A new study suggests that solid foods improve infants' sleep, but some doctors are skeptical

Research Summary
Hayley Roper
Research Assistant

A recent study published in JAMA found that introducing solid foods early on in a baby’s diet improved sleep. The results have received a great deal of attention, but some doctors urge caution.

The new results are from data collected between 2008 to 2015 for the Enquiring About Tolerance (EAT) study. The primary goal of this UK study was to determine if introducing certain allergenic foods (for example, peanuts) earlier than the typical recommendation of 6 months, would decrease the risk of developing a food allergy.

The EAT study was a Randomized Control Trial. This means that the families were randomly assigned to either an experimental group or a control group. In this case, the experimental group was the Early Introduction Group and the control group was the Standard Introduction group. Families in the Early Introduction Group introduced six allergenic foods starting at 3 months along with continued breast feeding. The six foods were cows’ milk, peanuts, hard boiled egg, wheat, sesame, and fish (cod). Families in the Standard Introduction Group followed the UK government recommendation of exclusive breastfeeding until around 6 months.

Randomized Control Trials are the gold-standard of clinical research. As a result of randomization, there should be no differences (such as biological sex or parental education) between the infants assigned to the experimental and control groups. This is important so that researchers can be more confident that the treatment caused the outcomes. Or in this case, that early introduction of solid foods caused the risk of developing allergies to decrease. When there are differences between the composition of the experimental and control groups, this creates a “confound”. Confounds make it difficult for researchers to determine if the outcomes of a study are a result of the intervention, or to differences between the groups, or both.

For a summary of the original EAT study results, check out Science of Mom’s blog post.

Researchers also collected information on sleep from 1225 babies (out of the 1303 enrolled). Parents of the babies completed sleep questionnaires every month until the baby was 1 year old and then every 3 months until the baby was 3 years old. The researchers then used this information to see if introducing solid foods early on improved the baby’s sleep.

So, does introducing solid food around 3 months improve sleep?

Yes. But not by very much. Infants in the Early Introduction Group slept up to 16.6 minutes more per night at 6 months compared to the Standard Introduction Group. Parents in the Early Introduction Group also reported, on average, roughly two fewer night wakings per week compared to the Standard Introduction Group. The researchers found no difference between the group for the amount of day time sleep.

These results may seem encouraging, especially for parents who could use 15 more minutes of sleep. But some doctors are hesitant to embrace the results.

In a response to the study, Dr. Craig Canapari (pediatric sleep expert) and Dr. Monica Ordway (lactation and sleep expert), highlight that this is a complicated topic and the results are not as straight forward as they seem.

One limitation pointed out by Dr. Ordway is that the researchers did not ask parents about sleep location after the families were randomly assigned to each group. For example, introducing solid foods may decrease the need for nighttime feeding. As a result, parents may move their baby from their bedroom to a separate bedroom, a change that is likely to influence their child’s sleep. Since parents in the Early Introduction Group introduced solids earlier, they may have also changed their child’s sleep location earlier than the Standard Introduction Group. If so, then it is unclear if the change in sleep is a result of introducing early foods, sleep location, or both.

Dr. Canapari also mentions that there are downsides to introducing solid foods early in an infant’s diet, such as increased respiratory illnesses. More on this in Dr. Canapari’s post.

Yet, others argue that the evidence to support the current recommendation for introducing solid foods are out dated. 

So, should parents introduce solid food early on in their baby’s diet to improve sleep? This question remains unresolved and more research is needed. If parents are concerned about food allergies, this might be an option. But, as always, parents should consult with their pediatrician first.