In previous research, Walker and others found that fact-based memories are stored temporarily in the brain's hippocampus, then sent to the area known as the prefrontal cortex -- which he suspects has more storage space.
''Perhaps what happens is that the hippocampus is actually the short-term way station for memory in the brain," Walker tells WebMD. The hippocampus is good at getting hold of information, but at some point needs to ''download” the information to the pre-frontal cortex, he says.
The nap before learning may help clear out the hippocampus and send the data on to the prefrontal cortex, allowing new information to soak in, Walker says.
''What is new and exciting about this study is, he's shown that sleep, in addition to helping the memory consolidation process, also primes the brain to learn new information," says Jessica Payne, PhD, an assistant professor of psychology at the University of Notre Dame in Indiana, who has also researched the topic.
''Memory really has three stages,'' she says. They are:
- Initial memory encoding, after you learn something new
- Memory storage or consolidation
- Memory retrieval
Most of the sleep research has focused on the consolidation process, she says, although the new study looks at how sleep affects the initial encoding.
The new study findings, Payne says, may be of particular help for aging people who feel their memories are failing. A brief midday nap may help them learn and remember later in the day, she says.
Walker and Payne concede that a 90-minute nap in the middle of a workday isn't feasible for many people. But it may turn out that briefer naps would provide the same, or similar benefits, Payne says.