New research from the University of Otago, published in the journal Pediatrics yesterday, has found that a lack of sleep during childhood may be contributing to the increasing rates of adult obesity.
The study followed more than 1000 children born in Dunedin, New Zealand, between 1972 and 1973 until they were 32 years of age. Parental reports of bed times were collected at ages 5, 7, 9 and 11 years and were used to estimate sleep times.
Results showed that shorter sleep times were significantly associated with higher adult Body Mass Index (BMI) values. The association was independent of a number of important familial and lifestyle predictors of adult BMI, including early childhood BMI, parental BMIs, physical activity, television viewing and smoking.
This research did not indicate a mechanism for the association between short sleep time and risk of obesity, but possible explanations were suggested. For example, elevated levels of ghrelin (a hormone that stimulates appetite) and decreased levels of leptin (a hormone that suppresses appetite) may be responsible. Tiredness resulting from shorter sleep times may also reduce physical activity as well as altering dietary habits – with people seeking high-energy food to compensate for their low energy levels. It may also be that spending more time sleeping reduces the opportunity to eat. The researchers comment, however, that unfortunately there is insufficient information available on food consumption and physical activity during childhood to explore whether the association between childhood sleep time and adult obesity is mediated by these factors.
More research is clearly needed in this area; in the meantime, ensuring children get enough sleep may be an important strategy for stemming the current obesity epidemic.
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Landhuis CE, Poulton R, Welch D, Hancox RJ. Childhood sleep time and long-term risk for obesity: a 32-year prospective birth cohort study. Pediatrics, 2008; 122: 955-960.