Cross-cultural disparities of subjective sleep parameters and their age-related trends over the first three years of human life: A systematic review and meta-analysis.

Changes in nighttime sleep consolidation and daytime discontinuation have been observed in early life. Yet information about societal or cultural factors remains scant for implementing sleep recommendations. We aimed to provide pooled estimates of subjective sleep duration, number of nightwakings and sleep timing; to describe their age-related trends; and to determine potential cross-cultural disparities between predominantly-Asian (PA) and predominantly-Caucasian (PC) regions during the first three years of life. We performed this review according to the PRISMA guidelines. Overall, 102 studies with 167,886 children aged 0-3 y from 26 different countries/regions were included. Compared to PC regions, PA toddlers had shorter sleep duration and more frequent nightwakings. When PC regions were further divided into Pacific Rim and Europe, differences were much more evident between PA and Pacific Rim for all nighttime sleep parameters. Trends of nighttime sleep duration and bedtime for PC regions showed rapid changes over the first 3-6 mo before stabilizing to a plateau, whereas a different change was found for PA regions. In conclusion, an apparent cross-cultural disparity of the subjective sleep parameters already exists in early childhood. Improved operationalization of sleep parameters and more objective evidence are needed to establish cultural-sensitive recommendations this early in life.

Relationship between Duration of Sleep and Hypertension in Adults: A Meta-Analysis.

OBJECTIVES: Epidemiologic studies have shown that chronic short sleep may be associated with the development of hypertension; however, the results are controversial. This meta-analysis was conducted to determine whether the duration of sleep is associated with hypertension. METHODS: Reference databases (PubMed, EmBase, the Cochrane Library, Chinese Biological Medicine database) were searched for studies related to sleep duration and hypertension. Sleep duration categories (≤ 5 h, 6 h, 7 h, 8 h, ≥ 9 h) and prevalence or incidence of hypertension in each sleep category were extracted. A general analysis and subgroup analyses stratified by gender, age, study design, and different definitions of sleep duration were conducted to evaluate the relationship between sleep duration and hypertension. RESULTS: Thirteen articles out of a total of 1,628 articles involving 347,759 participants met the inclusion criteria. A U-shaped change in pooled odds ratios (ORs) for hypertension due to the change of sleep duration was observed. The unadjusted OR for hypertension of individuals who slept ≤ 5 h vs. 7 h was 1.61, 95% CI = 1.28-2.02; those who slept ≥ 9 h vs. 7 h was 1.29, 95% CI = 0.97-1.71. The pooled ORs were still significant after adjusted by age and gender. Women deprived of sleep (sleep time ≤ 5 h vs. 7 h, OR = 1.68, 95% CI = 1.39-2.03) had a higher risk of hypertension than men (OR = 1.30, 95% CI = 0.93-1.83). CONCLUSION: Excessively longer and shorter periods of sleep may both be risk factors for high blood pressure; these associations are stronger in women than men.

Somatic growth of lean children: the potential role of sleep.

BACKGROUND: Despite the current obesity pandemic, childhood malnutrition remains an urgent, public health concern. Similar to the obesity pandemic, childhood malnutrition is influenced by genetic and a number of social, environmental and biological factors. In this study, we investigated the association between sleep duration and somatic growth in lean children. METHODS: A stratified, randomly clustered sampling design was used to select fifth grade students from 10 primary schools in Shanghai. Based on a body mass index below the 15th percentile a subsample of 143 lean children aged 10-11 years old was defined. Sleep duration and other potential confounders were surveyed through parental or self-report questionnaires. Body measurements were collected and used to calculate the Z score of weight, height, body mass index as well as body fat percentage. RESULTS: Compared with children who slept <9 hours, those who slept for ≥10 hours grew taller and gained more weight after adjusting for confounding factors. When children slept 9-10 hours, they had significantly higher Z score of weight and body mass index. CONCLUSIONS: Prolonged sleep not only benefits weight gain but also improves height in lean children. Our findings might provide important public health advice such that prolonged sleep may be an effective modifier of nutritional problems in childhood.

The relation among sleep duration, homework burden, and sleep hygiene in chinese school-aged children.

Insufficient sleep in school-aged children is common in modern society, with homework burden being a potential risk factor. The aim of this article is to explore the effect of sleep hygiene on the association between homework and sleep duration. Children filled out the Chinese version of the Adolescent Sleep Hygiene Scale, and parents filled out a sociodemographic questionnaire. The final sample included 363 boys and 371 girls with a mean age of 10.82 ± 0.38 years. Children with more homework went to bed later and slept less. Better sleep hygiene was associated with earlier bedtimes and longer sleep duration. Findings suggest that homework burden had a larger effect on sleep duration than sleep hygiene. Fifth-grade children in Shanghai have an excessive homework burden, which overwrites the benefit of sleep hygiene on sleep duration.

[The association of sleep hygiene and sleep quality among school-age children].

OBJECTIVE: To study the association between sleep hygiene and sleep duration and quality among school-age children, and to explore the risk factors related to poor sleep hygiene. METHODS: Totally 2019 grade-five children were sampled by stratified cluster random sampling from 10 primary schools in Shanghai, during November and December 2009. Questionnaires were used to investigate children and their parents. Adolescent Sleep Hygiene Scale (ASHS) was used to inquiry sleep hygiene of children; Children Sleep Habits Questionnaire (CSHQ) was used to assess their sleep duration and quality; Family and Social Environment Questionnaire was used to collect demographic and socio-economic information. T-test, one-way ANOVA and multiple linear regression model were established to identify the risk factors for sleep hygiene. RESULTS: The age of subjects was (10.81 ± 0.38) years old, 49.0% (989/2019) were boys. The ASHS total score was 125.43 ± 15.17, girls with better sleep hygiene than boys (127.05 ± 14.41 vs 123.74 ± 15.75, P < 0.05). The sleep duration was (9.47 ± 0.58)h/d, children slept less than 9 h/d had lower ASHS total score than those slept 9 - 10 h/d or over 10 h/d (121.69 ± 16.09 vs 126.17 ± 14.62 vs 126.50 ± 15.36, P < 0.05). Children with poor sleep quality had worse sleep hygiene than those with good sleep quality (121.00 ± 15.84 vs 128.36 ± 13.92, P < 0.05). Children with television set in bedroom had lower ASHS total score than the others (122.40 ± 15.76 vs 126.74 ± 14.66, P < 0.05). Children from single parent family had lower ASHS total score (117.90 ± 16.80 vs 125.94 ± 14.89, P < 0.05). Children whose father had irregular sleep or wake pattern had lower ASHS total score (122.65 ± 15.30 vs 125.89 ± 14.90 vs 127.79 ± 14.71, P < 0.05). The regression model confirmed that existence of television set in children's bedroom, single-parent family and father's irregular sleep pattern were the risk factors of poor sleep hygiene. CONCLUSION: Sleep hygiene was closely associated with sleep duration and quality among school-age children. Children with television set in bedroom, male, from single parent family and whose father had irregular sleep or wake pattern had worse sleep quality.