What a Day for a Daydream

Sit there. Don’t do anything. What happens? Does your mind start to wander—toward the future, or back into the past? Do memories pop up? Do you start imagining what others might be thinking about you? If so, that’s several connected regions of your brain working together to form what’s called the Default Mode Network.

The Default Mode Network is a relatively new discovery, and scientists are still mapping out all the brain areas involved and what each part does. Current understanding suggests that it’s primarily housed in the prefrontal cortex, with deeper connections to regions like the thalamus, amygdala, and cerebellum, as well as the cingulate cortex and parietal lobe. Interestingly, researchers stumbled upon it because they noticed increased blood flow to these areas when people were supposedly at “rest,” a finding made possible through fMRI scans.

When your mind is at rest, the Default Mode Network kicks in. Your thoughts wander, and that familiar mental chatter makes itself known. But as soon as you begin a goal-directed task, the Default Mode Network “deactivates” while something called the Salience Network activates. Blood flow shifts away from the Default Mode Network and moves to the regions needed for the job at hand.

Its full range of functions is still being uncovered. Broadly, the Default Mode Network helps us make sense of the world by drawing on past experiences to plan for the future. It may also help us imagine others’ perspectives. Newer research suggests it plays a role in consolidating memories at rest (by replaying experiences), and in building our internal narrative and sense of self. And that mind-wandering? It can spark creativity. Those “shower ideas” you get? That’s your Default Mode Network working, right alongside your shampoo keeping your scalp dandruff-free.

But like anything in the body, too much Default Mode Network activity can be a problem. It’s thought to play a significant role in depression, becoming overactive when it shouldn’t be. This may explain why people with depression ruminate and struggle to break free from certain thoughts. Dysfunction in the Default Mode Network is also linked to bipolar disorder, anxiety, ADHD, and even Alzheimer’s disease, though more research is needed.

The good news? Simple techniques can help calm an overactive Default Mode Network. Cognitive Behavioral Therapy, mindfulness, and meditation have all been shown not only to slow the network down but also to help rewire the neuronal connections involved. There’s even emerging evidence that some antidepressants, like SSRIs, can help restore healthier patterns. And since the Default Mode Network doesn’t fully develop until late childhood, cooling it off can give you something unexpectedly refreshing: a child-like openness to the world again.