Effects of Sleep and on Childhood Obesity and Multiple Studies

Around the world there are very large numbers of obesity in children. Obesity is one factor that will carry on into your adulthood if not treated or prevented from happening. The International Journal of Obesity recognized this and decided to do a study on the effect of sleep on childhood obesity. This journal does multiple studies on obesity and the multiple factors as to why children and adults become obese.

They were trying to figure out whether there was a link between the hours of sleep you get at night and your BMI score; body mass index. Within there study they referred to another article by Kagamimori, Yamagami, Sokejima titled, “The relationship between lifestyle, social characteristics and obesity in 3-year-old Japanese children”, which touched on the ideas that children who reported shorter sleep duration actually had higher BMI. All five authors of this journal article are reputable professors from the University of Munich and part of the Institute for Social Pediatrics and Adolescent Medicine.

The population they used in this study of the effects of sleep on childhood obesity was a group of about 6,882 five and six year olds in Germany. The participants were selected by taking 8 of the 76 communities in Bavaria, and having them distribute a questionnaire to families. They decided to only use 6 of the 8 communities questionnaire results because the other two return percentages were too small. Of the 7,754 questionnaires they received back, the researchers could only use the 6,882 mentioned earlier because the other 872 questionnaires did not have children ages 5 or 6.

The main research design they used was a cross-sectional study. Previously mentioned was the fact that they could only use the 6,882 questionnaires because they others were not compatible to the study. The researchers measured overweight as defined as BMI >90th percentile and obesity as BMI >97th percentile. Meaning any child that had a body mass percentage higher then the 90th-97th percentile were considered overweight or obese. The basis for these percentiles were pulled from Bavaria’s school health exam information that is able to be seen by the public. The questionnaires included multiple questions like: When does your child go to bed or when does your child get up in the morning? The answers to these questions were multiple choice form. 

The researchers also considered other factors as to why the children were overweight or obese. These factors included parents high BMI score, parents education, single parents, smoking during pregnancy, population density, age introduced to complementary foods, high birth weight, high weight gain in first year, time spent on television or video games, regular sports played, amount of snack intake, number of main meals, total calorie intake, and lastly whether the child was breastfed or not. 

While they were studying the effect of lack of sleep on children, they also had to include other factors as to why these children were overweight or obese. Considering how they answered to any of the questions on the questionnaire determined whether or not the other factors were significant in the BMI of the child. These different factors would be better known as cofounding factors to the amount of sleep the child gets at night. When looking at the results the researchers only took into account the cofounding factors that were statistically significant.

This was a very normal research design and they used quantitative analysis because they used statistics for the amount of sleep the children were getting in order to find the percentile they were in. For the first part of the questionnaire, which asked about specific times of when they went to sleep and times they woke up. This data would be considered quantitative date because they used a statistic hypothesis test called, two-proportion z-test. This compares the proportions of high body mass to the amount of sleep each percentile was getting. When they looked at the cofounding factors they also use statistical testing. They used an association test to see the strength of the overweight/obese children and their cofounding factors. Lastly they combined the two test results by using an adjusted odds ratio based on their amount of sleep they had and other statistically signifiant independent factors.

This study had very few limitations. The first limitation worth talking about was the fact that when using a questionnaire based research tool, you have to remember not every single person you send them to will return them. They had to eliminate two communities from their study because the low return rates of their questionnaire. Another limitation they had was lack of information on each household they had sent the questionnaires to, meaning they did not know the age of every child in the house. They had to disregard about 872 questionnaires. The last real limitation they had in this study was the fact that there are so many cofounding factors as to why a child is obese/overweight. It is hard to determine whether the cause of the heaviness is due to lack of sleep or something else is one struggle you face with a cross-sectional study.

After looking the chart and analyzing the results, they were very eye opening and determined that there was a link between children getting less then 10 hours of sleep and the BMI score. Of the 6,862 children given the questionnaire about 961 reported that they get less then 10 hours of sleep per night. Out of the 961 children, 15.6% had high body fat, 14.5% were overweight, and 5.4% were obese. Considering how horrible childhood obesity is these are very shocking numbers, and if this study was done on a larger scale this could become a large problem in the world. Even though they were studying the effect of sleep duration to high BMI scores, they also had to consider the other cofounding risk factors into the results. 

The risk factors that were reported the most on the questionnaires were parents with high BMI, high birth weight, maternal smoking in pregnancy, high weight gain in first year, watching TV or playing videogames for more than 1 h, eating snacks while watching TV, early introduction of complementary foods and having been given a bottle containing milk or carbohydrates to sleep. The strongest protective factors in the bivariate analyses were sleeping for 11.5 h or longer, high level of parental education, breastfeeding and regular sports activities in a club.