Early sleeping habit may change body composition for life

By Kelly Frances

In any English conversation class, you are likely to hear the question “What is your hobby?”

While Western people might list things like soccer, photography, or reading, in Korea one of the most popular answers is "Sleeping."

It’s common knowledge that getting too little sleep during childhood can lead to serious health issues. However, new research suggests that the composition of the body ― the ratio of fat, muscle and bone ― could be affected by sleeping patterns of youth, and with lasting effects.

According to a recent study published online in the British Medical Journal, young children who do not get enough sleep are at increased risk of obesity and poor muscle development, regardless of lifestyle factors such as diet and genetic predisposition.

Such findings are grim for the children of South Korea, who sleep an average of just seven hours and 32 minutes per night, according to Statistics Korea. A nationwide survey found that 75.3 percent of young Koreans do not get the recommended amount of sleep, which is eight hours and 30 minutes per night according to the U.S. National Sleep Foundation.

Prof. Won Chang-won of the Family Practice Department at Kyung Hee University Medical Hospital blames unhealthy routine, too much Internet and poor parental guidance for the Korean children’s sleeping habits.

“Many (Korean children) go to bed late in the night and get too little sleep,” he said. "This is because they blog and play Internet games late into the night, and their parents also fall asleep late watching TV and mixing with friends.”

While numerous studies have indicated a consistent relationship between shorter sleep duration and increased body weight in children, doctors are still not certain how sleep and body composition interact in early childhood, and note that further research needs to be conducted to establish a clear cause and effect. Won agrees, adding that daytime sleepiness and decreased desire to learn are especially prominent in sleep-deprived children.

The study, led by a team based in New Zealand, identified 244 children who were taking part in The Kiwi Family Lifestyle, Activity, Movement and Eating (FLAME) program. Each child's weight, height, body mass index (BMI), and body composition were measured every six months from three to seven years of age. The study also took factors such as birth weight, mothers' education, income, BMI, smoking during pregnancy and ethnicity into consideration.

The results show that young children who sleep less are at a significantly increased risk of having a higher BMI by age seven, even after controlling other risk factors that have direct effects on body weight. Interestingly, each additional hour of sleep per night at ages three to five was associated with a reduction in BMI of 0.49 and a 61 percent reduction in the risk of being overweight or obese at age seven. In other words, those who received more sleep at the beginning of the study were significantly less likely to be obese at age seven.

Most importantly perhaps, the notable deviations in BMI were specifically due to differences in fat mass, rather than muscle or bone, showing that getting poor sleep has distinctly negative effects on body composition. In plain terms, less sleep leads to a tendency for kids to have more fat and less muscle, regardless of their overall weight.

Won notes that there are signs of sleep deprivation which are easily observed by parents or teachers. They include frequent napping, difficulty in concentrating on studies, and low test grades. He urges parents to take an active role in preventing permanent damage by establishing healthy routines and teaching through example.

“Parents should be role models of going to bed early for their children and restrict Internet game[s] late at night,” he said.

The writer is a guest columnist from Ontario, Canada, and is currently living in Seoul. She welcomes topic suggestions from readers, and she can be reached at kellyfrancesm@gmail.com