Nighttime sleep patterns in babies linked to later obesity

Adequate nighttime sleep has been shown in many studies to influence body weight in adults. But the same pattern may also be true for infants and toddlers. A study published Monday found that how much and, here’s the key -- when -- babies sleep can be important to weight gain later in life.

Researchers from the University of Washington and UCLA used data from a national survey of children and adolescents to study 1,930 children ages 0 to 13. Information on the children was collected on two occasions, in 1997 and 2002.

The study showed that, by 2002, about one-third of the children were overweight or obese -- numbers that match many other national surveys conducted in recent years. As for the sleep-weight connection, the researchers found a strong link between duration of nighttime sleep among children ages 0 to 4 and subsequent obesity at ages 5 to 9 years. This association held up even when the researchers controlled for other factors that affect obesity, such as parents’ body-mass index, family socioeconomic status and the hours the child watches television.

The link was true only among children ages 0 to 4, not in the older children.

“These findings suggest that there is a critical window prior to age 5 years when nighttime sleep may be important for subsequent obesity status,” the authors wrote. The study is published in the Archives of Pediatric & Adolescent Medicine.

The fact that napping did not affect future weight, they said, “suggests that napping is not a substitute for nighttime sleep. There is some evidence that nighttime sleep and naps serve different physiological functions.” For example, napping may reduce daytime stress and increase attention span and alertness necessary for learning.

How nighttime sleep patterns influence weight is not fully understood. It could be that babies and toddlers who don’t get enough sleep aren’t as physically active during the day and eat more to increase their energy. But it’s also likely, the authors said, that hormones play a role. Hunger and appetite increase when the hormone leptin is low and the hormone ghrelin is high. Low leptin and high ghrelin levels are found in adults who experience short sleep duration at night.

-- Shari Roan, Los Angeles Times

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