Americans sleep less than people in any other industrialized country. Could this be one of the contributing factors to our increased incidence of overweight and obesity in the U.S.? According to recent research, America’s hectic lifestyle, fueled by lack of adequate sleep, is definitely feeding the obesity epidemic.
The link between sleep and weight was first noticed in the 1990s. Researchers in Europe were perplexed as to why so many children were getting heavier. The researchers were surprised to discover that it wasn’t how much television a child watched that predicted whether or not he or she was overweight, but how much sleep the child got.
The less children slept, the heavier they were.
Chronic sleep loss triggers hormones that can lower the hormone leptin, responsible for controlling appetite. Lower levels of leptin — which is produced by fat cells and signals satiety, telling the brain that we have eaten enough — are associated with obesity. The hormone ghrelin, which triggers hunger, is produced in the stomach.
Researchers in Wisconsin studied sleep loss on body mass index, an indirect measure of body fat. The ongoing research involved 1,024 state employees between the ages of 30 and 60. Every four years each volunteer would spend a night at a sleep lab. Blood sampling and weight checks were conducted. Every five years each participant completed a questionnaire about sleep habits, and they were asked to keep a six-day sleep diary.
During the 15-year study researchers found that short sleep duration was associated with low leptin levels. There was a 15 percent increase in ghrelin and a 16 percent decrease in leptin in people who consistently got only five hours of sleep. Additionally there was an association seen between sleep duration and BMI. Participants that got only three hours of sleep had a 5 percent increase in body weight. Although this isn’t a great amount, the effect might be why dieting is so disappointing for so many people.
A second, much smaller study, at the University of Chicago involved 12 healthy males in their 20s. The study looked at how sleep loss affects both leptin and ghrelin levels. For two nights the young men were allowed to get only four hours of sleep. Then for two nights they were allowed to spend ten hours in bed, for an average of nine hours of sleep. Hormone levels were measured before, during and after sleep. Questionnaires were completed to assess their hunger and desire for different foods.
After a night of four hours of sleep, there was a 24 percent increase in hunger and a 23 percent increase in appetite. If the young men were allowed to increase their food intake, they would likely have eaten about 550 calories more a day.
As the young men got hungry, there was also a change in their food choices. The most appealing foods were high-calorie, high-carbohydrate foods. Sweets such as cake, candy and ice cream, salty food such as chips and nuts and starchy foods like bread, cereal and potatoes, were items the men claimed they would be more likely to eat. After just two nights of little sleep, fruit, vegetables and dairy products were at the low end of the craving scale.
If normal, healthful, sedentary adults started eating the additional 550 calories, there would be significant weight gain. In the laboratory setting, the young men did not have free access to food. However, in real life, sleep restriction may be an unrecognized risk factor for the epidemic of obesity.
There is growing evidence that if you are sleep deprived, there is a human tendency to eat more. Weight gain is only one of the many side effects of insufficient sleep, but it can lead to long-term health problems, including type 2 diabetes. Additional sleep will not automatically result in weight loss. Sufficient sleep and a regular sleep schedule can go a long way in controlling appetite and promoting a healthy eating pattern.
Weight gain is a complex problem, and lack of sleep alone is not responsible for the obesity epidemic. Personal food choices, activity patterns and food availability all play important roles in weight maintenance. Getting sufficient sleep is one necessary step that is worth the effort. Not only will you benefit from feeling rested, but it also will help toward achieving overall better nutrition and may be even add a few years to your life.
Georgia Clark-Albert is a registered dietitian and adjunct nutrition instructor at Eastern Maine Community College who lives in Athens. Read more of her columns and post questions at bangordailynews.com or email her at GeorgiaMaineMSRDCDE@gmail.com.