Sometimes, my thoughts flow like a never-ending stream of ideas. That is, until someone asks me about the name of a stranger I just met—then, it’s like my brain shuts off completely. This phenomenon, often referred to as “mind blanking,” is surprisingly common. Research suggests that our minds can be blank anywhere from 5 to 20 percent of the time. Neuroscientists are tackling the complexities surrounding this issue, trying to uncover the nature of these empty moments.
Understanding the Blank Mind
Athena Demertzi, a cognitive neuroscientist from the University of Liège, has recently shared insights in a review paper about mind-blanking research. There’s no consensus on what exactly “mind blanking” means; in fact, Demertzi’s paper lists at least seven definitions. Her preferred explanation is that it involves the sensation of lacking thoughts or the inability to articulate any that may exist.
This broad definition allows for various ways people might describe their experience of a blank mind. Phrases like “I can’t recall what I was just thinking” or “I was zoning out” are common. Demertzi notes that this vagueness can present challenges for researchers hoping to study related brain processes, such as memory.
Within her expansive definition, Demertzi attempts to distinguish different types of mind blanking. It’s a complicated task. One reliable method for examining brain activity is functional magnetic resonance imaging (fMRI). Demertzi explains that researchers often tell participants to “think of nothing” while in the scanner, which generates activity in brain regions like the cingulate cortex. However, this doesn’t actually indicate a blank mind but rather highlights the cognitive effort involved in suppressing thoughts.
Signals Behind Mind Blanking
To explore this further, Demertzi used a different approach in a 2023 study. Her team monitored participants’ brains at rest while intermittently asking them to describe their thoughts. They discovered that those who reported mind blanking exhibited a unique signal—characterized by a temporary synchronization of brain networks. “They are all deactivated,” she notes. Interestingly, this same signal can also be observed during sleep or anesthesia.
This finding aligns with other research identifying a strong connection between mind blanking and the brain’s arousal level. When stimulation is low, episodes of mind blanking are more prevalent, as higher arousal appears necessary for maintaining an ongoing stream of thought.
But, there seems to be a trade-off. An excessively heightened state of arousal can lead to anxiety, which in turn may hinder performance. Demertzi points out that anxiety often manifests as racing thoughts, complicating the ability to recall individual ideas and contributing to another form of mind blanking.
Mind Blanking and ADHD
In some instances, mind blanking can be linked to clinical conditions. “We know it appears in clinical states like ADHD,” says Demertzi. Research indicates that unmedicated children with ADHD report mind blanking more frequently compared to their peers. Other conditions, like generalized anxiety disorder, also show related episodes of mind blanking.
The crux of Demertzi’s inquiry is understanding why mind blanking occurs in the first place. While researchers are still piecing it together, she speculates that its connection to sleep and arousal might offer clues. “When we sleep,” she explains, “our neurons rest by clearing out excess information accumulated throughout the day via the glymphatic system.”
Demertzi suggests that this toxin-clearing process—though debated among sleep researchers—might also happen briefly while we’re awake. We experience these “pit stops” in cognition as moments of mind blanking. Ultimately, they may serve as a mechanism for our brains to keep functioning smoothly throughout our waking lives. “How can we sustain a continuous wakeful life if our brains aren’t helping us out a bit?” she questions.
