family report. Consequently, the cohort has additional directions to include: (i) classmates of the original cohort participants for peer relationship assessment; and (ii) parental and grandparental measures to assess personality and dynamics within families. We welcome interest in our study and ask investigators to contact the corresponding author for additional information on data acquisition.

Trace elements such as copper are essential micronutrients. Traditionally, copper has been studied in the context of micronutrient deficiencies. Recent studies in both animals and humans, however, have revealed that elevated blood copper can also have adverse effects on cognitive function since free copper can cross the blood-brain barrier and subsequently impose oxidative stress to neuronal cells. However, most of these human studies were conducted in adult populations with and without cognitive decline, and there are few studies on the effect of excess copper on cognitive function in children. This project seeks to look at the effects of elevated copper levels on cognitive development in a population of school age children (ages 10–14 years with mean age of 12.03 years and standard deviation (SD) of 0.44) from Jintan, China. Briefly, serum copper levels and working memory test scores were collected from a sample of 826 children with a mean serum copper level of 98.10 (SD 0.75). Copper level was considered as a categorical variable (taking the first group as those with as ≤84.3 μg/dL, the second group as >84.3 and ≤110.4 μg/dL, and the third group as >110.4 μg/dL with the cut-off values defined by the first and third quartiles of the sample). Results showed a significant association between high copper levels (>110.4 μg/dL) and poorer working memory in boys but this association was not seen in lower copper levels in either sex. These results suggests that in school age children, like in adults, elevated copper levels have the potential to adversely affect cognition.