Introducing solid foods earlier may improve infant’s sleep, study shows

Dr. Amitha Kalaichandran MD

Most new parents dimly remember getting 6, 7, or even (gulp) 8 whole hours of uninterrupted sleep. After a new baby arrives, they may wait months — perhaps years — for a restful night’s sleep again. Google searches for infant sleep training are common, and the business of “baby sleep experts,” is booming.

Now a recent study, published in JAMA Pediatrics suggests that introducing infants to solids early on may be associated with improved sleep — and better sleep in baby can mean better sleep for parents.

This study suggests that better sleep for everyone may be related to the food babies eat: introducing solid foods earlier may lead to longer sleep time and fewer nighttime awakenings. The researchers, based at Kings College London, UK, conducted a randomized controlled trial — the Enquiring About Tolerance (EAT) study — originally to look at the early introduction of allergenic foods (cow’s milk, peanut, eggs, sesame, white fish, and wheat) on the later development of allergies.

That study was published in the New England Journal of Medicine few years ago, but in one section of their survey, they asked parents to document sleep habits in their infants. Babies randomized to consume solids before six months of age had 9% fewer nighttime awakenings and slept an average of 17 minutes more than those infants who only received breastmilk before six months of age. No infant in the study received formula.

The children in the “early introduction of solids” arm of the trial were given solids (e.g. rice-based baby food) on an average of 4 months of age. The children in the “late introduction of solids” were on average 24 weeks of age, so just under 6 months.

Dr. Michael Perkin, senior lecturer in clinical epidemiology in the Population Health Research Institute and Consultant in Pediatric Allergy in St. George’s Hospital in the U.K., was the co-principal investigator in the study.

“It’s a widely believed idea among parents that once babies are on solid food, they sleep better, so we added sleep questions into our survey to test this theory,” Perkin told ABC News, “Because the infants were randomized to either early or late introduction of solids, it’s hard to attribute the improved sleep to anything other than introducing solids.”

Perkin isn’t clear as to what the mechanism behind the improved sleep might be, but hypothesizes that the higher calories in solids may result in the infants feeling full for longer, compared to a liquid diet of breastmilk, which may be quickly digested and cause them to wake up more frequently to feed.

According to the National Sleep Foundation, which revised its guidelines in 2015, newborns and infants up to 4 months should normally sleep between 14 and 17 hours a day, and this can decrease to 12 to 15 hours between 4 and 11 months of age — but there’s no guarantee they will do it at night.

Dr. Craig Canapari is the Director of the Pediatric Sleep Clinic at Yale School of Medicine and frequently sees infants and children with sleep concerns.

“Sleep in infants is pretty chaotic during the first month or so, and babies basically wake up, feed, stay awake for a short period of time and go back to sleep. There’s a huge range in what’s normal during the first month or so,” Canapari told ABC News, “In terms of nighttime awakenings, it’s normal for infants to wake up every 2 to 3 hours to feed for the first month or so, and this might then increase to every 3 to 4 hours.”

He cautions that a baby under three months that doesn’t wake up to feed every four hours, or an infant who snores, are red flags that warrants exploration with a pediatrician.

Canapari also cautions against ‘sleep training’ at too young of an age.

“The term ‘sleep training’ is problematic because there is a certain connotation. Around 2 months of age, I recommend encouraging the infant to sleep when they are drowsy but awake. But I explore other ideas when they are at least 4 to 6 months,” Canapari told ABC News.

With respect to the study, Canapari points to some evidence that shows that caloric content and digestibility may explain some of the findings.

“We have known for awhile, for instance, that breastfed babies wake up earlier and feed a bit more frequently than formula-fed babies because they digest breastmilk more easily and therefore faster, so get hungrier faster,” Canapari told ABC News, “It may also have something to do with brain maturity, so by the time infants are mature enough to tolerate solid foods, it may just happen to be when they are also able to better regulate their sleep cycles.”

The American Academy of Pediatrics (AAP) currently recommends introducing solid foods between 4 to 6 months of age, and the evidence for introduction closer to the 4-month mark was largely influenced by the first portion of the EAT study, which found lower allergy risk among infants introduced to solids earlier. However, the AAP does caution that some evidence suggests introducing solids earlier than 4 months may be associated with increased weight gain and body fat percentage in infancy and early childhood.

Perkin explains that one of the reviewers recommended they use objective device like an “actigraph,” which is any wearable device that measures movement during sleep to assess how well infants in both groups were sleeping, as opposed to relying on the parent’s report, but Perkin indicates that it’s unlikely that parents would adhere to this.

The biggest question is whether the additional 17 minutes of sleep, and the marginal decrease in nighttime awakenings (while both are statistically significant) makes a difference in real live.

“The question is whether this difference is meaningful, and to that I’d say it’s debatable, Canapari told ABC News, “But the same trial suggested that early solid introduction decreases allergy risk in children, so overall it might be that introducing solids earlier may have multiple benefits.”

Perkin understands the debate, but that most new parents would be likely to cherish 17 minutes.

A physician, epidemiologist, wellness coach, and medical journalist with an interest in the intersection of health, innovation, and culture.

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