Daydreams are not just a time lapses with starry eyes. They are an important part of our physiology, just like our nightly dreams. In one study, 96% of subjects drift into daydreams at least one time a day. Our mind tends to wander while we are engaged in mundane or repetitive tasks like driving home from work, digesting a meal, or jogging.

Daydreaming has a special protective function. This time is a mental vacation relieving stress and boredom and help us prepare for future. This conclusion was made after studying people with mental disorders like autism and Alzheimer’s disorder. Brain regions involved in normal daydreaming don’t light up in people with autism and Alzheimer’s disease, which led researchers to wonder what “normal” functions are represented by these regions.

It was discovered that the parts of the brain that drifted off during day dreaming are responsible for many other things. Neurologist Marcus Rachile (Washington University, St. Louis) uncovered one of those regions in 2001 using positron emission tomography (PET). Researchers dubbed the active cells during daydreaming the default-mode network because they appear to stay “alert” while the rest of brain is relaxing. These cells are relaxing when the brain is engaging in active goal oriented activity like math problems. It is believed that these cells somehow related to emotional processing because they are not functional in people with low emotional activity who also could not recognized faces like autism and Alzheimer’s.

In 2006, Daniel Kennedy (University of California, San Diego) compared the brain activity of 12 persons with autism and 14 without. The results showed that the brain cells of healthy people easily switched from active to default mode but autistics brains stuck in one mode and default network was not involved.

One theory of autism is that it is due to underdevelopment of the medial prefrontal cortex. People with autism think very concretely about things or people and are less likely to engage in fantasy or emotional thinking. Studies of people with damaged to the prefrontal cortex show that they often exhibit similar behaviors.

In case of Alzheimer’s disease, default – mode network is disrupted in the medial parietal cortex, the lateral parietal cortex and hippocampus – all of which play an important role in the remembering past and planning for future. People with Alzheimer’s do not care much about the future and their default cells are not active during the rest. It looks like these people just pass time, according to Jessica Andrews- Hanna from University of Colorado.

It is interesting that the deposition of amyloid plaques (protein deposits that have been associated with the symptoms of Alzheimer’s disease) seems to mirror default mode network. According to Michael Grecius, Director of the Functional Imaging in Neuropsychiatric Disorders Lab at Stanford University, there are several systems of resting networks in the brain. Now that we have discovered the Alzheimer’s connection, it seems possible that other neuro-generative disorders target different resting networks.

To put it simply, when people stop daydreaming, their emotional and cognitive health is in jeopardy. The term “mind wandering” has been given a bad rep, but it is actually a good thing, very adaptive and functional. Daydreaming about the past consolidates memories. When we daydream about the future, it helps us to prepare better.

Learn to let your mind to relax and give a freedom to your fantasy.

Source: Science Illustrated, 2010 Jan/Febr, p.46-47