Why do we even dream?

I know it’s not something new I’m asking here, but why do we actually dream and what’s the benefit of dreaming? Is dreaming maybe a transition phase of our brain developing into a higher intelligence via evolution?
Really, what’s the point of brain “staying up” all night? I mean if all muscles in the body can go to rest during night, why the brain cannot go in “offline” mode and only maintain vital functions (like breathing and keeping body temperature ideal)? Why is the brain active during the night? This seems odd to me. Why evolution didn’t take care of our brain better? Sleeping is primarly resting, isn’t it? Do brain need rest?

I want to hear your opinions… Tnx.

I believe we dream because our brain is developed to create a model of the real world, and during REM sleep we are much less conscious of the real world (although still conscious, of course - that’s why we can be aroused or startled awake), so it starts making a mental model of our inner thoughts and feelings instead.

No one knows!

There are many hypotheses, but no widely accepted theory of dreaming.

Many mammals dream—rats, cats, dogs, pigs, etc.—so humans, as intelligent as we are, aren’t unique in the capacity to dream.

It’s been proposed that lucid dreaming is a sign of mental evolution, but that idea is dampened somewhat by the evidence that humans have been dreaming (or at least seeking trance states) for thousands of years, and by the revelation that different cultures have different levels of lucid dreaming. Among some indigenous cultures, lucid dreaming is far more common than it is in the so-called First World.

Here’s an expert summarizing the knowledge of why we sleep:
ted.com/talks/russell_foster … sleep.html

The need of sleep itself is still a mystery; dreaming is an even bigger one.

A prevailing theory, though, is that dreaming is adaptive—that is, dreams allow animals an opportunity to practice, in a safe virtual environment, for the events of daily life.

A still more popular theory is that dreams foster the integration of memory.

Any attempt, however, to definitely pin down why we dream forces us to fit all our dreaming experience into a box. How can dreaming be practice for future events, or the integration of long-term memory, if a dream is (1) about a past experience—which we remember quite well, or is, perhaps, (2) precognitive?

Dreams come in many shapes. They can be almost ordinary: about us sitting at our desk in our office, with some strange problem; they can be fantastical, like a book or a movie, in which we’re a superhero who can bend time; and, they can be completely incomprehensibly abstract: about you, without a body, flying through a void with geometric colors blossoming around you. And, as I mentioned above, they can apparently be prescient, showing us future events. (A subject that divides many people.)

Aside from the many theories, and the many modes of dreams, however, is a growing body of psychological research that says dreams do indeed offer coherent communication within the psyche. For years—and this is still the general prejudice—people believed that dreams were essentially random. But that’s an outdated idea, disproved by a number of researchers with different aims.

What’s certain is that dreams provide real insight about your body/mind system. This can be as simple as showing you how you actually truly feel about a person, apart from your waking ego’s rationalizations. Or they can simply show us, when we pay attention, what we want or what we’re afraid of. The information isn’t always surprising, or completely unknown to the waking self, but—in my own experience—it’s usually complementary to what I think and feel consciously.

Why we dream is a difficult question to answer. But what dreams offer isn’t difficult to answer at all.

Consolidation of memory.

The brain is meat, too, you know.

So if I understand you correctly you’re saying that when we dream, memory is consolidating itself?
But then why some people dream more intense than the others? Is the intensity of dreaming linear to our brain capacity / memory capacity?

Dreams cannot only be about the consolidation of memory since new experiences are had, and new memories created, in dreams.

Besides, lucid dreaming, which happens quite naturally, puts a damper on the memory consolidation theory. In a lucid dream, you can–to a significant degree, if not to a maximum one–have whatever experience you want. You don’t merely experience a pageant of past memories. Many times, in LDs, and in ordinary dreams, people have experiences unlike anything they’ve experienced before.

Perhaps dream imagery is drawn in piecemeal from past sense memories, with bits of memory assembled into a new-seeming, fantastical, immersive whole, but with consciousness present in many dreams (from “control dreams” to pre-lucid to sub-lucid to semi-lucid–just in those) the process isn’t wholly mechanical.

Also, the recurring nightmares of PTSD sufferers suggest that there’s a problem with the memory consolidation theory. Why can’t the brain consolidate the memories of a traumatic event in one or a few dreams? Why must some people have the same, or almost the same dream, dozens of times? Or for that matter, why do we have recurring dreams at all–sometimes over years–if dreaming is only a consolidation process of recent memories?

I don’t actually doubt that memory integration, or consolidation, is involved in dreaming. Clearly, it is. But, as I wrote above, I think dreaming is more complex than that. It doesn’t easily explain all dreams.

Everybody has a different body chemistry. The intensity of the dream might depend on nutrition, hormones, emotional state allocating more or less concern and memory to a particular event.

It doesn’t explain all dreams, as dreamosis pointed out, but if you ask about the purpose-- well, memory processing, emotional processing, can still play a very big part.

I never said it was a consolidation process of recent memories. It could be a consolidation process of all memories. It could have a more complicated consolidation process with emotional memories, as in the case of PTSD. It could be spontaneously, organically a consolidation process that explains recurring dreams of non-traumatic memories. It could be meta-processing what the brain processes before it creates our experience: the way our eyeballs are shaped turns the world upside-down until the brain corrects it. Perhaps that function is also being processed in the brain during REM sleep.

The feeling of floating or flying, for example, isn’t consolidating the memory of actually flying or floating, or disordering the memory of land travel versus swimming in water. It’s consolidating the memory of walking isolated to movement.

The sensation of floating or flying can also be an active experience, based on the suspension of propioception.

At any rate, does the consolidation theory apply specifically to dreams, or broadly to sleep? What’s the current research? The last I read about it, researchers had linked REM with memory center activity, but it’s important to remember that REM and dreams—while related—do not go hand-in-hand.

I’m agreeing with you—I do think dreams involve memory-processing, but I also think (based on everything I’ve read and experienced) that they’re more complicated than that.

A lucid dream is most certainly a type of dream. We think of them as abnormal (and, statistically, they are, in many cultures) but they involve roughly the same brain activity. A lucid dream features more pre-frontal cortex activity than a non-lucid dream, but again, we ought to remember that scientists cannot easily tell whether a brain is lucid-dreaming or dreaming “normally” without the help of the subject. Why? Because “normal” dreams sometimes have spikes in PFC activity. Also, in the lab, EEGs have shown subjects to be awake (by the standard measures) when the subject had been experiencing himself as lucid in an altered state of consciousness featuring no or little awareness of the body.

But we know from lucid dream research—particularly in regard in PTSD (see Gackenbach’s work)—that dream characters meaningfully communicate with the dreamer. In my own lucid dreams I’ve engaged dream characters and sometimes have gotten useful, and coherent, information back from them. Sometimes, of course, I’ve gotten nonsense; not all DCs are created equal. But all this happens in dreaming. While memory consolidation may be happening in the background, as it were, or may even be reflected in the conscious dream experience, the conversations taking place in LDs aren’t memories. They’re new, present-time experiences.

It’s tempting to draw hard lines between “normal” dreams and lucid dreams, and say that lucid dreams are somehow exceptions to our brain’s nightly routine, but drawing that line isn’t easy. After all, as I said above, researchers cannot definitely tell between a “normal” dream and a lucid dream. (Although they are getting better, with new research focused on the PFC and gamma brain waves.)

But even if we can definitely, biologically distinguish between “normal” dreams and lucid dreams, we still must admit that there’s a big cultural component to dreaming. To wit: some cultures have far more lucid dreams than others. I would expect us to eventually trace this discrepancy to the brain—to physical structures—but I doubt we’re dealing only with genetics. Probably, if I had to guess, we’re dealing with the same types of differences among brains that you see between a group of meditators and a group of non-meditators. You’d see differences that come from how people use their brain, not from the sort of brain they were born with.