In the first national and representative study of the US population in real time and sleep and diet, researchers have linked patient reports of sleep for 7 to 8 hours to eating a varied diet, and sleeping 5 to 6 hours or less with a more unhealthy, higher-calorie diet. “The study is important because it provides the first national snapshot of how diet patterns mesh with sleep in the real world,” says Michael A. Grandner, Ph.D., the study’s lead author and clinical psychologist at the University of Pennsylvania in Philadelphia. “Now that we have this snapshot, we need to delve deeper and see if there is cause and effect, and see if poor quality sleep is contributing to the obesity epidemic.”
Grandner and colleagues used information from the Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey (NHANES), a highly regarded survey that combines questionnaires completed by patients with a medical exam. The group sampled in the survey is chosen so that it represents the U.S. population of all ages and demographics. Researchers examined the dietary habits of people in four categories: “very short” sleepers (who slept fewer than 5 hours a night), “short” sleepers (who slept 5 to 6 hours a night), “normal” sleepers (who reported sleeping 7 to 8 hours a night), and “long” sleepers (sleeping 9 or more hours a night). Women reported very short or long sleep far more often than men. Both African-Americans and Asians more frequently reported very short and short sleep. People with a lower level of education reported sleeping less than other groups. People who reported sleeping 5 to 6 hours reported the highest total calorie intake. People who reporting sleeping the fewest number of hours had the least variety in foods consumed, while normal sleepers had the most varied diet. “Food variety is generally considered an indicator of the quality of a diet,” said Dr. Grandner. Variety gives a wider range of nutrients and better assurance that you get what you need for good health.
Very short sleepers ate fewer total carbohydrates and lycopeine, which is found in fruits and vegetables. Short sleepers consumed less vitamin C. Long sleepers drank more alcohol than others. Long sleepers ate had lower levels of theoobromine, a nutrient found in chocolate and tea.
Before this study, “there has been little to nothing known about dietary patterns as they relate to sleep in the real world,” Dr. Grandner added. The study is clearly preliminary, he acknowledged, but it is a good starting point to see how sleep and diet interact. Researchers already have learned that short sleep is related to diabetes and cardiovascular disease.
A previous study in the October 2012 issue of the journal Sleep by Karen Matthews, Ph.D., and colleagues from the University of Pittsburgh Department of Psychiatry found that if sleep-deprived teens could get one more hour of sleep, they could lower their risk for insulin resistance and subsequent diabetes.
In a review of studies published between 1996 and 2011 on sleep deprivation and weight regulation by Sharon M. Nickols-Richardson, Ph.D., Pennsylvania State University, in the October 24, 2012 Journal of the Academy of Nutrition and Dietetics found reduced insulin sensitivity, increases in ghrelin, and decreased leptin among sleep-deprived individuals. Yet another study presented at the June 2012 SLEEP 2012 by Stephanie Greer, a graduate student at the University of California Berkeley Sleep and Neuroimaging Lab used MRI scans revealed that specific regions of the brain involved in making food choices were disrupted with sleep loss, with short sleepers having frontal lobe disruption, or a failure to integrate all the appropriate choices people are more able to make with longer sleep.
The field is still rather new, according to Dr. Grandner. “Next,” he said, “we hope to determine if the best mix of nutrients for good sleep quality can be identified and if we can then help reduce obesity, heart disease, and diabetes. He added: “If the best mix of nutrients for good sleep quality could be identified, it’s possible we could help reduce obesity, heart disease, and diabetes.”