This is the second post on the effect of sleep deprivation on children and focuses on obesity.

This is really the story of one scientist who just didn't believe what was apparently gospel about children getting fat because of sedentary behavior - especially related to television viewing. 

Dr. Elizabeth Vandewater at the University of Texas at Austin took on the challenge to prove that lack of exercise was not the cause of obesity. First, she found that obese children watch no more television than kids who aren't obese. Then she found that children only watch seven minutes more TV today than they did in the 1970's and while video games and internet surfing take up an additional 30 minutes on average on top of TV viewing, obesity appeared in the 1980's well before video gaming and internet usage occupied children's lives. She concluded that there was another cause.

Her proof of lazy science led to an effort to find the cause and it was Dr. Eve Van Cauter who discovered a 'neuroendocrine cascade,' which links sleep to obesity. "Sleep loss increases the hormone ghrelin, which signals hunger, and decreases its metabolic opposite, leptin, which suppresses appetite. Sleep loss also elevates the stress hormone cortisol. Cortisol is lipogenic, meaning it stimulates your body to make fat. Human growth hormone is also disrupted. Normally secreted as a single big pulse at the beginning of sleep, growth hormone is essential for the breakdown of fat."

In light of this discovery, sleep scientists have performed a number of analyses on large datasets of children. All the studies point in the same direction: on average, children who sleep less are fatter than children who sleep more. This inspired other countries to engage in the debate and studies in Japan (first graders), Canada (Kindergarten boys) and Australia (young boys) have concluded that children who get less than 8 hours sleep have a 300% higher rate of obesity than those who get a full ten hours of sleep. Research in Houston among middle schoolers and high schoolers showed that the odds of obesity went up 80% for each hour of lost sleep.

Van Cauter went on to discover that the stage of 'slow-wave sleep' is especially critical to proper insulin sensitivity and glucose tolerance. I will not go in to more detail on this other than to say that children spend over 40% of their sleep time in the 'slow-wave sleep' state, much more than adults and perhaps this an explanation for why obesity is much stronger in children than in adults.

So ironically what Vandewater and Cauter have discovered is that contrary to what was believed about exercise being a key driver against obesity. In fact children should spend more time doing the most sedentary inactivity possible - sleep.

This proves to me that those who challenge current belief systems are the ones who can change our future. It's disruptive and at times annoying but thank goodness for their challenging nature. Here's to the disbelievers.