You know when someone spaces out for a second, and you can’t get their attention? “What are you thinking about?” prompts a response of “Nothing,” which you figure is a euphemism for private thoughts. Historically, consciousness has been assumed to be continuous when you’re awake, flowing between a focus on external things and internal thoughts as your mind wanders. But a new study in PNAS suggests that parts of our brain may actually be taking a nap during those thinking-about-nothing moments.
“Mind blanking is defined as the complete absence of mental content that can be described to others. No mental images, no catchy tune looping in your head, no obsessive thoughts... nothing!” explained Sorbonne University study author and neurologist Esteban Munoz-Musat in a statement.
Noting that mind blanking was associated with certain psychiatric conditions, including anxiety disorders and maybe ADHD, Munoz-Musat and colleagues from the Sorbonne and Monash University in Australia, set out to determine whether it reflected detectable changes in the brain. They used high-density EEGs to record the brain activity of 62 healthy volunteers as they completed a tedious task in a dimly lit room for one hour and 40 minutes. Volunteers were interrupted at random intervals and asked to report on their mental states: thinking about the task, thinking about something else, or thinking about nothing at all, i.e., mind blanking.
Read more: “Why Did That Come to Mind?”
The results showed that the episodes of mind blanking described by participants corresponded with detectable changes in their neurophysiology. Sharing of information between more distant parts of the cerebral cortex was disrupted. Neural representations of external stimuli, such as sights and sounds, were significantly reduced. Some of the typical signals of conscious access to information were suspended.
“These observations suggest that during a mind blanking episode, participants had reduced access to sensory information from their environment,” said Sorbonne University neurocognitive researcher Thomas Andrillon, senior author of the study, in a statement.
Basically, being awake doesn’t guarantee that you’re thinking about anything. You may experience intervals where certain parts of the brain take a nap in what the researchers referred to as “neural silencing”.
Mind blanking is common, varying between individuals from as little as five percent of our waking hours to as much as 20 percent. The study authors wrote that “while puzzling, this [content-free] perspective would bring even more value to those precious moments of conscious experience.”
In other words, make the best of your alert waking moments. 
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Lead image: fran_kie / Shutterstock
