Why dreams feel real while you are in them

Inside a dream, absurdities pass without comment. Your dead grandmother is in your office, you are late for an exam at a school you left twenty years ago, and none of it raises a question.

The leading account

Neuroimaging shows reduced activity in dorsolateral prefrontal regions during REM: areas associated with critical judgement, working memory and self-monitoring. Meanwhile limbic and visual regions are highly active.

So you get vivid imagery and strong emotion, with the faculty that would normally say hang on running at reduced capacity.

The evidence from the other direction

Lucid dreaming supports this. When people become lucid, when the critical faculty comes back online mid-dream, frontal activity increases. Lucidity looks, neurologically, like recovering some of that judgement without waking.

What this means practically

It is why reality checks work. You are not trying to spot something impossible; impossible things are everywhere. You are trying to build a habit strong enough to run without the faculty that would normally prompt it.

It is also why dream bizarreness is not evidence of anything meaningful. The strangeness is the medium, not the message.