Associations between sleep and obesity have been well documented in adults and children, but a new study suggests sleep patterns at the earliest stages of life can set a child on a path toward obesity.
The new study comes from investigators at Brigham and Women’s Hospital and Massachusetts General Hospital, both in Boston.The scientists wanted to understand whether sleep trouble among infants had a similar effect on weight as sleep disorders in adults. To find out, they studied 298 full-term infants who participated in the longitudinal Rise & SHINE cohort study.
Each of the infants in the study wore a sleep monitor on their ankle, and their parents kept sleep journals. The ankle monitors were worn for 3 nights when infants were one month old and 3 more nights when the infants were 6 months old. Researchers tracked metrics such as nighttime sleep duration, waking after sleep onset, and number of waking bouts in excess of 5 minutes. They then compared those data to size measurements, using growth charts from the World Health Organization.
The investigators found that, for each extra hour of sleep an infant got, his or her odds of being overweight from 1 to 6 months old decreased by 26%. Similarly, as the number of nighttime wake-ups in excess of 5 minutes decreased, so did the odds of being overweight. The one exception was waking after sleep onset; changes in that metric did not appear to correlate with weight. The findings were published in the journal Sleep.
“In this study, we found that not only shorter nighttime sleep, but more sleep awakenings, were associated with a higher likelihood of infants becoming overweight in the first six months of life,” said study co-author Susan Redline, MD, MPH, in a press release.
Though the study only dealt with infants, the authors said the data suggest that poor sleep early in life may contribute to obesity later in life. That conclusion aligns with a 2017 study that looked at links between childhood obesity and adult obesity. In that study, investigators found that 2-year-olds who were obese had a 75% chance of being obese when they reached age 35. The risk of obesity at 35 appeared to increase throughout childhood, with obese 19-year-olds having an 88% chance of still being obese at age 35. The inverse was also true: children who were not obese at age 2 saw their risk of obesity at age 35 decrease through their childhood and teenaged years.
A report by the T.H. Chan School of Public Health at Harvard found one-tenth of US healthcare costs were related to obesity in 2006, and estimated that by the year 2030, the US could spend $66 billion per year on obesity-related healthcare.
Redline and colleagues listed a number of limitations to their study. They said African-Americans and people of lower socioeconomic status were under-represented in their data set. They also noted that their study did not include potentially confounding factors, such as the duration of breastfeeding for the infants in the study.
Still, Redline said the data show how healthy sleep plays an important role in health, even in infancy.
“Parents should consult their pediatricians on the best practices to promote healthy sleep, like keeping consistent sleep schedules, providing a dark and quiet space for sleeping, and avoiding having bottles in bed,” she said.