Ever sit down to focus — maybe on an email, a school assignment, or folding laundry — and suddenly you’re thinking about…what to eat for dinner? Or how dolphins sleep? Or if your ex still follows you on Instagram?

If your brain tends to wander off the second you try to focus, especially if you have ADHD, you might be dealing with a very real, very busy part of your brain called the Default Mode Network, or DMN.

Let’s break down what that means — and why it matters for understanding ADHD.