King College London and the St George's University of London have discovered that babies who are given solid foods earlier in life, sleep longer, woke less frequently at night and suffered fewer serious sleep problems.
The findings are in comparison to babies that were exclusively breastfed for around the first six months of life.
The study was published by JAMA Pediatrics and involved 1303 exclusively breastfed three-month-olds from England and Wales.
The participants were divided into two groups.
One group were encouraged to solely breastfeed for around six months in accordance with government guidelines.
Meanwhile, the other group continued to breastfeed but were asked to introduce solid foods to their infants' diet from the age of three months.
Every month for 12 months, parents filled out an online questionnaires, and then every three months up to three years of age.
Questions included the frequency of food consumption and breastfeeding, as well as enquiring into the sleep patterns of the babies.
The quality of life for the mother was also under evaluation, using the World Health Organisation measures of physical and psychological health, social relationships and environment.
From those who took part in the study, 94 percent completed the three-year questionnaire.
This breaks down into 608 participates from the exclusive breastfeeding group, and 607 from the early introduction of food group.
The results found that infants in the group which had solids introduced early slept longer and woke less frequently than those infants that followed standard advice to exclusively breastfeed to around six months of age.
Differences really peaked at six months between the two groups.
At that stage, the early introduction group slept for 2 hours longer per week than the other group, and their night waking frequency decreased slightly.
As for the mums, reports of sleep problems in the household was cited less by the parents in the group who gave solids earlier.
The lead author Professor Gideon Lack from King's College London addressed the findings saying:
"The results of this research support the widely held parental view that early introduction of solids improves sleep.
"While the official guidance is that starting solid foods won't make babies more likely to sleep through the night, this study suggests that this advice needs to be re-examined in light of the evidence we have gathered."
Co-lead author Dr Michael Perkin, from St George's, University of London, also added that:
"We found a small but significant increase in sleep duration and less frequent waking at night. Given that infant sleep directly affects parental quality of life, even a small improvement can have important benefits."
The current advice given by the government is for mothers to try and exclusively breastfeed until around six months of age.
In light of the study the Food Safety Authority (FSA) said:
"The FSA has an important role to play in funding research such as the EAT Study that helped expand our knowledge about how allergies develop. This further analysis of data collected during EAT could be of interest to parents, however, there are limitations to the findings."
"We are encouraging all women to stick to existing advice to exclusively breastfeed for around the first six months of age. If there is any doubt about what's best for your baby, please seek advice from your doctor or health professional."