Children who get less sleep in infancy and early childhood may be at greater risk of being overweight or obese during mid-childhood, according to a study published today in the journal Pediatrics.
Over the past 20 years, studies have documented that the amount of daily time spent sleeping has declined for infants, children, and adolescents. Cultural changes have likely contributed to this trend, including more 2-parent working families and longer work hours. There is some evidence that reduced duration of sleep can to contribute to negative health outcomes, such as increased risk factors for cardiovascular disease.
Elsie M. Taveras, MD, MPH, of Massachusetts General Hospital for Children, and colleagues examined whether infants and young children who slept less than their counterparts were more likely to be overweight or obese in mid-childhood. They asked the mothers of 1046 children about how long their child slept in a typical 24-hour period at 6 months, and then their daily sleep duration for each year between ages 1 year and 7 years.
Overall, 75% of the children were in the normal weight range, 13.8% were overweight, and 11% were obese, based on body mass index (BMI). But compared with children who routinely slept the longest, children in the group with the least sleep were significantly more likely to be overweight or obese: 55.3% had a BMI in the normal range, 10.7% were overweight, and 34% were obese. Children who got the most sleep were the least likely of any group to be obese: 81.7% had a BMI in the normal range, 11.5% were overweight, and 6.8% were obese. The researchers found a similar association when they looked at other measures of weight, including trunk fat and waist-to-hip circumference.
The authors noted that the study has some limitations, including its reliance on parental reports and underrepresentation of Hispanic children. Because the findings are observational, the study cannot prove that sleep deprivation causes weight gain in children. In addition, factors related to lack of sleep that were not controlled for in the statistical analyses may explain the relationship.
The authors propose various mechanisms that might explain how chronic sleep deprivation could contribute to weight gain. For example, lack of sleep may make children feel hungrier and less full. Sleep deprivation may also affect levels of hormones that have been linked to abdominal obesity, such as cortisol, or may upset the body’s circadian clock and gene expression.
Regardless of the exact mechanism, the study suggests that understanding the factors that contribute to reduced sleep in children and helping parents facilitate longer sleep durations for children may help reduce obesity and overweight in children.