I have long had interest in dreaming, and one of the defining features of ordinary dreams is that the dreamer either accepts the dream as "real life", or does not question the surroundings.

Compare these ordinary dreams with "lucid dreams", or conscious dreaming, where the person is aware of the fact that he/she is dreaming. Within an ordinary dream, a person "goes with the flow", while within a lucid dream, the person can think clearly and act voluntarily without waking up.

Have these been any studies that used fMRI or other techniques to try to determine what is it within the human brain that causes the distinction between conscious and ordinary dreaming?

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    $\begingroup$ I think from a practical perspective it's difficult to get someone into a comfortable sound sleep in an MRI machine. $\endgroup$ Feb 7, 2013 at 4:28
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    $\begingroup$ [I'm perhaps in the minority here.] I had thought the title meant "What causes people to accept recalled dreams as reality?" until the description of the question cleared that up for me. Nothing in the title presently indicates or implies that the acceptance occurs during the dream. Maybe rephrase the question "What causes dreaming people to accept their dream as reality?" or "What prevents dreaming people from wondering if they're dreaming?" $\endgroup$
    – John Pick
    Feb 7, 2013 at 22:30

3 Answers 3


If you are searching specific part of the brain, I think that frontal regions of cortex will be an answer(In particular, the dorsolateral prefrontal cortex which was associated with self-focused metacognitive evaluation). But, as it common in real life, becoming aware of dreaming state required coordinated work of different parts of brain. You can read this very good article and wiki of course.

Lucid dreaming is characterized by a regaining of higher cognitive capabilities, eventually leading to the awareness of the dreaming state. Recent quantitative EEG data have shown that this wake-like intellectual clarity is paralleled by neural activations in frontal and frontolateral regions. Likewise, PET data show cognitive control in dreams to be associated with activation of frontal cortex components. via

  • $\begingroup$ Also this article is interesting $\endgroup$
    – sviter
    Feb 7, 2013 at 18:35
  • $\begingroup$ Great link. From the article: " During lucid dreaming the bilateral precuneus, cuneus, parietal lobules, and prefrontal and occipito-temporal cortices activated strongly as compared with non-lucid REM sleep." $\endgroup$
    – Alex Stone
    Feb 9, 2013 at 5:13

Probably just a part of the story, but the locus coeruleus is known to be implied in the wake-sleep cycle.

Furthermore, an experiment on cats demonstrated that removing this structure cause actual (but nonsensical) behaviors replacing normal REM sleep phases: cats have no more REM sleep and instead hunt non-existing rats (or something else who knows).


However, that does not mean that people with confusion have a lesion of this this structure.


The key method to induce lucid dreams (and I speak of personal experience here) is to train yourself to regularly doubt the "realness" of your environment. F.x. by occasionally just stopping what you are doing and wondering about what makes you so sure that this is not a dream actually ...

This new habit also becomes part of your dream self (personally I think that there is no psychological difference between awake and dream personality - which is why this trick works in the first place).

So the reason why you accept a dream as real is pretty much the same reason why you accept reality as real. It's just a human tendency to accept the perceived environment.

In the book "The Man Who Mistook his Wife for a Hat" a stroke patient is described who tried to throw his leg out of his bed b/c due to the stroke the perception of his body was impaired in such a way that his leg no longer seemed to belong to him. Even though logical reasoning makes it highly implausible that somebody would put a leg into his bed - he accepted his perception as real - period.

There are plenty of examples and experiments of this kind - essentially the human tendency to simply accept perception is very strong. That's why you also accept the dream as real - until you get used to doubting realness and lift yourself into a metaposition from which you can judge logically and infer from the fact that you just shaked hand with Santa Claus that something weird is happening.

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    $\begingroup$ I upvoted this answer. I think it is the best answer and satisfactory. It's hard to believe it didn't get the highest score. Maybe it's not quite absolutely complete but that's okay. If seeing what appears as the real world doesn't mean it actually is 100%, why don't we doubt that we're in the real world when we are all the time? $\endgroup$
    – Timothy
    Aug 31, 2022 at 20:21

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