A new study shows that preschoolers who are sleep-deprived for just one day tend to consume a greater number of calories on both that day and the following day.
The findings, published in the Journal of Sleep Research, shed light on how sleep loss can increase weight gain and why preschoolers who do not get enough sleep are more likely to be obese as a child and later in life.
The study involved three- and four-year-old children — all regular afternoon nappers — who were deprived of roughly three hours of sleep on one day. This involved getting no afternoon nap and being kept awake for about two hours past their normal bedtimes. The children were then awakened at their regularly scheduled times the next morning.
During the day of lost sleep, the young children consumed about 20 percent more calories than usual, 25 percent more sugar, and 26 percent more carbohydrates, said lead study author Dr. Monique LeBourgeois of the University of Colorado, Boulder.
The following day, the kids were allowed to sleep as much as they needed. On this “recovery day,” they returned to normal baseline levels of sugar and carbohydrate consumption, but still consumed 14 percent more calories and 23 percent more fat than normal.
“With this study design, children missed a daytime nap and stayed up late, which mimics one way that children lose sleep in the real world,” said LeBourgeois, assistant professor in the Department of Integrative Physiology.
“We found that sleep loss increased the dietary intake of preschoolers on both the day of and the day after restricted sleep.”
According to the National Sleep Foundation, about 30 percent of preschoolers do not get enough sleep.
Even with an increase in obesity prevention efforts in the past decade, childhood obesity remains an epidemic. In 2014, 23 percent of American children under the age of five years were overweight or obese, said LeBourgeois.
Childhood obesity increases the risk for future chronic illnesses like diabetes and is linked to low self-esteem and depression. Overweight youth are about four times more likely to be obese as adults.
“We think one of the beauties of this study is that parents were given no instructions regarding the kind or amount of food or beverages to provide their children,” said LeBourgeois. Parents fed their children just like they would on any normal day.
The researchers also studied each child across all study conditions, such as when their sleep was optimized, restricted, and recovered, which helped reveal how kids differ individually in their eating preferences and sleep habits.
Each preschooler wore a small activity sensor on their wrist to measure time in bed, sleep duration, and sleep quality. Parents kept track of all food and beverages consumed by the children, including portion sizes, brand names, and quantities, using household measures like grams, teaspoons, and cups.
For homemade dishes, parents recorded ingredients, quantities, and cooking methods.
“To our knowledge, this is the first published study to experimentally measure the effects of sleep loss on food consumption in preschool children,” said Elsa Mullins, the study first author and a University of Colorado, Boulder researcher who worked with LeBourgeois as an undergraduate.
“Our results are consistent with those from other studies of adults and adolescents, showing increased caloric intake on days that subjects were sleep deprived,” she said.