Why Do We Dream?

If I'm asleep and the room is quiet, why can my brain make up a whole story? What's going on?

Sleep isn't the brain going blank. It keeps working with memories, feelings, and things you've noticed. A dream can arise from that activity. But that helps explain how a dream happens, not whether the story has a job to do.

So the story is my brain sorting the day?

Maybe, though “sorting” sounds tidier than what we know. Dreams can borrow from today and from long ago without replaying either. Imagine you're worried about catching a bus to an important appointment tomorrow. That's the situation before sleep.

Then I dream I miss the bus?

You could. Or the bus pulls up at your old school, and you're trying to find the appointment inside. That didn't happen, and it doesn't need to make sense. The worry about getting somewhere has gotten tangled up with another familiar place.

Why the school in particular?

Usually we can't tell. School might have some older association for you, but assigning it a specific secret meaning would be guessing.

So I'd pay more attention to the worry than try to decode the school?

In this example, you already know you're worried about the appointment. The dream might echo that. What's striking is that you can feel genuinely anxious about an impossible bus-to-school trip while you're asleep. It may not set off your usual “wait, this makes no sense” alarm until you wake up.

The feeling can be real even if the scene isn't. Does feeling it help with the worry?

Possibly, but we can't say that's what this particular dream was for. Sleep helps with some kinds of memory, and there's evidence it's involved in handling emotion. The harder question is what the dream itself adds. That bus story could help in some way, or it could come along while the sleeping brain does other work.

So the bus story might not be doing any work?

It might not. We don't yet know whether a particular dream helps with that work or just reflects it.

If I wake up remembering the school, maybe I check the bus schedule instead of treating the dream as a warning?

If you're worried about being late, yes. The dream might tell you that the appointment was on your mind, but it can't tell you what tomorrow's bus will do. The schedule can at least help you plan.