[HN Gopher] Why do we dream? A new theory on how it protects our...
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       Why do we dream? A new theory on how it protects our brains
        
       Author : jdnier
       Score  : 233 points
       Date   : 2020-12-31 05:59 UTC (1 days ago)
        
 (HTM) web link (time.com)
 (TXT) w3m dump (time.com)
        
       | nerfhammer wrote:
       | maybe firing random neurons keeps the connections alive
        
         | vyrotek wrote:
         | A sort of "Chaos Monkey" for the brain.
        
       | starpilot wrote:
       | So does melatonin give enhanced brain benefits since it leads to
       | vivid dreams?
        
       | FailMore wrote:
       | This idea ignores a fascinating aspect of REM sleep. During REM,
       | the brain shuts down the executive functions, while the brain
       | goes into extreme 'story generation mode'. A story in which you
       | are a character. I think this is one of the most overlooked and
       | interesting parts of dreaming. We are able to observe ourselves
       | in our dreams acting without the constraints of our 'executive
       | functioning' brain. This means we get to learn about our purely
       | emotional behaviour, and perhaps spot where it is maladaptive. (I
       | am very bias on this subject, as I have written a paper on this
       | topic - https://psyarxiv.com/k6trz, which was discussed here
       | https://news.ycombinator.com/item?id=19143590)
        
         | bonoboTP wrote:
         | I definitely feel like I have "executive function" even in many
         | non-lucid dreams. It's just that I assume it's reality but I'm
         | still solving problems, fighting, running away, talking to
         | people to achieve things. Yes the world changes in weird ways
         | and the distinctive thing about dreams is not noticing that
         | this level of weirdness is implausible.
         | 
         | But I'm distinctly not "purely emotional" or animalistic in my
         | dreams.
        
         | majkinetor wrote:
         | You sound like its a fact, while its just one interpretation.
         | 
         | The idea also doesn't ignore REM sleep like you claim.
         | 
         | > This means we get to learn about our purely emotional
         | behaviour, and perhaps spot where it is maladaptive.
         | 
         | How did you get this ? Its another interpretation of available
         | data. Extreme story generation mode may not be end goal but
         | artifact.
        
           | vinay_ys wrote:
           | It may not even be a 'mode' as such.
        
         | agumonkey wrote:
         | Makes me wonder when did animals started to dream, even
         | prototypcally.
         | 
         | Mammals ? Reptiles ?
        
         | sundarurfriend wrote:
         | I think the article describes _one_ good reason for why we
         | dream, one of the benefits of dreaming, but it doesn 't have to
         | be the only or even main reason. I think it's most likely that
         | dreaming provides multiple benefits, and what the article
         | claims is one of the minor ones.
        
       | zoomablemind wrote:
       | I understand that current theories link dreaming to REM phase of
       | the sleep. That is when we are in REM phase, we dream. Yet,
       | remembering of the dreaming is not always guaranteed. So it's
       | very much possible to have the REM phase, but no recollection of
       | having dreamt at all. The data on dreams is likely based on self-
       | reports, unlike the REM data which can be measured. So there's a
       | lot of room for speculation on any possible connection and
       | purpose of the dreaming.
       | 
       | On thing is for sure, if we can say to remember of the dreaming,
       | we indeed did wake up.
       | 
       | In personal experience, I noticed a direct connection between
       | physiological discomfort while sleeping and the related dreaming.
       | That is a discomfort, say in my body positioning would generate
       | dreams around the effect of it, not always literal but often it
       | would either trigger a brief awakening or a change of the
       | positioning.
       | 
       | One very stark experience was related to a case when previously
       | frozen (and likely swollen at night) toes were constantly
       | triggering a dream of sleeping next to a campfire and leading
       | invariably to waking up with my knees bent and feet tucked
       | underneath me. Toes healed, the dream was gone.
       | 
       | Another very much reliable trigger is airsupply. Say, by odd
       | positioning the breathing is affected, sometimes an external
       | factor can affect the air quality. Sure enough, there will be
       | some dream leading to waking up just to be annoyed at dry/stuffy
       | nose or some random smoke from an open window finding its way in.
       | That I should feel probably grateful about, as it's like an
       | internal smoke alarm... (though no substitute for proper
       | detectors!!)
       | 
       | The point is, the dreaming might still be an extension of our
       | survival mechanism. Kind of internal dashboard to check while
       | asleep, no matter how oddly scripted.
        
       | time0ut wrote:
       | My personal experience has been that dreams seem to play a
       | critical role in learning. Often when learning something new, the
       | new experience will manifest in my dreams. The more immersive the
       | new experience, the more rapidly the dreams come and the more
       | vivid they are. Most dreams that I remember are almost like
       | mashups of previous experiences. Very often, my dreams have
       | elements of places and experiences from my childhood. I could see
       | this being a manifestation of the brain managing placticity.
       | Perhaps the brain grounds itself in old experiences and mixes in
       | new ones so that things are not forgotten.
        
       | noncoml wrote:
       | Dreaming is practicing our survival skills in a safe environment.
       | Nature's "VR", if you want.
       | 
       | Reference: Why else am I running naked in the supermarket?
        
         | Daub wrote:
         | "Dreaming is practicing our survival skills in a safe
         | environment. Nature's "VR", if you want"
         | 
         | This also sounds like a rationale for play. A safe practice
         | zone... a sand box.
        
       | spicyramen wrote:
       | One of the few serious books about dream meaning is from Freud
       | https://g.co/kgs/LdLZs8 this field is seen as pseudo-science but
       | I believe we still have a lot to discover
        
       | newdude116 wrote:
       | Since even my dog dreams, it must be something very fundamental.
        
       | Roritharr wrote:
       | My wife is having really bad sleep problems which she attributes
       | to dreaming too much too intensely. She just doesn't seem to get
       | rested doing this.
       | 
       | This article sadly does not give a clue what could be her
       | problem.
        
         | raducu wrote:
         | My wife is exactly like this.
         | 
         | She says she feels tired because she feels she lives paralel
         | lifes in her sleep.
         | 
         | But objectively she has NONE of the symptoms of bad sleep I get
         | when I can't actually sleep.
         | 
         | So she maybe just feels emotionally tired for the first 5
         | minutes after she wakes up.
         | 
         | I once gave her my fitbit and checked her sleep -- she had
         | almost no restless sleep like I do, she had a lot of REM and a
         | lot of deep sleep, I'd love to have her sleep pattern.
        
         | Kathula wrote:
         | What do you mean by "too intensely"? Is she having nightmares?
         | Does she often wake up, only to later fall asleep and having
         | nightmares again?
        
         | jbotz wrote:
         | She's probably putting the cart before the horse... light or
         | troubled sleep leads to more dreaming because REM sleep phase
         | comes just before a waking or almost waking phase. Also, you
         | most vividly remember those dreams that happen just as you are
         | waking up, so the more often you wake the more intense your
         | dreaming seems.
        
         | nerdponx wrote:
         | Consider that maybe the intense dreams are a reflection of
         | physical processes in the body that cause sleep to not be
         | restful. That is, both intense dreams and not feeling rested
         | are maybe caused by the same underlying thing.
        
         | FailMore wrote:
         | You/she might enjoy: https://psyarxiv.com/k6trz, discussed on
         | HN here: https://news.ycombinator.com/item?id=19143590 [written
         | by me]
        
       | drevil-v2 wrote:
       | Hmmm this is interesting. I wonder if people that cannot sleep
       | more than 4-5 hours per night also have very vivid dreams? And
       | therefore the brain cleaning REM cycle is just more intense and
       | prolonged so the mind-body decides it does not need to sleep any
       | longer?
        
         | axaxs wrote:
         | Data point, unsure if helpful. I sleep plenty but wake up at
         | least once per night. My most vivid dreams always occur in my
         | last sleep, usually after 6am. I can literally live a lifetime
         | in my dreams between 6 and 9am. I haven't quite figured it out
         | yet, but because my dreams are less than stellar, I usually
         | dread going back to bed.
        
           | brianjunyinchan wrote:
           | As another anecdote, on mornings when I can sleep in, I wake
           | up momentarily before my final doze (another 30m-1hr). That
           | wake always interrupts my most vivid dreams of the night
           | (whose events feel like several hours of real life, but
           | unsure about its real length).
           | 
           | Then, as I fall back asleep, I'm either wishing for/against
           | that dream topic to continue. Most of the time not getting
           | what I want.
        
           | JKCalhoun wrote:
           | I often feel these waves of ... something ... flush and
           | course through my head when I drift off and am still semi-
           | conscious. I know it happens when I begin to nap, I think too
           | it may happen early in the morning, just before waking. It
           | feels almost chemical.
        
             | drevil-v2 wrote:
             | I have had the same feeling too during a power nap. It
             | feels like a reboot to me. Perceptually when I wake up I
             | panic thinking it must have been hours then I look at the
             | watch and only 10 minutes have passed.
        
               | axaxs wrote:
               | Yes, that. I can wake up at 8, accidentally fall asleep,
               | and feel like hours or days have passed and panic, but
               | it's just 8:15. Dreams are so mysterious it's weird, in
               | our age of science.
        
             | joubert wrote:
             | Aren't those the ripples of theta waves that start to
             | emerge as alpha waves drop while you transition through
             | hypnagogia?
             | 
             | On the other end, as you transition out of sleep to
             | wakefulness, you pass through hypnopompia.
             | 
             | I experience the feeling of these waves also when I
             | meditate.
        
       | bjornsing wrote:
       | I don't buy it. Dreaming is computationally/metabolically
       | expensive. If the sole purpose was to prevent plasticity then
       | there would be far cheaper ways to accomplish the same result.
        
       | nmstoker wrote:
       | Is the suggestion meant to be that this only applies in certain
       | kinds of brain function areas (eg for continuous senses, ie
       | sight, sounds, etc) The reason I ask is that I don't need to
       | repeatedly dream of bicycling actions to be able to keep
       | bicycling - I might not use that skill for a long period and yet
       | I can still do it with accomplished ease when I resume it after a
       | gap. This suggests that the bicycling neural area (and likely
       | those for other similar skills, assuming there is indeed an
       | "area") does not suffer the kind of neural take over they
       | hypothesise.
        
       | User23 wrote:
       | I've always suspected dreaming plays a role in fixing short term
       | memories into long term ones.
        
         | ratww wrote:
         | Interesting. Recently my cat's vet (who's also a researcher)
         | told me that the best guess they have is that animals dream
         | about the things they did in the day so they can create long
         | term memories. Wonder if it's the same for humans.
        
       | baxtr wrote:
       | Hmmm somehow I'm a bit skeptical. The article itself includes an
       | example that is not easily reconcilable with their theory: What
       | about the people like the boy who became blind they mention in
       | the beginning? Shouldn't they have extreme visual dreams even at
       | day to protect their visual area, at least if this theory was
       | true? But instead the brain area was rewired.
        
         | arbol wrote:
         | It explained this with the example of the blindfolded braille
         | readers. Over 5 days their sense of touch was enhanced,
         | presumably at the expense of their visual senses. Over time,
         | the visual cortex would be completely taken over if the brain
         | was not receiving signal from the eyes.
        
           | kolinko wrote:
           | But if the theory were true, they would begin to see
           | hallucinations while awake as a way of protecting the brain
           | from changes.
        
             | subaquamille wrote:
             | And that's exactly what's described at the end of the
             | article:
             | 
             | > If dreams are visual hallucinations triggered by a lack
             | of visual input, we might expect to find similar visual
             | hallucinations in people who are slowly deprived of visual
             | input while awake. In fact, this is precisely what happens
             | in people with eye degeneration, patients confined to a
             | tank-respirator, and prisoners in solitary confinement. In
             | all of these cases, people see things that are not there.
        
               | baxtr wrote:
               | And that's exactly my point :) Shouldn't this have
               | happened to those blind people, too?
        
               | goodthenandnow wrote:
               | Good point. Also: is the visual information transmitted
               | by the optical nerves when you don't have eyes equal as
               | when the eyes "see" darkness?
        
       | scatters wrote:
       | The article says that "dreams are primarily visual". That might
       | be true for most people (and for the researchers), but I'm
       | aphantasic and I don't think I've ever had a visual dream. My
       | visual cortex seems to work perfectly fine on waking (though I do
       | find a sunrise alarm clock useful in winter). If this is typical
       | among aphantasics then I don't see how the theory can possibly be
       | correct.
        
         | brianpan wrote:
         | The theory could be correct in general (dreams are a result of
         | a evolutionary trait that keeps visual circuits active at
         | night) while not apply to you specifically, especially if you
         | are different than most people when it comes to
         | vision/visualizing.
        
           | kolinko wrote:
           | But the prediction of the their theory is that without visual
           | dreams his visual cortex would be overtaken by other senses.
           | 
           | Since this doesn't happen, it's an important datapoint
           | towards a falsehood of the theory.
        
       | kenjackson wrote:
       | I don't buy the theory. If you lose your vision, like the boy in
       | the story then I'd expect that you'd eventually stop dreaming. It
       | doesn't make sense that other senses would start then fighting
       | for protection of their neural circuitry. Why didn't they earlier
       | then?
       | 
       | What feels more likely to me is that your brain is trying to
       | optimize something in it, which is why it is correlated with
       | plasticity. The brain has evolved to turn off most of the body
       | (since there's probably strong selection against moving limbs
       | while sleeping), but little selection against moving eyes while
       | closed. REM is just what is left of our bodies movements.
        
       | dwighttk wrote:
       | Well. I don't (or very rarely) _remember_ my dreams. Hope I get
       | the protection anyway.
        
         | sci_prog wrote:
         | I used to dream a lot and then it all stopped, especially when
         | the pandemic started and I became less physically active. Long
         | story short, It turns out I have a severe sleep apnea and it
         | became more pronounced when my physical activity went down
         | significantly (aka I was less tired). Few days later after i
         | started using my CPAP machine my dreams came back. Make sure
         | you don't have sleep apnea, about 7-8% of people have it.
        
         | pixelbash wrote:
         | Anecdotally some b6/b12 supplements have given both me and my
         | partner very intense dreams and vivid recall. No idea what the
         | mechanism might be (Or if it's a preservative/etc) but
         | potentially an interesting data point?
        
           | kirykl wrote:
           | Particularly the P5P form of vitamin b6 will cause pretty
           | crazy and vivid dreams
        
           | dwighttk wrote:
           | I've heard Stilton cheese has a similar effect. (Haven't
           | tried)
           | 
           | Also whatever malaria drug I took was supposed to have
           | intense dreams as a side effect. (Don't remember any)
        
             | esperent wrote:
             | IIRC the cheese thing is basically a myth, any heavy food
             | in your stomach when you sleep will cause you to sleep less
             | deeply, wake more often, and consequently, remember more of
             | your dreams.
        
               | dwighttk wrote:
               | Makes sense... I usually only remember dreams when my
               | sleep is disturbed so this matches up.
        
             | rmilk wrote:
             | Funny that some medications have these dream effects. An
             | uncommon side effect of Montelukast is vivid nightmares and
             | sleep paralysis. It's a relativity common asthma control
             | medication, but was recently moved to a not-recommended
             | status for younger people because of this side effect. My
             | personal experience was pretty intense nightmares 1-2 times
             | a week if I took it before bed. Taking early in the day
             | stopped this side effect.
        
         | davrosthedalek wrote:
         | Try changing your room temperature by a degree or two. This
         | makes a big impact for me.
        
           | hndudette wrote:
           | Changing it up or down?
        
             | davrosthedalek wrote:
             | Try both.
        
         | neom wrote:
         | Out of curiosity, are you a frequent cannabis user? I found I
         | didn't remember my dreams when I smoked cannabis, however after
         | a long break I started to remember dreams vividly.
        
           | Taylor_OD wrote:
           | Yup. I smoked pretty heavily for two years and didnt really
           | dream at all during that time. Outside of those two years
           | I've always had pretty vivid dreams.
           | 
           | A dream journal really does help though. The last thing most
           | people want to do when sleepy is write though.
        
           | majkinetor wrote:
           | I can confirm dreamless nights on cannabis and vice-versa.
        
           | handmodel wrote:
           | Interesting - I pretty much never remember my dreams. I only
           | started smoking/edibles fairly recently in life and one side
           | effect was if I take an edible in the evening I almost always
           | remember them.
        
           | dwighttk wrote:
           | Nope.
           | 
           | The only time I seem to remember dreams is when my sleep is
           | disturbed. Most nights I go to sleep and wake up in the
           | morning, no (remembered)dream. If something wakes me up like
           | indigestion or needing to pee I'll often remember a dream.
        
             | tylorr wrote:
             | This is the exact same for me. Only a disturbance in my
             | sleep allows me to even remember that I had a dream at all.
        
           | keerthiko wrote:
           | I personally hardly ever use cannabis, and often oscillate
           | between periods of distinctly remembering all my dreams to
           | having weeks of seemingly dreamless sleep. The oscillations
           | have gotten especially wild in post-lockdown pandemic life.
        
           | [deleted]
        
         | tgv wrote:
         | Of course. Articles such as the "OP" are simplistic bollocks.
         | For starters, you'd be completely blind by now if the article
         | had any merit. And deaf. And lost all memory.
         | 
         | Oh no, wait: we open our eyes every morning, so even if there
         | was any effect, it would be the opposite: visual taking over
         | everything else. Which also doesn't happen.
         | 
         | So take it with a grain of salt: yet another unprovable
         | "theory" about the brain.
        
           | silverpepsi wrote:
           | Have you stopped to think for a second where science would be
           | if every possible hypothesis was thrown out as soon as its
           | inventor realized he couldn't conclusively prove it in a day?
           | 
           | Also exactly the fact that it hasn't been fully proved out
           | yet is why the nuance is missing. But now all the sudden you
           | want them to be able to give you an explanation of the
           | nuanced mechanism that prevents visual from taking over
           | everything else? (Plus why on earth would it? What are you
           | even talking about? I'm seeing all day long, but I'm also
           | smelling hearing touching and tasting) Make up your mind!
        
             | tgv wrote:
             | 1. If it's just a hypothesis, write it up in a journal,
             | don't put it in Time magazine.
             | 
             | 2. The hypothesis is as unprovable as they come: not only
             | do we not have any idea on how this process of taking over
             | other brain areas would work, if you knew how it worked,
             | you couldn't build brains that lack this mechanism but are
             | identical for the rest, and set up an experiment in which
             | half of the brains (modified and original) would dream and
             | the rest wouldn't. Because that seems to be about the only
             | experiment that could truly falsify this idea.
             | 
             | 3. It doesn't explain why only the visual cortex is
             | susceptible to this, when we know that other brain areas
             | also can adapt. The argument "it's dark" doesn't cut the
             | mustard, because the effect should go away as soon as we
             | open our eyes, which is around 2/3rds of the day. BTW,
             | babies can't see, so it's odd that so many of them manage
             | to develop a normally functioning visual cortex.
             | 
             | 4. Sleep inhibits the senses, so how can the areas they
             | input to take over, and why don't their areas get taken
             | over?
             | 
             | 5. They don't even attempt to prove that REM sleep and REM
             | sleep alone activates the visual cortex and only that.
             | 
             | > Make up your mind!
             | 
             | That was under the assumption that the hypothesis was true.
             | It seems to lead to rather unintuitive predictions. And I
             | do like a theory to not be in apparent contradiction with
             | simple observations.
             | 
             | So no, I have no reason to take it seriously, and people
             | that (think they) don't dream shouldn't worry.
        
               | dwighttk wrote:
               | Don't worry, I'm not worried.
               | 
               | I hear a lot about people struggling with sleep and so I
               | recognize that it is probably a widespread problem, but I
               | sleep like a rock most nights and have little to no
               | stress about it.
        
         | hutzlibu wrote:
         | Probably.
         | 
         | But if you want to remember your dreams again, this is
         | something you can work/train with. Basically, every morning
         | before getting up, not jump up with the alarm out of bed, but
         | rather ly still, in the same position as before and try to
         | remember. If you want to, have a dream diary. Doing so a few
         | days, should bring your memory of your dreams back.
         | 
         | I used to do so to train my ability for active/lucid dreaming.
         | Can be fun ...
         | 
         | (but now with a toddler and a baby I lack the time and focus)
        
           | brianjunyinchan wrote:
           | I often remember the dream right when I wake up, but if I
           | don't immediately focus on remembering it (e.g. while writing
           | it down), later in the day I almost magically won't remember
           | even what the general topic was.
        
           | dwighttk wrote:
           | I'd say about once a month I'm dreaming as I wake up and the
           | dream quickly fades... but if I had a dream journal there'd
           | be something to write down.
           | 
           | Every other morning there's nothing.
        
           | dtauzell wrote:
           | You can also write down your dreams if you wake after a dream
           | in the middle of the night. The downside is you might start
           | waking up frequently to write down your dreams.
        
       | syrrim wrote:
       | This doesn't explain why consistently interrupting REM sleep will
       | lead to death.
       | 
       | Also, the exposition suggests that this is somehow particularly
       | necessary for visual information because we can't see while
       | sleeping. They originally suggest that this is because it's dark
       | at night, but later modify it to be because one's eyes are closed
       | while sleeping. However, to my knowledge, very little hearing is
       | done while one is sleeping, certainly not enough to protect the
       | auditory portions of the brain from being taken over.
       | Furthermore, if other senses like hearing or smelling are in fact
       | unused while sleeping, it seems like there wouldn't be much need
       | to protect certain regions of the brain from takeover, since
       | there would be no other sense to take them over. Finally, it
       | seems like there are multiple situations where senses are
       | required in a periodic way, such as an animal active during dusk,
       | where its senses transition from being more to less sight
       | focused. Being able to cycle the role of brain regions in
       | response to these changes would be widely beneficial, and we
       | would expect the capacity for this to be deeply ingrained.
       | Insofar as we need non-sight senses while we are sleeping, it
       | seems like the circuitry to deal with cyclic use of senses would
       | be able to protect the visual cortex from total reuse.
       | 
       | Stronger than all this, it seems like REM is fairly fundamental
       | to sleep, in that understanding it ought to offer deep insight
       | into why we sleep in the first place. The proposed explanation
       | offers no such insight, and generally answers no other questions
       | besides the one regarding dreams. It seems like answers to deep
       | questions usually provide insight into questions we didn't even
       | know we had, whereas this answer provides no such insight.
       | 
       | I saw an answer to the dreams question to the effect that the
       | brain cools down while we are sleeping, and REM sleep heats up
       | the brain to prevent it from becoming too cold. This answer
       | potentially provides insight into why we sleep, in that it
       | proposes the cooling of the brain to be important to sleep,
       | rather than incidental. It also explains why interrupting REM
       | would kill a person. It doesn't obviously preference visual
       | portions of the brain, suggesting that visual information is the
       | focus of the brain simply because it is what the brain focuses on
       | while awake. It potentially explains the data of these
       | researchers, if the brain cools down more during sleep whenever
       | the brain is more flexible.
       | 
       | I am not suggesting that I think this answer is definitely true,
       | but merely trying to demonstrate that the standard I am measuring
       | this new theory against is not impossible to reach. I think the
       | explanation of why we dream will look more like the brain cooling
       | answer, rather than the brain reuse answer.
        
         | lawrenceyan wrote:
         | REM sleep is when your brain does maintenance and cleaning,
         | particularly with respect to the lymphatic/immune system.
        
           | daen1on wrote:
           | There's so much information about Sleep in Matthew Walker's
           | "Why we sleep". I strongly recommend it. <3
        
             | vosper wrote:
             | You may be interested to know that the book has come in for
             | strong criticism, including an accusation of deliberate
             | manipulation of data.
             | 
             | See: 'Matthew Walker's "Why We Sleep" Is Riddled with
             | Scientific and Factual Errors'
             | 
             | https://guzey.com/books/why-we-sleep/
        
               | melomal wrote:
               | Hmmmm...there's a whole article on that blog about 'why
               | you should have a blog' which to me reminds me of
               | 'flatting the curve' medium post which was written by a
               | 'marketing manager'....
        
               | vosper wrote:
               | Are you implying that the author of the post I linked to
               | is untrustworthy, because their site also has a post
               | about why it's good to have a blog? And then something
               | about Covid which has nothing at all to do with this?
               | 
               | Sorry, but this is just unfair insinuation, based on
               | nothing.
        
               | T-1000 wrote:
               | Walker's response to the criticism can be found here:
               | https://sleepdiplomat.wordpress.com/2019/12/19/why-we-
               | sleep-...
        
         | ben_w wrote:
         | > consistently interrupting REM sleep will lead to death.
         | 
         | I've seen this claim many times, but I've not seen any studies
         | that say "no [REM] sleep causes you to die". The closest I can
         | find are studies in the form "less [REM] sleep correlates with
         | _all causes_ of death to go up" - it's not like you can
         | literally kill someone just by keeping them awake for a month.
         | 
         | https://www.nhlbi.nih.gov/news/2020/study-links-poor-dream-s...
        
           | majkinetor wrote:
           | Indeed.
           | 
           | Without a good reference its just a repeated nonsense.
           | 
           | Even if this is true, there must be limits on it. What
           | qualifies as 'interruption' ? Does REM taking 10ms counts as
           | interrupted ? 100ms ? 1s ? 0ms (hard to believe this is
           | actually possible). Its also known that some people require
           | less sleep then others due to genetic factors. Perhaps 1m REM
           | is enough for some...
        
           | surgecoach wrote:
           | Do we take Star Trek as a authoritative source? lack of rem
           | sleep leading to violence, anarchy https://en.wikipedia.org/w
           | iki/Night_Terrors_(Star_Trek:_The_...
        
             | [deleted]
        
           | LinuxBender wrote:
           | I don't have a link handy, but I recall watching a
           | documentary where a bunch of college students participated in
           | a study that involved waking them every time they reached REM
           | state. After 6 days they started becoming psychotic. After 7
           | days someone stepped in and aborted the project as the
           | students were going fully psychotic. I don't recall who
           | intervened. They may not have died but if I recall correctly,
           | they would have killed each other.
        
         | raducu wrote:
         | There can be a lot of reasons we sleep.
         | 
         | Why do we have weekends?
        
           | gre wrote:
           | unions
        
       | irrational wrote:
       | To the best of my knowledge, I've never dreamed (I'm almost 50
       | years old). I've always wondered what that means about my brain.
       | Is there a medical or psychological label for people who don't
       | dream?
        
         | air7 wrote:
         | Healthy people dream several times a night and don't remember
         | most of their dreams upon waking.
         | 
         | Have someone monitor your sleep and wake you up when observing
         | REM. There's a good chance you'll remember the dream you're
         | currently in, and feel the disappointment of not knowing how it
         | ends...
        
         | tamrix wrote:
         | Everybody dreams unless you're brain dead during sleep. It's
         | more about if you can recall your dreams.
         | 
         | Some medications and /or weed can prevent dream recall.
        
         | easytiger wrote:
         | Presumably you do enter REM sleep though, in which case you
         | likely have no dream recall, which is not unheard of
        
         | noja wrote:
         | who don't dream, or don't remember their dreams?
        
         | matthewfcarlson wrote:
         | I dream fairly frequently but I'm very rarely myself or in a
         | place I've been before or with people I know. Dreams are weird
         | and I wouldn't worry about it too much.
        
       | chrisdbanks wrote:
       | Another prediction of this theory would be that naturally blind
       | animals such as some moles would not need REM sleep or would have
       | substantially less REM sleep. I couldn't find any research in
       | completely blind mammals, but in a mammal that has very poor
       | eyesight "Cape mole rats sleep substantially less than other
       | similarly sized terrestrial rodents but have a similar percentage
       | of total sleep time occupied by REM sleep."
       | https://www.researchgate.net/publication/301482322_Sleep_in_...
       | Seems like there is still a lot of scope for research on REM
       | sleep in non-human species.
        
         | pmontra wrote:
         | I think that this part of the article answers that
         | 
         | > those who are born blind (or who become blind early in life)
         | don't experience visual imagery in their dreams; instead, they
         | have other sensory experiences, such as feeling their way
         | around a rearranged living room or hearing strange dogs
         | barking. This is because other senses have taken over their
         | visual cortex.
         | 
         | The prediction would be that moles experience sounds in sleep,
         | or smell, or touch, whatever their primary sense is.
        
       | sundarurfriend wrote:
       | > dreams are primarily visual precisely because ...
       | 
       | This is a central claim in the article that's just stated and
       | taken for granted.
       | 
       | In my experience, at least, dreams are not _primarily_ visual.
       | They have a visual component, but also a vague auditory
       | component, a motor-experience (feeling of movement) component,
       | etc., and all of those feel equally important. And most of all,
       | there is a  "felt experience" component that actually feels like
       | the primary element of it; emotion is the core element of that,
       | but a better description is "the lizard brain's interpretation"
       | of what's happening in the dream, that feels like the central
       | element of the dream.
       | 
       | The visual part is also not in full colour generally, in my case,
       | it's like early movies during the transition from black-and-
       | white, with slight colour tints generally towards the bluish
       | colour regions.
       | 
       | I'm curious what others' dream experiences are like, and in
       | particular whether it's the case that most people do experience
       | them as primarily visual.
        
         | magicalhippo wrote:
         | For me, the dreams I remember seem indeed more like
         | _experiences_. I 'm often aware that I dream, and can sometimes
         | steer it. While it feels like a movie most of the time, it's
         | not really _visual_ in the same sense.
         | 
         | Like just yesterday I became aware that I was dreaming. In the
         | dream I had somehow ended up in jail. The majority of the dream
         | was me trying to escape in various ways, a bit like a reverse
         | Ocean 11 thing.
         | 
         | As I was dreaming I could picture the places around me, I
         | particularly recall the gate in the main corridor.
         | 
         | However even though my dreams are usually very visual in some
         | sense, it's much closer to how I picture things in my mind when
         | reading novels, rather than explicit images like when watching
         | a movie.
         | 
         | I've always had a hard time with visualizations when reading
         | novels. Like I'll read the page or two the author uses to
         | describe some location, but most of the time the details don't
         | really "sink in". Instead my mind seems to quickly grab hold of
         | the high-level things, like it's an old apartment building, and
         | the details are just generated based on that. Whatever detailed
         | description the author makes usually doesn't affect the mental
         | image I've already built.
         | 
         | I guess it's not that weird that the dream visuals feels more
         | like that out of a book, both cases being generated by the
         | imagination.
        
         | agumonkey wrote:
         | To me the most peculiar aspect of dreams is how vivid the
         | universe you're in is. It feels as emotionally impactful as the
         | best moments of your life. Super weird
        
           | alexpetralia wrote:
           | I've thought of dreams as unique in suspending self-doubt.
           | For some reason, while in a dream, we are incapable of
           | doubting what is going on. Everything feels incredibly vivid
           | and real. Then we wake up, and we go back to doubting: "Ah,
           | must've been a dream!"
           | 
           | Edit: Perhaps immersive psychedelics (LSD, ketamine) are
           | similar actually. Speculatively, one could define "real" as
           | our ability to doubt, "fantasy" as the suspension of doubt.
        
             | adamjb wrote:
             | Dreams made a whole lot more sense to me when I learnt
             | about idea of the brain as a predictive processing machine.
             | It asserts that the brain works as a sort of recursive two-
             | sided process, with theory creation on one side and
             | evidence collecting on the other. Recursive in that the
             | visual processing system might get a "is that a door?"
             | theory from a higher level system, which it'll then answer
             | by collecting and trying to match evidence from multiple
             | lower level systems ("is that an edge?" "is that a shadow?"
             | etc.) until it eventually reaches the level of processing
             | stimuli directly, with each system on the way acting as
             | both questioner and answerer.
             | 
             | In this framework dreaming is when the evidence collecting
             | side becomes a lot less rigorous than it usually is, so it
             | says "sure, why not" without reference to a stimulus (i.e.
             | a way to be falsified). In other words it's the brain's
             | predictions continuously coming true.
        
               | sundarurfriend wrote:
               | > brain as a predictive processing machine. It asserts
               | that the brain works as a sort of recursive two-sided
               | process, with theory creation on one side and evidence
               | collecting on the other.
               | 
               | SlateStarCodex has a nice article[1] about this.
               | 
               | > The key insight: the brain is a multi-layer prediction
               | machine. All neural processing consists of two streams: a
               | bottom-up stream of sense data, and a top-down stream of
               | predictions. These streams interface at each level of
               | processing, comparing themselves to each other and
               | adjusting themselves as necessary.
               | 
               | > ...
               | 
               | > You're not seeing the world as it is, exactly. You're
               | seeing your predictions about the world, cashed out as
               | expected sensations, then shaped/constrained by the
               | actual sense data.
               | 
               | [1] https://slatestarcodex.com/2017/09/05/book-review-
               | surfing-un...
        
             | rtx wrote:
             | One theory I had read a longtime ago was that nightmares
             | were a way for the subconscious mind to wake-up the
             | conscious mind.
        
           | krapp wrote:
           | The same brain that simulates your entire perception of
           | reality from external inputs is using all of its resources to
           | simulate its own, with itself as an input.
           | 
           | What's really weird is how dream-reality always makes _sense
           | to you_ in context, regardless of how absurd or random it is,
           | because your self awareness and identity are being simulated
           | the same way, both in dreams and in reality. It 's like a
           | virtual machine inside a virtual machine.
        
           | lisper wrote:
           | I occasionally have lucid dreams, where I realize I'm
           | dreaming. When that happens, I can take control of the dream
           | and do cool things like fly. Usually this only lasts a minute
           | or two and then I wake up. But on a handful of occasions I've
           | reverted to a non-lucid state, where I _forget_ that I just
           | figured out that I 'm in a dream, and I lose control again.
           | It's super freaky, and raises some pretty deep existential
           | questions: who/what exactly am I when I'm in that state? How
           | can I ever really be sure that I'm _not_ dreaming?
        
             | GordonS wrote:
             | > I occasionally have lucid dreams, where I realize I'm
             | dreaming. When that happens, I can take control of the
             | dream and do cool things
             | 
             | I experience lucid dreams I can control quite frequently.
             | The thing I do most often is let the dream play out, but
             | _go back in (dream) time_ to replay certain scenes
             | differently if I 'm not happy with the outcome.
             | 
             | It's really pretty cool - like being in some kind of super-
             | advanced VR simulation, or under the influence of some
             | impossible drug. If anyone ever figures out tech to make
             | this just happen (kind of like simulation VR goggles in
             | scifi films), they are going to be very, very rich.
        
             | bonoboTP wrote:
             | In another kind of "weakly lucid" dream type I know I'm
             | dreaming but I don't have (full) control. So I can't make
             | people answer what I want, but it feels like I can
             | "mentally manipulate" them and push their answer to a
             | certain direction, like make an attacker friendlier or so.
        
         | hx2a wrote:
         | I've had recurring dreams that were entirely in math. And by
         | that I don't mean a dream where I was sitting in math class or
         | something. I mean the actual substance of the dreams were
         | equations that I was trying to make sense of.
         | 
         | In my awake life I like math a lot and am comfortable solving
         | equations. The dreams themselves, though, were terrifying in
         | ways no other dream has ever matched.
        
         | mailslot wrote:
         | I'm able to consciously enter dreams from waking state.
         | Basically, lucid dreaming on hard mode. Like going through
         | sleep paralysis on purpose.
         | 
         | Dreams are so close to waking state, I'm always in awe when I
         | successfully transition. Touch, taste, smell, every sense. It's
         | like waking reality, but with god mode.
         | 
         | That said, vision is really really weird. If you pull your
         | sight into your dream body (hard to explain), then it's just
         | like you'd expect. It's like it's possible to see multiple
         | perspectives at once, and it's visual, but it's all like one
         | continuous field of view. Sometimes I don't even really notice
         | that I'm looking forward, backward, and from above all at once.
         | 
         | When I'm just playing around, I like to smash things and jump
         | so high that I fly above the clouds, feeling the cold air above
         | and the weightlessness at the apex. It's no more visual primary
         | than waking, IMHO.
        
           | ford_o wrote:
           | How do you pull it off?
        
         | [deleted]
        
         | dqv wrote:
         | I experience the same color dullness, although warm colors like
         | red are more vivid for me.
         | 
         | Something I've noticed that I've never heard anyone else talk
         | about is _text-based dreams_. That is, the dream primarily
         | happens in a text interaction where the visual space is
         | completely engulfed by a chatroom-like interface. The visual
         | element is not the primary aspect of the dream, instead the
         | text in the dream is projected into the visual space. Obviously
         | this is because I spend a lot of time in chatrooms.
        
           | opan wrote:
           | I've had many dreams featuring IRC or the chat of an old MMO.
           | I also heard it's very uncommon to see text in dreams,
           | though.
        
       | joveian wrote:
       | The evidence doesn't support as close a relationship between
       | dreaming and REM sleep as the authors suggest. See:
       | 
       | Solms. 2000. Dreaming and REM sleep are controlled by different
       | brain mechanisms. BEHAVIORAL AND BRAIN SCIENCES (2000) 23,
       | 793-1121.
       | 
       | https://neuro.bstu.by/ai/To-dom/My_research/Papers-2.1-done/...
       | 
       | >>It is generally accepted that NREM mentation that is
       | indistiguishable from REM dreaming does indeed occur. Monroe et
       | al.'s (1965) widely cited study suggests that approximately
       | 10-30% of NREM dreams are indistinguishable from REM dreams
       | (Recht-schaffen 1973). Even Hobson accepts that 5-10% of NREM
       | dream reports are "indistinguishable by any criterion from those
       | obtained from post-REM awakenings" (Hobson 1988b, p. 143). If we
       | adjust this conservative fig- ure to account for the fact that
       | NREM sleep occupies ap- proximately 75% of total sleep time, this
       | implies that roughly one quarter of all REM-like dreams occur
       | outside of REM sleep.<<
       | 
       | A recent reference that discusses this is:
       | 
       | Nicholas and Ruby. 2020. Dreams, Sleep, and Psychotropic Drugs.
       | Front Neurol. 2020; 11: 507495.
       | 
       | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7674595/
       | 
       | >>Regarding the link between dreaming and neurophysiology, 60
       | years of debates has been necessary to get rid of the rapid eye
       | movement (REM) sleep hypothesis of dreaming, and it is now
       | acknowledged by a majority of dream researchers, be they
       | neuroscientist or not, that REM sleep is neither necessary nor
       | sufficient to get a dream report and that dream reports can be
       | obtained at the awakening of any sleep stage (2, 7, 9-12). It is
       | also now clear that the complexity and story-like characteristics
       | of dream reports are related to sleep stages but also, and even
       | more so, to circadian rhythms leading to more vivid and complex
       | dreams in the morning than in the early night [e.g., (13-15)].<<
        
       | dariosalvi78 wrote:
       | I see a lot of correlation here and very little causation, what
       | if the visual dreaming is an effect of some other, more
       | fundamental, mechanism?
        
         | vbezhenar wrote:
         | My pet theory is that brain uses its power at night to process
         | data from different organs and to fine-tune their settings
         | (especially guts which is extremely complex organ with millions
         | of sensors). That's why sleep deprived creature dies from
         | misbehaving organs. Some neurons are not required for this
         | task, because they are too specialized. Namely neurons
         | responsible for vision, conscience, movement. They receive
         | random signals which don't really mean anything and more like
         | white noise. But brain is brain, so those neurons are trying to
         | make sense from that noise and that's how dreams are created.
        
       | seesawtron wrote:
       | Link to original paper which is still a non-peer reviewed biorxiv
       | article [0]. The crux of the paper is based on expressions of
       | plasticity correlating with the percentage of sleep time spent in
       | REM (fig.2). Apart from the high-level questions raised already
       | in the comments there are several caveats in the data:
       | Data points are sparse i.e. the number of samples included are
       | too few to strongly believe in correlations. Taking out extreme
       | data points would make the correlations look independent.
       | The data values across 25 primate species are based on averages
       | across previous studies and using proxies where some data was not
       | available. I do not know how justifiable such approaches are but
       | I am skeptical about them.
       | 
       | [0]
       | https://www.biorxiv.org/content/10.1101/2020.07.24.219089v1....
        
       | GordonS wrote:
       | I really love when I have strange dreams, especially when you go
       | back into the same dream if you wafe briefly, giving you a moment
       | to consider before it continues. I imagine it's unlikely there is
       | any real meaning behind dreams, but I can't help but feel there
       | must be sometimes, especially with some of the odder dreams.
       | 
       | The most disappointing thing about a good dream though, is how
       | _quickly_ memories of it fade away upon wakening - it 's like
       | trying to grab tendrils of smoke rising away.
       | 
       | Usually at best I manage to recall one or two small snippets, or
       | something about the general theme, but every now and then - very
       | rarely - more vivid details stick with me for a little longer.
        
       | yalcinbar wrote:
       | I have always woken up feeling rejuvenated if I could remember
       | what I had dreamt vividly. I asked some of my friends if it's the
       | same with them also, but they said it's the opposite.
        
       | [deleted]
        
       | EugeneOZ wrote:
       | So by their theory blind people don't need to sleep? Total
       | bullshit.
        
         | silverpepsi wrote:
         | Well, why are you implicitly insisting on the unproven theory
         | that "sleep serves just one single purpose" - one that no one
         | else has proposed? What if sleep is needed for more than one
         | reason? Is the complexity of the world so hard to fathom that
         | you throw up your hands and yell 'bullshit' on the first hint
         | of challenge!
        
           | EugeneOZ wrote:
           | Lol. Please quote where I'm saying this. I never wrote that
           | phrase you quoted in your comment. Are you trying to lie? :)
           | 
           | Better read my words one more time:
           | 
           | "People see dreams not every time they sleep, not every
           | night, sometimes we can have multiple nights without dreams.
           | By this moronic theory our "visual cortex" should be modified
           | to "blind mode" just in the first night of sleep without
           | dreams."
        
         | nhumrich wrote:
         | dont need to _dream_. The article is about why we dream, not
         | why we sleep.
        
           | EugeneOZ wrote:
           | and? Still total bullshit.
        
             | sa1 wrote:
             | Their theory says nothing about sleep, except that your
             | visual cortex isn't receiving any input.
             | 
             | You're making a mistake in conflating dreams and sleep.
        
               | EugeneOZ wrote:
               | You and they making a mistake saying that blind people
               | should not see dreams. I wonder how such an idiotic idea
               | reached the HN at all. It's Daily Mail level.
               | 
               | People see dreams not every time they sleep, not every
               | night, sometimes we can have multiple nights without
               | dreams. By this moronic theory our "visual cortex" should
               | be modified to "blind mode" just in the first night of
               | sleep without dreams.
               | 
               | Articles containing words "Mother Nature" are only good
               | for religious organizations, homeopathy lovers and other
               | imbeciles.
        
               | silverpepsi wrote:
               | I would recommend rereading the article, your reading
               | comprehension wasn't up to par to tackle it in one pass.
               | Also you're assuming a TON of things that were never
               | suggested. Jumping to conclusions won't help you read
               | what was written I'd say
        
               | EugeneOZ wrote:
               | Quote where I'm wrong or don't start it. Just saying "a
               | TON of things" without a single example is ridiculous.
        
         | bencollier49 wrote:
         | No, whatever their visual cortexed had been repurposed to do
         | would be preserved. They might dream in "clicks". But I'm
         | inclined to disregard this theory, it's overly simplistic, and
         | doesn't explain vast reaches of sleep phenomena.
        
       | yogrish wrote:
       | In this article, there is a mention of "constant battle going on
       | inside our brains between different sets of neurons, fighting
       | over who gets control of certain parts of the brain." Because of
       | which visual cortex always gets activated (even in sleep)so that
       | it's neurons are not repurposed for other activities. Hence we
       | dream. http://m.nautil.us/issue/91/the-amazing-brain/your-brain-
       | mak...
        
         | majkinetor wrote:
         | This!
         | 
         | Predatory neuron phenomena goes along with this theory.
        
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