When you daydream, parts of your brain show sleep-like activity

Our attention is a powerful lens, allowing our brains to pick the relevant details out of the overwhelming flow of information reaching us every second.

However, scientists estimate we spend up to half our waking lives thinking about something other than the task at hand: our minds are wandering. This is striking considering the potential negative consequences, from decreased school or work performance to tragic traffic accidents.

We also know that mind-wandering and lapses of attention are more common when we are sleep-deprived, which suggests they may happen when the neurons in our brain start behaving in a way that resembles sleep. We tested the relationship between sleep and lapses of attention in new research published in Nature Communications.

By monitoring people’s brainwaves against their self-reported states of attention, we found that mind-wandering seems to happen when parts of the brain fall asleep while most of it remains awake.

Local sleep

Directing our attention inwards can be very useful. It can let us focus on our inner thoughts, manipulate abstract concepts, retrieve memories, or discover creative solutions. But the ideal balance between focusing on the outer and inner worlds is hard to strike, and our ability to stay focused on a given task is surprisingly limited.

When we get tired, our control of attention…

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