Lost in Our Thoughts

by Farzana Zane

art by Jennifer (Ruiqi) Wang

 A stuttering, incessant chime rings through my ears. I groan and put forth the smallest trace of energy to turn my alarm off. In the fleeting moments between sleep and wake, I remain still as the last remnants of my dream vanish. And then it hits me. Assignments. Emails. Deadlines. With a deep chested sigh, I pull myself up and out of bed and begin mechanically moving around. As the drowsiness seeps out of my body, my mind starts listing my tasks for the day: study for the bio test, finish that reading by tonight, and start my lab report. A dull sense of dread settles in the pit of my stomach, as I realize the list continues to grow by the second.

Our stream of consciousness often drifts, slipping between the hazy moments of our dreams and the waking reality that demands direction. In sleep, our mind walks freely, producing vivid fantasies, but as we wake, it is almost as if our consciousness needs something to hold onto, a goal or task, to push ourselves out of bed and begin the day.

Our consciousness is the overall awareness of our self (internal) and our environment (external), and is often described as a balance between the two, both of which change depending on our state of mind. For example, when awake, our brain utilizes both external and internal stimuli to become highly aware, linking sensory perception to individual life experiences [1]. However, during sleep, varying levels of internal awareness combined with low external awareness, supports dream-like experiences [2].

Yet, consciousness is not just limited to being asleep or being fully awake [3]. For a long time, research on human cognition has focused on understanding waking consciousness during goal-directed tasks, reflecting society's importance for productivity and achievement. But our time awake is not always spent focusing. The in-between moments of our life, where we find ourselves to be “lost in thought” – staring out the window during a lecture or that trace-like feeling when you're driving and suddenly realize you don't remember the last couple of minutes – are far more common than we might expect. In fact, this phenomenon, referred to as daydreaming, occupies approximately 30% to 50% of our waking minutes [3].

Daydreaming is a distinct state of consciousness that describes an intermediate state between wakefulness and sleep. It is used to describe self-generated internal thoughts or mental experiences that arise independently of immediate external sensory input [3]. These thoughts can occur as a distraction from a main goal/task, referred to as task-unrelated thoughts, or can also occur when a person is unoccupied with a task, referred to as a resting awake or idle state [4]. Sometimes, these thoughts interrupt a task, pulling our attention, and other times, they emerge when there is nothing demanding our attention.

In the scientific community, the dominant term used to describe the process of generating internal thoughts was mainly “daydreaming.” Most recently, it has become “mind-wandering (MW)” [4].  Recent research from Dr. Shimoni and Dr. Axelrod found a slight difference in the participant perception of these terms: mind-wandering was perceived as a mental process involving another activity/task and consisted of planning, worrying, and ruminating thoughts, while daydreaming was perceived as more independent and done during resting wake periods associated with more fantasizing thoughts. Throughout this article, I will use mind-wadering (MW), as an interchangeable term to daydreaming. Such thought processes in moments where we experience MW can feel fleeting, unintentional, spontaneous, providing a brief mental escape for your mind [4].

Circle of Attention: The Cognitive Mechanisms of Daydreaming My fingers swipe up and down the trackpad, with eyes lazily gazing at the words on the screen. The glow of the computer stares back, almost angry with its brightness. I glance at the time: 12:21 am.  The same sentence is read again and again, until slowly the words begin to blur, and the light softens at the edges. A myriad of thoughts invade my head: a test next week, an empty stomach, another unanswered email, and on top of that a pile-up of new messages. The thoughts arrive all at once, scattered and uninvited. And just as quickly, the glare of the screen pulls my focus back into reality. 

Even as MW occupies a large portion of our time awake, we are often not fully aware of when it occurs, creating this helpless feeling of being “lost” in our thoughts. While most people have an intuitive sense of what daydreaming is, understanding its physical manifestation makes it easier to notice it in ourselves. Essentially, MW reflects the cyclic exchange of two core mental processes: perceptual decoupling and meta-awareness [5].

Perceptual decoupling is the brain’s ability to “decouple” or sever attention from external sensory input to focus on internal thoughts [5]. Research has shown that attention, or selective conscious concentration, directed towards external objects via perceptual input (light, sound, smell, taste, and touch) leads to interaction, thus named perceptual-action coupling [5]. This implies that generated thoughts are “coupled” or associated with simultaneous input. Our thoughts are directly tied to what we are sensing. An intuitive example might occur when you are sitting in a lecture, and suddenly your name is being called. Instantly, your body responds to the sound and turns your head towards it. However, during MW, internally generated thoughts are disengaged from the perceptual input, implying that while your brain is still receiving external input (i.e., what your eyes are seeing), your attention is no longer centered on it. For example, during reading, oftentimes we tend to zone out, but our eyes will still continue tracing the words. During this, our thoughts are generated from cortical regions that are decoupled from regions of visual input [6].

This shift does not always go unnoticed by us. At some point, there is a moment of realization, a sudden “Oh” feeling. This is where meta-awareness is seen. Meta-awareness is the ability to recognize the current state of consciousness, allowing us to acknowledge that focus was elsewhere and bring back attention into the current task [7]. Essentially, our conscious mind is redirected back into reality from our MW state via meta-awareness. It becomes the gap that prevents our minds from being fully invested and consumed by our internal thoughts.

Neurobiological Mechanisms of Daydreaming

With a clearer picture of how daydreaming manifests in everyone, even ourselves, its underlying mechanisms become startlingly less obvious. It brings to light the question of what actually triggers the act of perceptual decoupling, and are all mind-wandering thoughts completely random? 

Questions such as these are speculated by scientists and philosophers alike, and many believe it is a mental escape during boring life tasks or a coping mechanism for times of distress [8]. These assumptions can be further supported by underlying neurobiological mechanisms.

Default Mode Network (DMN): The Not-So-Idle Brain

My eyes continue to wander over the words on the screen. But slowly, the words begin to blur and the meaning slips from my mind.

As discussed, perceptual decoupling shifts attention away from our immediate environment and towards internal thought. Rather than completely fending off sensory input, the brain continues to receive it, but our attention is no longer directed towards it.

This cognitive process is supported by specific neural systems in the brain [9]. In this state, specific cortical regions, known as the Default Mode Network (DMN) become more metabolically active. The DMN is known to have a core that is insulated from sensory stimuli, thus allowing internally generated thoughts to take more priority [9]. Simultaneously, cortical regions involved in sensory processing (i.e. somatosensory, visual, and auditory cortex) become less active, allowing MW episodes without being interrupted by immediate environmental stimuli [6].

In a neurological sense, perceptual decoupling is not simply triggered by boredom, but more by an increase in demand for internal thought and decrease for sensory stimuli [6]. To clarify, internally generated thoughts demand more attention by becoming more engaging, requiring more energy to procure. In contrast, the environment demands less attention, as the external stimuli comes to a point where it becomes unstimulating, or in other words unable to produce a response. As a result, perceptual decoupling results in DMN activation, supporting internally generated thoughts [6].

The discovery of the DMN comes from early studies of cerebral blood flow [6]. Brain physiologist David Ignvar found that frontal lobe activity had reached high levels during rest states. In understanding that the frontal lobe mainly facilitates executive functions such as planning, decision-making, and attention, this discovery established the very foundation of MW: brain activity continues in the absence of an external task and is not truly idle when left undirected [9].

Moreover, a study led by Kalina Christoff, demonstrated that with the simultaneous use of fMRI and experience sampling, an assessment using real-time data on individuals’ thoughts, feelings, and behaviors, MW can be explored in detail [9]. fMRI findings suggested that mind wandering was associated with the activation of the medial prefrontal cortex (mPFC) and posterior cingulate cortex (PCC), which are now key regions of the default network [9]. The PCC acts as the primary “hub” or interconnection between the DMN and other networks in the brain to allocate where the attention streamlines [10]. The PPC is believed to mediate the disengagement of attention and the reorientation of salient information, all while being insulated by environmental stimuli. The mPFC facilitates and likely contributes to the contents of these internal thoughts (self-referential, future-orientated, etc), further drawing attention inward [11, 12]. With the combination of PCC, which allocates where attention streamlines and mPFC facilitating attention inward, both function as the core of the DMN [13].

Sharp-Wave Ripples (SWR): Replay During Rest

She was saying something about the concert on the 5th…Oh, I should email my professor about this…do I have homework for this class…?

Knowing the exact details of your daydreams can be difficult, as they vanish once our attention is redirected. But in the rare moments you catch yourself midst daydreaming, your thoughts might feel like a series of “replays.”

The fragments of our recent experiences – the last words exchanged with a friend, a professor's reminder about homework, or even the unanswered email notification – all form a seemingly random chain of thought until our attention is pulled back.

This replay is aligned with a broader network within the DMN. While the PCC and mPFC serve as the core of the DMN, regions such as the parahippocampal cortex and the medial temporal lobe (MTL), explain how the brain begins to replay memories during daydreams [13].  

The function of the MTL within the DMN was discovered from an analysis conducted to measure the relationship between the structural organization of the brain (cortical thickness) and patterns of human experience [14]. A 2019 study wanted to determine if the cortical structure in DMN regions correlated more with “off-task” thoughts or “on-task thoughts”, while off-task thoughts were associated with more vivid internally generated thoughts (MW). It was concluded that the cortical thickness in different regions of the parahippocampus was associated with distinct patterns of thought. The anterior parahippocampus was linked to more task-focused thinking, while the posterior region was associated with thoughts that had more vivid subjective detail (off-task thoughts). Both of these regions fall into the MTL, a subset of the DMN that processes long-term and recognition memory. These functional differences imply that the MTL and DMN construct a broad network that contributes to MW, highlighting the involvement of the hippocampus and its memory consolidation in self-generated thoughts [14].

Building on this established relationship, MW has been linked to the emergence of the sharp-wave ripples (SWRs) in the hippocampus [15]. An observed increase in the DMN fMRI signal following SWRs, but not following any other hippocampal electrophysiological events highlights the close connection between DMN and hippocampal SWRs. SWRs are bursts of synchronized neuronal activity that vary depending on the state of the animal (sleep, idle, active). During sleep, SWRs support early stages of memory consolidation, a process by which a temporary memory remodels into a more stable, long-term memory. For the establishment of long-term memories, the hippocampus acts as the initial “library” of recently encoded experiences. Through the repetition and reactivation of neural activity associated with recent experiences, the connections between neurons strengthen, and these permanent memories develop in distributed regions of the neocortex, the outermost layer of the brain responsible for cognitive thinking managing complex behaviors. Storing memories in the neocortex reduces the need to retrieve them from the hippocampus [15]. During awake periods, SWRs are believed to aid memory retrieval and use past experiences to guide decision-making with high levels of SWRs seen during rest (i.e motionless) [16, 17].

Reactivation is specifically coordinated by hippocampal SWRs [18]. After a new learning experience, large SWRs selectively promote enhanced memory activation in the hippocampus and PFC during sleep. A large SWR is implied to be larger in amplitude and in duration, meaning that the larger and longer SWRs are, the more effective their association with memory coherence is, strengthening memories by converting short-term memories to long-term. The hippocampal SWR synchronizes with the timing of local PFC neurons allowing previously active neurons (involved in learning and experience) to reactivate, strengthening the memory [18]. In simpler words, SWRs allow the brain to “replay” recent experiences, reinforcing them into lasting memories, hence why it appears in our daydreams and our dreams.

A study in 2023 recorded SWRs from the hippocampus of 10 patients with epilepsy for 15 days [19]. Findings showed that SWR rate increased during the night, exhibiting intense rate fluctuations and a decrease upon waking. SWR rates also decreased at scheduled mealtimes and were higher during the leisure times (i.e afternoon). The timing of the SWR increases imply that it occurs during moments of the day where there is idle time, or time to “zone off”. Essentially, findings concluded a correlation between SWR and the ongoing content of self-generated thoughts, highly proposing an association with the activation of MW episodes [19].

Neuromodulation of SWRs: Driving Force of Daydreams

The frustration from the assignment lingers, but something else comes along…a small moment from earlier:“You look really pretty today.” A smile starts unfolding as the memory replays, almost as if I am desperate to hold on that same feeling.

At first glance, these “replays” seem entirely random, but a further look into the neuromodulation of SWRs suggests that they are tied to specific memories [20]. Neurotransmitters, chemical messengers that regulate mood, emotion, and behavior, have been seen to modulate SWRs. Dopamine, a neurotransmitter released during pleasurable or rewarding events, is positively correlated with SWR activity [20]. This relationship suggests that our replays are not random, but biased towards experiences that were meaningful or rewarding to us. It is likely MW occurs to possibly procure this dopamine boost, subtly reinforcing a need for offline states such as rest or sleep. Moreover, this suggests a distinction between MW and daydreaming, with daydreaming potentially involving more “replays” driven by rewarding experiences [4].

Locked into the same sentence once more, the words begin to lose meaning. It feels as though my eyes blink slower and a sluggish haze settles in. I began thinking of moments from earlier, desperate for something – anything! – to escape this dullness.

In contrast, norepinephrine, a neurotransmitter associated with alertness and focused attention, appears to have a negative correlation with SWR rates [21]. Increased levels of norepinephrine are seen with a coinciding suppression of SWR, suggesting that heightened focus reduces internally generated thoughts, further supporting the notion that SWR is involved in mind-wandering [21]. In other words, when focus diminishes, the brain becomes more inclined to MW. Such information implicates another reason as to why we daydream: to alleviate boredom from lack of focus on external tasks.

Aftereffects of Daydreaming

Entirely frustrated at myself, I close my computer and let the consequences of leaving the assignment wash over me. I grab my headphones, and soon enough I find myself pacing around the room. The beats of the music and my steps slowly ground me, vanishing the remnants of my anxiety. My thoughts slowly drift into a world of my own, a world where there's a different me…a better me? Mouthing words and smiling at myself, the new fantasy slowly brightens my night.

Daydreaming allows the brain to disengage attention from the immediate environment and explore internally generated thoughts [22]. In this state, different ideas, memories, and experiences can lead to novel creative connections. At the same time, the selective replay of memories can allow individuals to stimulate future scenarios to make more upcoming informed decisions. Nevertheless, the positive effects of daydreaming, creative problem solving and future decision making, can dwindle after daydreaming reaches excessive levels of intensity [22].

Once there is a reduction in one's ability to regulate consciousness back to a goal-derived state, also referred to as a reduction in the meta-awareness of our episodes, MW becomes associated with a greater psychopathology and disruption to functioning [23]. Through several studies that attempted to differentiate normal and abnormal daydreaming by testing the association of daydreaming with other clinical symptoms, it became gradually evident that daydreaming can sometimes evolve into an extreme and maladaptive behavior, up to a point where it becomes clinically significant [23, 24].

First defined by Dr. Eli Somer, Maladaptive Daydreaming (MD) is an immersive imagination activity that replaces human interaction and interferes with academic, interpersonal, and/or occupational functioning [23]. His work has made it clear that MD is a unique disorder that varies from person to person. Each person’s specific experiences contribute to differences in content and motivation. Although this disorder varies in experienced symptoms, there are a few common findings. Some unique features that differentiate MD from normal daydreaming follow: daydreaming is neither very immersive nor fanciful, but MD seems to represent an innate talent for vivid fantasy. Fantasy is defined as a fictional tale created by a subject for his own pleasure and no other purpose [23]. Additionally, there is a requirement for additional stimulation, especially repetitive and or stereotypic kinesthetic activity along with exposure to evocative music to facilitate this mental activity [24].

MD became more prevalent during the COVID-19 lockdown, where daydreaming became people’s emotional escape from reality; essentially becoming more intense and frequent for those who were constantly stressed [25]. A study conducted in 2021 examined the Italian population who were maladaptive dreamers during the COVID-19 lockdown. The study reported that MD severely correlates with all ranges of depression, anxiety, and increases online relationships; further limiting face-to-face interactions and inducing MD to escape reality. While daydreaming is a relatively normal experience, MD becomes the infatuation of fantasies and abnormal thoughts, which is heavily correlated with mild to severe mental health disorders such as depression and anxiety. As the COVID-19 lockdown limited physical social interactions, it also created space for anxious and stressed individuals to desire to escape their reality and redirect their focus to extreme, voluntary, dysfunctional thoughts. The additive nature of MD is exceedingly dangerous, as it causes the individual to lose sight of reality due to these intense compulsive thoughts. [25]

Implications of Daydreaming

Pausing the music, I realize it’s almost been an hour since I started pacing around. I pull my headphones out and let the silence of the room ring. My laptop sits on the table, the same sentence waiting where I left it. A second passes, and then another…“It's just another stupid assignment.” The decision to stop comes easier than expected. I turn off the light and slip into bed, and once again, I find my thoughts blurring…drifting until sleep takes me. 

Our consciousness exists on a spectrum, constantly shifting between our internal and external awareness of the world. Daydreaming is only one state within this spectrum, and yet it occupies far more of our lives than we realize. It occurs as our brain unhooks its attention from our immediate surroundings and redirects it inward, engaging cortical regions such as the DMN to form a streamline of internal thoughts. This is not just another unfamiliar neurological mechanism, it is an inherent part of being human. 

The inside of our minds demand attention, pulling us away without warning. At times, this can feel comforting especially when society's demands grow heavier. But that same comfort can slip away once the drift begins to control us rather than simply passing through. By understanding both the nature and the subsequent actions of daydreaming, we can begin to reclaim agency over our consciousness.

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