Whether it's worrying or fantasizing, all of us daydream—or let our minds escape from the task at hand.

Now, a new computer model that simulates these periods of mental wandering may give scientists clues about how our brains work. Specifically, the model shows how our brain cells communicate when our minds are either engaged or idle.

Scientists have known since the late 1990s that our brains still fire off nerve impulses—an indicator of activity—even when they're idle. Since then, scientists have identified several brain networks, called "resting state" networks, inside our gray matter where this phenomenon occurs. (See "Is Your Brain Sleeping While You're Awake?")

Since resting state networks are disrupted in the event of brain injuries and cognitive diseases, modeling them may eventually help people with these conditions, Maurizio Corbetta, of the Washington University School of Medicine in St. Louis, said in a statement.

"We can give our [computer] model lesions like those we see in stroke or brain cancer, disabling groups of virtual cells to see how brain function is affected," said Corbetta, co-author of a study on the model published in the July 3 issue of The Journal of Neuroscience. "We can also test ways to push the patterns of activity back to normal."

But wait—before you drift off into la-la land, here are some interesting facts about daydreaming you may not have known.

You daydream less as you get older.

Daydreaming is often about anticipating the future, especially in a fantasy context, notes Peter Delaney, a psychologist at the University of North Carolina, Greensboro.

For instance, young men often have "power fantasies" of what it would be like to be a superhero. But as people get older, the amount of time they spend daydreaming decreases—perhaps as the future shrinks.

Daydreaming makes you forget what you were doing.

If people are asked to daydream about the past, for instance, they tend to forget what they were doing before the daydream started, according to previous research.

The type of daydream also affects how much you forget, according to Delaney and colleagues' research.

When people working on a task were asked to daydream about their childhood home, the older subjects forgot more of the interrupted task than the younger subjects did. That means that the further back in time the daydream reaches, the bigger the forgetting effect.

It's not only temporal, but physical: If you daydream about a vacation abroad versus a vacation out of state, you are likely to forget more of what you were doing because your trip abroad is so out of context—it's like "mentally transporting yourself back there," he said.

Delaney suggests that this should be of special note for people who rely on memory, including those in careers such as medicine: If a doctor who just memorized a drug dosage is stopped in the hallway and asked about her recent vacation abroad, she may well forget the drug information, he explained.

Daydreaming turns off other parts of the brain.

Our brain has two key systems: An analytic part that helps us make reasoned decisions, and an empathetic part that allows us to relate to others.

When confronted with a cognitive task, your brain requires the empathetic area to turn off to get the job done, notes Anthony Jack, a cognitive scientist at Case Western Reserve University in Ohio. (Read "Beyond the Brain" in National Geographic magazine.)

In other words, "if you are engaged in a demanding analytic task, it doesn't leave any room for empathy."

Yet when you are daydreaming, your mind naturally cycles through different modes of thinking, and during this time the analytic and empathetic parts of your brain tend to turn each other off.

Your brain, not your mind, controls your daydreams.

The mind and brain can be thought of as different aspects of the same thing, like the software and hardware of a computer.

"We tend of think of our minds in the driving seat and our brain activity as following," Jack said.

But in fact, the relationship goes both ways. How we daydream and think depends on the brain's structure. On the other hand, that structure is constantly changing in small ways—as we learn new things the connections between nerve cells change. (See brain pictures.)

"Your brain naturally fluctuates in certain ways because of its structure, and that determines the structure of your daydreaming," Jack said.

Daydreaming makes you more creative.

Many times the "dialogue" that occurs when the daydreaming mind cycles through different parts of the brain accesses information that was dormant or out of reach, notes Eugenio M. Rothe, a psychiatrist at Florida International University.

Likewise, the daydreaming mind may make an association between bits of information that the person had never considered in that particular way.

"This accounts for creativity, insights of wisdom and oftentime the solutions to problems that the person had not considered," Rothe said by email.

"A similar process, but more random, also takes place during dreaming."

Still there? Tell us: What do you daydream about?