A refreshing night's sleep may be the best way to boost memory, a study suggests.
Researchers found sleep appears to have a dramatic impact on the way the brain functions the next day.
It appears to strengthen connections between nerve cells in the brain - a process key to both learning and memory.
The University of Geneva study was presented to a Federation of European Neuroscience Societies conference.
The researchers studied a group of 32 volunteers who were taught a new skill or shown images they would later have to remember.
The skill tasks included trying to follow a moving dot on a computer screen using a joy stick.
One group of participants was then allowed to sleep normally for eight hours, while others were deprived of sleep or only permitted a nap.
The next day they were asked to repeat the tasks or recall the images while their brains were scanned using a technique known as functional magnetic resonance imaging (fMRI).
Those who had slept properly performed better, and this was reflected in their brain activity.
Lead researcher Dr Sophie Schwartz said: "Our results revealed that a period of sleep following a new experience can consolidate and improve subsequent effects of learning from the experience.
"This improvement comes from changes in brain activity in specific regions that code for relevant features of the learned material."
Dr Schwartz said sleep helped the brain consolidate learned experiences and harden up weak memories which otherwise might fade in time.
However, she said much more research was required. For instance, it was unclear how much sleep was required to have optimum impact.
"We now want to know which brain circuits are involved in these learning effects during the night and if we can experimentally enhance such effects.
"We want to assess how sleep disorders affect emotional and cognitive functioning, and what are the biological factors responsible for these effects."
Important part of life
Dr Neil Stanley, a sleep expert at Norfolk and Norwich University Hospital, said the findings proved just how important it is to get a good night's sleep.
However, a recent poll of 4,000 adults in the UK found only one in five sleep for eight hours a night.
Dr Stanley said: "Sleep is not just a waste of time, it is a very active time and we need it for things like memory and learning.
"During the day we acquire information, but at night we sort that information.
"People complain about sleep deprivation, but now with the 24/7 society and information overload we need our sleep more than ever."