The human brain uses that tiny moment of shut-eye to power down, researchers from Japan's Osaka University found.
In a new study, they found that the mental break can last anywhere from a split second to a few seconds before attention is fully restored, the 'Daily Mail' reported.
Scans that track the ebb and flow of blood within the brain revealed that regions associated with paying close attention momentarily go offline.
The brain then goes into a 'default mode network', or idle setting.
The same setting is engaged when our attention is not required by a cognitive task such as reading or speaking and our thoughts wander freely.
During this mode people tend to contemplate their feelings; they wonder what a friend meant by a recent comment; they consider something they did last week, or imagine what they'll do tomorrow.
While listening to another person or reading, that usually comes at the end of a sentence and while watching a film, people are most likely to blink when an actor leaves the scene or when the camera shifts.
Most people take between 15 and 20 such moments of downtime per minute.
Researchers studied 20 healthy young subjects in a brain scanner as they watched snippets from the British comedy Mr Bean.
When subjects blinked, the researchers detected a momentary stand-down within the brain's visual cortex and somatosensory cortex - both involved with processing visual stimuli - and in areas that govern attention.
Separate studies on blinking have shown that while telling a lie, people have been found to blink less.
In the seconds after telling a lie, however, the liar will blink far more frequently than a truth-teller.
The new research was published in the journal Proceedings of the National Academies of Science.
