Researchers at the Brigham and Women’s Hospital in Boston showed the 14 participants of the study 20 colour photographs of adult faces with corresponding names and asked to memorise them.

After 12 hours, they were shown the photos again with the names either matched as earlier or not.

Apart from being asked whether the photos and names matched, participants were to rate their confidence on a scale of one to nine.

“We know that many different kinds of memories improve with sleep. While a couple of studies have looked at how naps might affect our ability to learn new faces and names, no previous studies have looked at the impact of a full night of sleep in between learning and being tested,” said Jeanne F. Duffy, associate neuroscientist in the Division of Sleep and Circadian Disorders of the hospital.

Each participant took the test twice — once with an interval of sleep in between and once with a period of regular, waking day activities in between.

When given an opportunity to sleep for up to eight hours, participants correctly matched 12 per cent more of the faces and names.

“We found that when participants were given the opportunity to have a full night’s sleep, their ability to correctly identify the name associated with a face — and their confidence in their answers — significantly improved,” she added.

The new findings, conducted on healthy subjects in their 20s, suggest that sleep after new learning activities may help improve memory.

The findings were published in the journal Neurobiology of Learning and Memory.