The brain is an intricate computer. It is affected by many factors - physical and emotional - internal and external. Sometimes the mind wanders off ... or daydreams ... created by any number of triggers or as a pattern in a person's life. I see boredom as one of the key factors in mind wandering as the mind likes stimulation from the minute someone is born. As with all things in the duality of our reality mind wandering can be both positive and negative. It all depends on the circumstances in which it occurs and repercussions that might follow.

Daydreaming

Mind-wandering (sometimes referred to as task-unrelated thought) is the experience of thoughts not remaining on a single topic for a long period of time, particularly when people are engaged in an attention-demanding task. Mind-wandering tends to occur during driving, reading and other activities where vigilance may be low. In these situations, people do not remember what happened in the surrounding environment because they are pre-occupied with their thoughts. This is known as the decoupling hypothesis. Studies using event-related potentials (ERPs) have quantified the extent that mind-wandering reduces the cortical processing of the external environment. When thoughts are unrelated to the task at hand, the brain processes both task relevant and unrelated sensory information in a less detailed manner.

Mind-wandering appears to be a stable trait of people and a transient state. Studies have linked performance problems in the laboratory and in daily life. Mind-wandering has been associated with possible car accidents. Mind-wandering is also intimately linked to states of affect. Studies indicate that task-unrelated thoughts are common in people with low or depressed mood.Mind-wandering also occurs when a person is intoxicated via the consumption of alcohol. It is common during mind-wandering to engage in mental time travel or the consideration of personally relevant events from the past and the anticipation of events in the future. Poet Joseph Brodsky described it as a 'psychological Sahara,' a cognitive desert that starts right in your bedroom and spurns the horizon. The hands of the clock seem to stop; the stream of consciousness slows to a drip. We want to be anywhere but here. Studies have demonstrated a prospective bias to spontaneous thought because individuals tend to engage in more future than past related thoughts during mind-wandering. The default mode network is thought to be involved in mind-wandering and internally directed thought. Read more

Why Mind Wandering Can Be So Miserable, According to Happiness Experts   Smithsonian - February 25, 2017
For you, it could be the drive home on the freeway in stop-and-go traffic, a run without headphones or the time it takes to brush your teeth. It's the place where you're completely alone with your thoughts. 'We still don't know why our minds seem so determined to exit the present moment, but researchers have a few ideas. Scientists, being scientists, sometimes refer to the experience of mind-wandering as 'stimulus-independent thought.' But by any name, you know it: It's the experience of arriving at work with no memory of the commute. When you're engaged in mundane activities that require little attention, your brain drifts off like a balloon escaping a child's hand - traveling to the future, ruminating on the past, generating to-do lists, regrets and daydreams. In the last 15 years, the science of mind wandering has mushroomed as a topic of scholarly study, thanks in part to advances in brain imaging. But for a long time, it was still difficult to see what people's brains were doing outside the lab. Then, when smartphones came on the scene in the late 2000s, researchers came up with an ingenious approach to understanding just how often the human brain wanders in the wilds of modern life.

Mind Wandering: How It Helps and Harms Learning   Open Colleges - September 14, 2014
What happens on a neurological level while our minds wander is actually pretty fascinating. According to the Neuroenergetic Theory proposed by Killeen et al., our attention starts to lag after just twelve seconds of effort because our neurons run out of fuel. Neurons first look to glial cells for lactate, a readily used sugar, and if they can't find it, they look for glycogen, which is stored up at night when we sleep. If our neurons can't find the lactate or glycogen needed to focus, they get exhausted - enabling other parts of the brain to call for attention. That's when the mind starts to wander. These functions that all come from within - like imagination and mind-wandering - have been shown to be really important contributors to creativity. This happens to us all from time to time, especially when we don't get enough rest or the right nutrition. But it can happen more frequently to those of us who just have trouble concentrating, or find ourselves zoning out more than we should. So what''s the result for our daily lives? When is it okay to let our minds wander, and when should we try to resist? The answer may surprise you.