A daydream is a visionary fantasy, especially one of happy, pleasant thoughts, hopes or ambitions, imagined as coming to pass, and experienced while awake. Some people may devote 50% of their awake time with daydreaming. Recently a case study was published in which a 36 year old female has a long history of excessive daydreaming. As a child between 4 to 10 years of age she would spend periods of free time, sometimes several hours, walking in circles shaking a string, while imagining creative stories in which she was the central focus, i.e., ‘‘just like playing school with other kids, but in my head.” Extensive psychiatric and somatic investigations could not find anything wrong with her.

Daydreaming is often associated with hypnotic susceptibility, creativity, dissociation, past trauma or pathology. High fantasizers constituting 4% of the population are those with devoting their awake time with daydreaming. This can amount to 50% of their time being awake. Daydreaming decreases with age, suggesting that it might be normal for normal healthy brain development.

Daydreaming is believed to be one of the altered states of consciousness, the others being: dreaming, the runner’s high, meditation, hypnosis, and various drug-induced states. As with meditation and hypnosis, daydreaming is characterized by drifting, transitory thoughts and a sense of timelessness. However, all three alterations of consciousness share the feature of toning-down external noise as a prerequisite to enable the mental state.

Videogames also takes individuals into fantasies, another world. Videogaming and daydreaming both share an involvement with fantasy. They differ in stimulus dependency. Gaming is more stimulus dependent, while daydreaming is relatively stimulus independent. In a recent published study they looked at the relationship between daydreaming and videogaming. This exploratory study was done in a selected population of 74 participants ( 22 males) from undergraduate psychology courses at a Midwestern university.

high videogaming engagement appears to be associated with a positive-constructive daydreaming style. … positive daydreaming is characterized by enjoyment and anticipation of daydreaming as assisting in problem solving and without any pathological implications

Daydreaming can be constructive not only in videogaming. It’s not a lazy, non-productive pastime, it is now commonly acknowledged that daydreaming can be constructive in some contexts. It can be productive in developing new ideas, or improve creativity.
Cynthia Schupak, & Jesse Rosenthal (2009). Excessive daydreaming: A case history and discussion of mind
wandering and high fantasy proneness Consciousness and Cognition DOI: 10.1016/j.concog.2008.10.002

Arne Dietrich (2003). Functional neuroanatomy of altered states
of consciousness: The transient
hypofrontality hypothesis Consciousness and Cognition DOI: 10.1016/S1053-8100(02)00046-6

Barry Dauphin, Ph.D., & Grant Heller, B.A. (2010). Going to Other Worlds: The Relationships
between Videogaming, Psychological Absorption, and Daydreaming Styles CYBERPSYCHOLOGY, BEHAVIOR, AND SOCIAL NETWORKING DOI: 10.1089/cpb.2009.0065