Science of Daydreaming

Unlike previously thought, the universal phenomenon of daydreaming is a normal part of our cognitive processes. Daydreaming is defined as “spontaneous, subjective experiences in a no-task, no stimulus, no-response situation…[and] includes unintended thoughts that intrude inadvertently into the execution of intended mental tasks… and undirected ideas in thought sampling during wakefulness” (1). Although a single daydream usually lasts only a few minutes, it is estimated that we spend one-third to one-half of our waking hours daydreaming, although that amount can vary significantly from person to person (2).

In contrast to what its name may suggest, daydreaming seems to be quite different from the dreams experienced during sleep. Another interesting fact about daydreaming is that “the seemingly continual stream of consciousness is discontinuous, consisting of a sequence of concatenated, psychophysiological building blocks … that follow each other in fractions of seconds” (1).

Daydreaming is often looked down upon, as John McGrail, a Los Angeles clinical hypnotherapist, explains: “Daydreaming is looked upon negatively because it represents ‘non-doing’ in a society that emphasizes productivity…. We are under constant pressure to do, achieve, produce, and succeed” (3). Sigmund Freud even believed that fantasies were the creations of the unfulfilled, and that daydreaming and fantasy were early signs of mental illness (2).

Experts now agree, however, that daydreaming is a normal, and even beneficial, cognitive function-albeit one that is largely still not understood. An area of the brain called the “default network,” which becomes more active as the level of external stimulus decreases, is often considered responsible for daydreaming. The default network mainly includes the medial prefrontal cortex (PFC), the posterior cingulated cortex/precuneus region, and the temporoparietal junction (4).

Neuroimaging studies have offered support for this hypothesis, though only indirectly. These studies demonstrated “correlations between reported frequency of task-unrelated thoughts and default network activation during conditions of low cognitive demand, as well as stronger default network activation during highly practiced compared with novel tasks in people with higher propensity for mind wandering.” A different interpretation of these data, offered by Gilbert et al., argued that “instead of mind wandering, activations in the medial PFC part of the default network may reflect stimulus-related thought such as enhanced watchfulness toward the external environment that is also likely to occur during highly practiced tasks”(4).

One-third to one-half of our waking hours are spent daydreaming.

One-third to one-half of our waking hours are spent daydreaming.

A study by Christoff et al. using functional magnetic resonance imaging (fMRI) found that the executive system of the brain as well as the areas of the brain at the core of the default network, namely the medial PFC, the posterior cingulated/precuneus, and the posterior temporoparietal cortex, were, in fact, active during daydreaming. They also found that “brain recruitment associated with off-task thinking is most pronounced in the absence of meta-awareness,” meaning when the person is not aware that he or she is daydreaming. The study also clarified: “Although our findings yield strong support to the notion that the medial PFC is involved in mind wandering, they do not specify whether it is involved in stimulus-independent or stimulus-oriented mind wandering, an important question that remains subject for further research.” (4) An important finding of the study was the activation of the dorsal anterior cingulate cortex (ACC) and the dorsolateral prefrontal cortex (DLPFC), the two main regions of the executive network of the brain, during mind wandering.  The recruitment of the executive system of the brain during daydreaming may help explain why daydreaming “can undermine performance on demanding tasks.” Christoff et al. proposed that this dual activation-of both the default and executive networks-suggested “the presence of conflict inherent to the content of mind wandering. This possibility would also be consistent with observations that the content of mind wandering is closely related to current personal concerns and unresolved matters” (4).

The study then suggested the possible implication of finding that both the executive and default networks of the brain are active during mind wandering. The activation of both the default and executive networks of the brain is similarly seen in both creative thought and “naturalistic film viewing,” (4) suggesting that “mind wandering may be part of a larger class of mental phenomena that enable executive processes to occur without diminishing the potential contribution of the default network for creative thought and mental simulation. Although it may undermine our immediate goals, mind wandering may enable the parallel operation of diverse brain areas in the service of distal goals that extend beyond the current task.” (4)

In another study, Sayette, Reichle-professors of psychology at the University of Pittsburgh-and Schooler-a professor of psychology at UC Santa Barbara-found interesting results of alcohol’s effect on mind wandering. The study reported that “a moderate dose of alcohol simultaneously increases mind wandering while reducing the likelihood of noticing that one’s mind has wandered.” In this study, the consumption of alcohol doubled the incidence of daydreaming during a reading task. The study explained that “these findings represent the first demonstration that alcohol disrupts individuals’ meta-awareness of the current contents of thought. Although novel, this conclusion is consistent with prior observations that alcohol inhibits processes related to meta-awareness.” (5)

An article by M.F. Mason et al. published in Science proposed three possibilities on the reason the mind may wander at all. First, the authors suggested that perhaps stimulus independent thought (SIT) “enables individuals to maintain an optimal level of arousal, thereby facilitating performance on mundane tasks.” Second, they suggested that perhaps SIT “lends a sense of coherence to one’s past, present, and future experiences.” Thirdly, they suggested that perhaps “the mind may generate SIT not to attain some extrinsic goal…but simply because it evolved a general ability to divide attention and to manage concurrent mental tasks. Although the thoughts the mind produces when wandering are at times useful, such instances do not prove that the mind wanders because these thoughts are adaptive; on the contrary the mind may wander simply because it can.” (6)

Although daydreaming is still not fully understood, it is clear that during daydreaming the mind is very active. Marcus Raichle, a neurologist and radiologist at Washington University, sums it up: “When you don’t use a muscle, that muscle really isn’t doing much of anything…. But when your brain is supposedly doing nothing and daydreaming, it’s really doing a tremendous amount. We call it ‘resting state,’ but the brain isn’t resting at all.”(7)


1.     D. Vaitl et al., Psychobiology of altered states of consciousness. Psychological Bulletin. 131, 98-127 (2005).

2.     Daydreaming (2001). Available at (22 May 2010).

3.     C. Frank, Why does daydreaming get such a bad rap? (2006). Available at (22 May 2010).

4.     K. Christoff, A. M. Gordon, J. Smallwood, R. Smith, J. W. Schooler, Experience sampling during fMRI reveals default network and executive system contributions to mind wandering. PNAS. 106, 8719-8724 (2009).

5.     M. A. Sayette, E. D. Reichle, J. W. Schooler, Lost in the sauce: the effects of alcohol on mind wandering. Psychological Science. 20, 747-752 (2009).

6.     M. F. Mason et al. Wandering minds: the default network and stimulus-independent thought. Science. 315, 393-395 (2007).

7.     J. Lehrer, Daydream achiever (2008). Available at (22 May 2010).

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