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One of the most important age ranges for children to develop good sleeping habits, behaviors, and lifestyles is 6–17 years of age. During these years, sleep has significantly impacted many aspects of learning, daily life, and health status (1). Studies from 2010–2012 showed that the proportion of children and adolescents in China who do not get the recommended sufficient sleep was 69.8% (2). With only a few subsequent studies reporting on the sleep status of children and adolescents nationwide, knowledge of this field has been limited in recent years (2–5). This study used data from the China Nutrition and Health Surveillance of Children and Lactating Mothers in 2016–2017 to assess the average sleep duration, sleep patterns, and distribution of total sleep duration per 24 hours and naptime among children and adolescents aged 6–17 years in China. It is the latest data inferred from the surveillance program. The results show that approximately half of adolescents aged 13–17 years do not get the recommended amount of sleep on school days, and more than half oversleep on weekends. Targeted interventions are needed to make parents and children, especially older age groups and those in urban areas, aware of the importance of getting sufficient sleep and developing good sleeping habits.
The data in this study came from the China Nutrition and Health Surveillance of Children and Lactating Mothers in 2016–2017, which uses a multi-stage stratified cluster randomized sampling method. The method classifies all county-level administrative units in the mainland of China into four categories: big cities, medium and small cities, ordinary rural areas, and rural areas with lower economic development. These four areas were classified according to their economic and social development (6). First, a total of 275 county-level units were selected as surveillance points from the four categories. Second, two townships/subdistricts were selected from each surveillance point, with one primary school and one junior high school selected from each township/subdistrict. In addition, one high school was selected from each surveillance point, and one class was selected from each grade, with 28 students from each class being surveyed. The sample size was calculated using the 2013 overweight rate of 4.5% for children and adolescents aged 7–17 years as the calculation marker for determining sample size and taking into account a non-response rate of 10%. After data cleaning, a total of 74,246 valid samples of children aged 6–17 years were obtained. A total of 67,657 participants were included in this analysis, while 6,589 participants were excluded as a result of missing basic information variables or extreme values. The study was approved by the Ethical Committee of the Chinese Center for Disease Control and Prevention. All participants provided written informed consent signed by their parents.
The China Nutrition and Health Surveillance of Children and Lactating Mothers included questionnaires, medical examinations, dietary surveys, and laboratory tests. A self-designed questionnaire, with consultation and validation from experts, was used to collect basic information from respondents during face-to-face interviews with trained and qualified interviewers. The questionnaire collected information including demographic characteristics (i.e., gender, age, region, etc.) and sleep behaviors. Regions were divided based on physical geography and expert research, including North China (Beijing Municipality, Tianjin Municipality, Hebei Province, Shanxi Province, Inner Mongolia Autonomous Region), Northeast China (Heilongjiang Province, Jilin Province, Liaoning Province), East China (Shanghai Municipality, Jiangsu Province, Zhejiang Province, Shandong Province, Anhui Province, Jiangxi Province, Fujian Province, Taiwan, China), Central China (Hubei Province, Hunan Province, Henan Province), South China (Guangdong Province, Guangxi Zhuang Autonomous Region, Hainan Province, Hong Kong Special Administrative Region, Macao Special Administrative Region), Southwest China [Sichuan Province, Chongqing Municipality, Guizhou Province, Yunnan Province, Xizang (Tibet) Autonomous Region], and Northwest China (Shaanxi Province, Gansu Province, Xinjiang Uygur Autonomous Region, Qinghai Province, Ningxia Hui Autonomous Region). Left-behind children are defined as those with at least one parent currently working and living away from home for six or more months by the time of the survey, resulting in the child living alone without parental supervision. The wake-up time and bedtime were obtained by asking parents, “what time does your child usually get up in the morning and go to bed at night?” Naptime durations were obtained by asking parents, “how long does your child usually sleep during the day?” Sleep duration was calculated from the wake-up time and bedtime, while total sleep duration per 24 hours was calculated by the addition of sleep duration and naptime. According to a consensus statement by the American Academy of Sleep Medicine (7), the recommended amount of sleep is 9–12 hours for children aged 6–12 years and 8–10 hours for adolescents aged 13–18 years per 24 hours regularly. Insufficient sleep was defined as <9 hours for children and <8 hours for adolescents.
All statistical analyses were performed using the software SAS (version 9.4, SAS Institute Inc., Cary, USA), and P<0.05 was statistically significant. The data were adjusted for complex sample weights to ensure that the findings were nationally representative of children and adolescents; each observation was weighted by two components, namely sample weights, and ex-post weights, which were based on urban-rural, age- and sex-specific population data from the Sixth Population Census 2010 published by the National Bureau of Statistics. Means were calculated using the survey means process. t-tests and ANOVA were conducted to test for group differences in means, and Rao-Scott chi-squared tests were conducted for prevalence.
A total of 67,657 Chinese children and adolescents aged 6–17 years were included in the data analysis, including 33,652 males and 34,005 females. Table 1 describes the baseline characteristics of the participants and the total sleep duration per 24 hours for children and adolescents with different characteristics. Their average total sleep duration per 24 hours was 9.10 [standard deviation (SD): 1.30] hours on school days and 10.31 (SD: 1.42) hours on weekends. The total sleep duration per 24 hours decreased with age and was shortest in the Northeast and longest in the Southwest. Boys slept longer than girls on school days (9.15 hours versus 9.04 hours, P<0.0001), but the opposite occurred on weekends (10.23 hours versus 10.40 hours, P<0.0001). Children and adolescents in rural areas slept longer than those in urban areas, especially on school days (9.29 hours versus 8.87 hours, P<0.0001). The sleep duration composition of children and adolescents aged 6–12 years and 13–17 years is shown in Figure 1. The proportion of children aged 6–12 years meeting the recommended amount of sleep was 84.8% on school days and 80.7% on weekends. Among adolescents aged 13–17 years, the proportions were 54.7% and 37.0% on school days and weekends, respectively.
Characteristics Total (%) School-days sleeptime, [hours (SD)] P value Weekends sleeptime, [hours (SD)] P value Total 67,657 (100) 9.10±1.30 10.31±1.42 Age group (years) <0.0001 <0.0001 6– 17,720 (26.19) 10.02±0.80 10.63±1.09 9– 20,601 (30.45) 9.77±0.95 10.50±1.24 12– 16,515 (24.41) 8.95±1.10 10.29±1.44 15–17 12,821 (18.95) 7.89±0.98 9.90±1.67 Sex <0.0001 <0.0001 Male 33,652 (49.74) 9.15±1.27 10.23±1.42 Female 34,005 (50.26) 9.04±1.33 10.40±1.43 Area <0.0001 <0.0001 Urban 31,896 (47.14) 8.87±1.26 10.25±1.46 Rural 35,761 (52.86) 9.29±1.30 10.35±1.39 Region* <0.0001 <0.0001 North China 10,114 (14.95) 8.89±1.25 10.12±1.38 Northeast China 5,367 (7.93) 8.77±1.29 10.04±1.50 East China 17,203 (25.43) 9.07±1.27 10.28±1.42 Central China 9,063 (13.40) 9.28±1.34 10.36±1.35 South China 7,041 (10.41) 8.93±1.23 10.13±1.50 Southwest China 10,883 (16.09) 9.36±1.30 10.51±1.40 Northwest China 7,986 (11.80) 8.94±1.32 10.46±1.41 Primary caregiver <0.0001 <0.0001 Father/mother 53,744 (79.44) 9.02±1.30 10.29±1.44 Grandparents 12,416 (18.35) 9.44±1.23 10.39±1.33 Others 1,497 (2.21) 8.92±1.23 10.27±1.61 Living in the school <0.0001 <0.0001 Yes 18,532 (27.39) 8.61±1.35 10.08±1.59 No 49,125 (72.61) 9.31±1.21 10.41±1.33 Left-behind children <0.0001 <0.0001 Yes 13,547 (20.02) 9.32±1.27 10.39±1.39 No 54,110 (79.98) 9.03±1.30 10.28±1.43 Abbreviation: SD=standard deviation.
* Regions were divided based on physical geography and expert research, including North China (Beijing Municipality, Tianjin Municipality, Hebei Province, Shanxi Province, Inner Mongolia Autonomous Region), Northeast China (Heilongjiang Province, Jilin Province, Liaoning Province), East China (Shanghai Municipality, Jiangsu Province, Zhejiang Province, Shandong Province, Anhui Province, Jiangxi Province, Fujian Province, Taiwan, China), Central China (Hubei Province, Hunan Province, Henan Province), South China (Guangdong Province, Guangxi Zhuang Autonomous Region, Hainan Province, Hong Kong Special Administrative Region, Macao Special Administrative Region), Southwest China [Sichuan Province, Chongqing Municipality, Guizhou Province, Yunnan Province, Xizang (Tibet) Autonomous Region], and Northwest China (Shaanxi Province, Gansu Province, Xinjiang Uygur Autonomous Region, Qinghai Province, Ningxia Hui Autonomous Region).Table 1. Total sleep duration per 24-hour for children and adolescents with different characteristics — China, 2016–2017.
Figure 1.Sleep duration composition of children and adolescents aged 6–17 years — China, 2016–2017.
Overall, children and adolescents aged 6–17 years had an average wake-up time of 6:22 and 7:57, an average bedtime of 21:43 and 22:08, and an average nighttime sleep duration of 8.64 and 9.81 hours on school days and weekends, respectively. With increasing age, the wake-up time on school days is earlier from 6:06 to 6:40, bedtime is later from 20:56 to 22:56, and sleep duration at night is shorter from 9.73 to 7.16 hours. On weekends, the wake-up time is around 8:00, and bedtime is generally about half an hour later than on school days. Urban children slept later and less than rural children (Table 2). Figure 2 shows the distribution of naptime among Chinese children aged 6–17 years, classifying naptime into three categories: ≥1 hour, <1 hour, and no nap. The proportion of children taking naps increased with age, especially on school days.
Sleep patterns Total Age group (years) P-value Area P value 6– 9– 12– 15–17 Urban Rural School-days Wake-up time 6:22±0:32 6:40±0:26 6:31±0:28 6:14±0:31 6:06±0:29 <0.0001 6:23±0:32 6:21±0:32 <0.0001 Bedtime 21:43±1:09 20:56±0:41 21:03±0:46 21:43±0:54 22:56±0:48 <0.0001 22:00±1:06 21:29±1:09 <0.0001 Sleep duration at night (h) 8.64±1.34 9.73±0.69 9.46±0.81 8.52±1.00 7.16±0.84 <0.0001 8.39±1.27 8.86±1.36 <0.0001 Weekends Wake-up time 7:57±1:04 7:52±0:52 7:53±0:57 8:00±1:06 8:03±1:15 <0.0001 8:01±1:05 7:53±1:03 <0.0001 Bedtime 22:08±1:06 21:33±0:49 21:43±0:54 22:11±1:01 22:57±1:01 <0.0001 22:22±1:03 21:56±1:06 <0.0001 Sleep duration at night (h) 9.81±1.25 10.32±0.82 10.17±1.05 9.81±1.18 9.10±1.34 <0.0001 9.65±1.21 9.95±1.27 <0.0001 Table 2. Sleep patterns of children and adolescents aged 6–17 years — China, 2016–2017.
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