Dreaming, Napping Can Improve Memory, Study Says

If you're one of the people who thinks sleeping is a waste of time, dream on.

A new study from Harvard Medical School found that napping, and dreaming in particular, can be a surprisingly effective learning tool.

CBS News Medical Correspondent Dr. Jennifer Ashton explained on "The Early Show" that during the study, 99 participants were taught to navigate a virtual maze on a computer screen. Half were then allowed to nap for 90 minutes, while the other half stayed awake. Later that day, all participants were re-tested on the maze task. Those who reported dreaming about the maze significantly improved their performance. They did better than people who had slept, but did not dream, and better than those who stayed awake rehearsing the task in their minds.

Special Section: Dr. Jennifer Ashton

Ashton said scientists don't really know why dreams boost learning because it's such a complex process. However, Ashton pointed out that there are stages of sleep. Most dreaming occurs after 90 minutes of sleep.

"You can think of it almost like putting Jell-O in the refrigerator. You can eat the Jell-O before it's really hardened, but it's really good once it's been locked in, and that's the thinking behind what sleeping does to processing memory."

She added that researchers point out that when you learn something, it is not just dreaming that causes you to remember it. Rather it appears that when you have a new experience, it sets in motion a series of parallel events that allow the brain to consolidate and process memories.

"Our dreams may be how our brain presents to us the memory processing that it's doing," she said. "Some people have viewed dreaming as a mystery or entertainment, but this study suggests it is a by-product of memory processing. Whether you have to remember your dreams to get the benefit is not entirely clear yet, but the researchers suspect not."

To to reap the benefits of dreaming, Ashton said this study used 90 minutes of sleep because participants could enter the REM Cycle, in which you go all the way down into deep sleep then come back up.

But she said people could conceivably reap the benefits in as little as a half hour.

"Studies have shown for sleep and memory, as little as 12 minutes can help remember things better," she said. "Study a list of words. Then nap for 12 minutes. And voila, you do much better on the test."

She added, "Most Americans are chronically tired and sleep-deprived. And those who find they're sleeping more on a weekend to catch up, it doesn't work that way. You need to get a regular amount of sleep -- seven to eight hours is ideal -- every night. And really, it's not just for your physical health, but for your mental and intellectual health as well."