They also woke around two fewer times at night per week at six months and had just over 9% fewer incidents of waking up during the night over the course of the study.
A study published on Monday in the journal JAMA Pediatrics has found that babies who were introduced to solid foods early slept longer, woke less frequently at night than those exclusively breastfed for around the first six months of life.
The study was supported by the UK Food Standards Agency (FSA), the Davis Foundation, and the UK National Institute for Health Research.
Co-lead author Dr Michael Perkin, from St George's, University of London, said: 'It is a commonly-held belief among mothers that introducing solids early will help babies sleep better, and our study supports this.
"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".
The study's senior author, Dr. Gideon Lack, said in a statement, one of the most essential observations of the study was "more than 50 percent reduction in the number of families reporting severe sleep disturbances in their babies".
They also found that families in the standard introduction group were more likely than those in the early introduction group to report a small problem (OR 1.2, 95% CI 1.05-1.41) or a very serious problem (OR 1.8, 95% CI 1.22-2.61) with their child's sleep.
However Professor Amy Brown of Swansea University, whose research includes weaning of babies, said the benefits revealed by the study were "minimal" in real-world terms, and that other research showed no rewards for early introduction of solids.
The parents also completed online questionnaires that asked about feeding, breastfeeding and sleep duration. She said that "while there was a short period of time in which the infants [in the study] seemed to sleep better, it can be argued that the benefits [of early solid foods] do not outweigh the risks and possible future negative effects". Researchers say that women should still follow this piece of advice. This further analysis of data collected during EAT could be of interest to parents, however, there are limitations to the findings.
Responding to the study, Prof Mary Fewtrell, nutrition lead at the Royal College of Paediatrics and Child Health, pointed out that guidelines for infant feeding are now being reviewed.
'However, the evidence base for the existing advice on exclusive breastfeeding is over ten years old, and is now being reviewed in the United Kingdom by the Scientific Advisory Committee on Nutrition and in the EU by the European Food Safety Authority. If there is any doubt about what's best for your baby, please seek advice from your doctor or health professional'. The first group breastfed exclusively until they turned 6 months old, while the second ate solid foods along with breastmilk as soon as they turned 3 months old, BBC reported.