Acute sleep loss increases dietary intake in preschoolers both on the day of and the day after sleep restriction, found a University of Colorado study.
Pre-schoolers in a recent study, all regular afternoon nappers, were deprived of roughly three hours of sleep on one day – they had no afternoon nap and were kept up for about two hours past their normal bedtime – before being awakened at their regularly scheduled times the next morning.
During the day of lost sleep, the 3- and 4-year-olds consumed about 20% more calories than usual, 25% more sugar and 26% more carbohydrates, said Assistant Professor Monique LeBourgeois, lead study author at the University of Colorado Boulder (CU 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% more calories and 23% 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 of the department of integrative physiology. According to the National Sleep Foundation, about 30% of pre-schoolers do not get enough sleep.
“We found that sleep loss increased the dietary intake of pre-schoolers on both the day of and the day after restricted sleep,” she said. These results may shed light on how sleep loss can increase weight gain and why a number of large studies show that pre-schoolers who do not get enough sleep are more likely to be obese as a child and later in life.
Even with extensive obesity prevention efforts in the past decade, childhood obesity remains an epidemic. In 2014, 23% of children under the age of 5 years in the US were overweight or obese, said LeBourgeois. Childhood obesity increases the risk for later life chronic illnesses like diabetes and is associated with 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 – meaning when their sleep was optimised, restricted and recovered – which gave them control over how kids could differ individually in their eating preferences and sleep.
The children in the study – five girls and five boys – each wore small activity sensors on their wrists to measure time in bed, sleep duration and sleep quality. Parents logged all food and beverages consumed by the pre-schoolers, 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 CU 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.
Other CU Boulder co-authors include Professor Kenneth Wright, graduate student Sherin Cherian and postdoctoral fellow Salome Kurth. University of Michigan co-authors include Dr Julie Lumeng and Associate Professor Alison Miller.
The new study opens the door for a number of follow-up studies using larger samples, experimentally controlling dietary intake and objectively measuring energy expenditure in children. The study was funded in part by a National Institute of Mental Health grant to LeBourgeois and undergraduate research grants to Mullins from CU Boulder.
Epidemiological findings suggest short sleep duration is associated with overweight and obesity across the lifespan. In adults, experimental sleep loss increases caloric intake more than total daily energy needs, thus leading to weight gain. To date, little is known about the relationship between sleep restriction and dietary intake in preschool children. Healthy children (n = 10; 41.2 ± 5.4 months; 5 females) followed a strict sleep schedule for 5 days before each experimental condition: 1 day of baseline sleep (nap and scheduled bedtime/wake time) and 1 day of sleep restriction (no-nap and ~2.3 h bedtime delay). Standardized parent-report dietary intake measures were obtained on baseline, sleep restriction and sleep recovery (ad libitum sleep opportunity in the 24-h following sleep restriction) days. As designed, children slept ~3 h less on the sleep restriction than the baseline day (P < 0.001), with no significant differences in sleep between baseline and recovery days (verified with actigraphy). Repeated-measures anovas indicated differences across conditions in total kilocalories, sugar, carbohydrate and fat intake (all P < 0.05; no differences in protein). Post hoc tests revealed that compared with baseline, children consumed 21% more kilocalories, 25% more sugar and 26% more carbohydrates on the day of sleep restriction, as well as 14% more kilocalories and 23% more fat on the day of sleep recovery (all P < 0.05). Findings suggest that acute sleep loss increases dietary intake in preschoolers both on the day of and the day after sleep restriction. Increased kilocalorie intake may promote weight gain over time and be a mechanism through which short sleep contributes to childhood obesity risk.
Elsa N Mullins, Alison L Miller, Sherin S Cherian, Julie C Lumeng, Kenneth P Wright, Salome Kurth, Monique K Lebourgeois