Naps during the day of at least a half hour help infants retain new behaviors learned earlier, according to researchers from the University of Sheffield.

"These findings are particularly interesting to both parents and educationalists because they suggest that the optimal time for infants to learn new information is just before they have a sleep," says Dr. Jane Herbert from US's Department of Psychology.

In the study, which is believed to be the first of its kind, researchers worked with 216 healthy babies between six and 12 months old.

To test their ability to retain newly learned behaviors, they taught them how to take the mitten off a hand puppet and gave them opportunities to repeat the skill after four hours had passed, and again after 24 hours had passed.

Some of the infants were given 30-minute naps within four hours after learning, and some were not.

Napping and non-napping babies were age-matched and compared against each other and the babies who had napped remembered the learned skill, which attests to the importance of learning before sleeping and napping.

Those who hadn't napped showed no evidence of having retained the skill, according to the study, which was published in Proceedings of the National Academy of Sciences of the United States of America (PNAS).

"Until now people have presumed that the best time for infants to learn is when they are wide-awake, rather than when they are starting to feel tired, but our results show that activities occurring just before infants have a nap can be particularly valuable and well-remembered," says Dr. Herbert.

Parents are advised to make time to put their babies down for a nap, even if it must be done on a flexible schedule.