Hi, I'm Associate Professor Bruno van Swinderen. Why and how do we sleep and what is consciousness? Are all animals that sleep by definition conscious when they are awake? I study fruit flies and have recently published research which shows that flies have distinct sleep stages. General anaesthetics abolish consciousness in humans, but how do they really work? My research shows that common mechanisms might be involved in all animals. What do sleep and general anaesthesia together tell us about how the brain works?

Proof: https://twitter.com/QldBrainInst/status/958829752034512896

EDIT: Thanks for all of the discussion everyone! I'll be tuning out now and leaving this stimulating discussion to the rest of you. I appreciate your questions and hope some of my answers made sense. We'll see how the research goes.

EDIT: If you're interested in learning more, I explain more on this episode of A Grey Matter podcast, out today.

Comments: 1301 • Responses: 37  • Date: 

donfelicedon2887 karma

This might be a stupid question, but are there any biological similarities between daydreaming and dreaming at night? Like, are the same connections happening in our brains or whatever?

QldBrainInst1357 karma

That is actually an excellent question and I do believe serious research is being done on that. It would be great if we could accomplish some sleep functions while we are awake. Maybe that is what happens during meditation, and many people say that meditation is important for their well-being, making them feel refreshed. It could thus be accomplishing deep sleep functions. On the other hand, daydreaming could be accomplishing some REM sleep functions, which might involve emotional learning. Not sure about the neural correlates though, both are essentially wake-like states. One could look if certain brain structures, such as the pons, are behaving in a similar way.

One aspect of your question is actually of great interest to me: are sleep and wake really all that different, in terms of brain functions and processes? We think they are very different because when we wake up we have a conscious experience of changing states. But maybe the brain was doing something very similar all along: blocking out the world, just a little bit more during sleep. Maybe we have been blinded by our fixation on our own consciousness, which is not the end-all of what a brain does.

anow2583 karma

But maybe the brain was doing something very similar all along: blocking out the world, just a little bit more during sleep. Maybe we have been blinded by our fixation on our own consciousness, which is not the end-all of what a brain does.

mind blown.

Beemow68 karma

So the waking world is just a carrot dangling on a string in front of us? We become fixated on it, and lose sight of all the other weird mumbo jumbo going on?

Methuen33 karma

Or perhaps the opposite - we spend most of our life more or less asleep, not paying attention to what's around us.

QldBrainInst114 karma

It could be argued that the brain's ground state is to block out the world, and that perception is when solutions are found that link sensory stimuli to actions. In that way, yes, it is possible that we spend most of our life only looking out of a narrow, moving peephole, and that during sleep that peephole get's blocked. We think that the peephole is a big deal, because it gives us consciousness, and ignore the processing that is happening most of the time during wake as well as sleep.

QldBrainInst37 karma

I'm interested that this was the most popular question/reply. Just to elaborate: when we pay attention to the world, we are also blocking most everything out, except for a small moving window, a window that is greatly influenced by our history. When we sleep, that window closes (deep sleep), or moves around in a strange internal world. But in both cases, the brain is doing what it does best: block out the overload of stimuli around us. Why should the mechanism (of blocking) be different, especially in animals like flies (which sleep and also pay attention)? We feel like these states have to be very different, but that may be a delusion. Maybe the ground state for the brain is to block information, whether that brain is a fly's or a human's. Thanks for helping bring these ideas to the top of this interesting discussion session.

donfelicedon210 karma

Thanks for the reply!

QldBrainInst42 karma

Here is some work being done at The University of Queensland, related to this:


Golokopitenko447 karma

When I'm about to fall asleep, I think about the fact that I'm falling asleep, which takes me a few steps "back" into a more conscious state. This usually ends with me fully waking up and being unable to sleep.

Why does this happen?

QldBrainInst780 karma

Paying attention kills sleep. It's like the analogy of a butterfly landing on your arm. If you pay attention to it, it flies away. If you can just be aware of it without paying attention, it lands and you fall asleep.

heebythejeeby357 karma

Aside from quitting my job, what can I do to best mitigate damage done by shift work related sleep disruption?

QldBrainInst608 karma

Not worry about it. You will get the sleep you need. Most of insomnia is sleep anxiety, worrying that you are not getting enough sleep. Sleep is a homestatically regulated, it adjusts itself in most of the time because it is such a powerful drive.

scythentic316 karma

How come some animals sleep for much longer than others? For example a lion sleeps for around 20 hours a day but a cheetah sleeps for 12 hours.

QldBrainInst519 karma

This is a big mystery. Even worse, ungulates (cows and antelopes and such) only sleep for a couple (3-4?) hours. At the other end, some bats sleep about 18 hours. Flies sleep about 8-10. Clearly this has nothing to do with intelligence or brain size. It all relates to the multiple functions of sleep, and how these can be accommodated into an animal's specific niche. We can talk about those hypothesized functions.

IAlreadyAmRight198 karma

Why do we sometimes not remember our dreams?

QldBrainInst436 karma

We don't remember most of our dreams! For example, the ones at the beginning of the night after your first deep sleep cycle, that you just slept through. I bet those were pretty interesting, but they are lost forever. One important thing to keep in mind about dreaming is that it probably has less to do with the narrative content you remember than the neural activity that is happening at the time, which is probably maintaining some crucial function in the brain, like emotional balance.

AlzScience176 karma

Hi Dr. van Swinderen, I'm a neuroscience student studying Drosophila as well. I've read a few of your papers previously and found your work extremely interesting! My field is Alzheimer's research, so I'm curious what you think about the connection between sleep and Abeta clearance. Do you think the primary function of sleep is to clear away Abeta and other toxins from the brain? Or is it serving other roles in memory consolidation that are independent of toxin clearance?

QldBrainInst134 karma

Nice to hear from another fly person. Metabolite clearance is probably just one of many sleep functions, and ancient cellular process that has found a convenient home when the brain is offline for other sleep-related purposes, such as synaptic homeostasis, memory consolidation, etc. I've outlined some of these proposed functions above; it's not all about Abeta.

InfinitesimalBlip169 karma

Could our waking conscious experience be an extension of primitive REM sleep? Imagine primitive species with really basic neural circuitry that respond to a stimuli, then re-engage that circuity during a restful state to consolidate that response and make it more efficient next time. It would be advantageous in this case to engage that circuity without actually performing the action, in a similar way to REM. Maybe simulating the environment was such an advantage that animals spending more time in a 'simulated' state were selected. Fast forward millions of years... we spend the majority of our time in this simulated 'REM-like' state?

QldBrainInst132 karma

This is a very interesting idea, and I have some thoughts along these lines. Can I get back to you in a bit about this? Duty calls for my day job.

InfinitesimalBlip69 karma

yeah of course. Thanks for your time.

QldBrainInst218 karma

I love your idea here. I think that key to it is what we mean by efficient. What I think we mean is that we learn better while awake, so we don't make maladaptive mistakes. I think this is where REM sleep plays an important role with regard to emotional responses. When something unpredictable happens in reality, it is surprising and this is often associated with a prediction error signal and an emotional response. The emotion ensures that a new memory is formed to make better predictions. The waking brain basically wants to become a prediction machine. The price to pay for this (there is always a price) is that the waking brain will become less and less surprised in the context where it exists. This erodes the very system that allowed that learning to happen. My idea is that this is where the 'alternate realities' of REM sleep step in, to curate the brain's valence (emotional) system, to ensure that the waking brain will always respond with surprise, so it can keep on learning effectively. I like to think about this in the following way: consciousness is adaptive, and dreaming keeps us conscious. If we didn't dream, we would become maladaptive zombies. Actually, we do.

PotatowitheyesxD143 karma

Do fish sleep?

QldBrainInst291 karma

Yes. All animals with a brain sleep, as far as this has been carefully examined. I think there may be a male bullfrog out there that doesn't sleep, but it's probably in a pretty ragged condition.

The_Eleventh_Hour39 karma

I've heard that hagfish were purported not to sleep, or not to rely on it like other fish. I'm going to go check now, but curious if you have heard about them, or know anything regarding them and their sleep habits.

QldBrainInst127 karma

Don't know. If they don't sleep, there will be a price to pay at some point. Some animals get all their mating done without sleeping much. The price to pay is an early death. This has not been a good evolutionary strategy in general.

mooza7498 karma

Has my dog given me a name, and when someone is outside and he is barking he is actually barking out my name to come look?

QldBrainInst150 karma

Don't know much about barking dogs, except that they don't do it in the wild. I wish they were all wild.

DogLoverBoy9992 karma

Hi, I didn't actually know that many animals slept like us that's so cool! I did some reading and it's obvious that worms sleep like we do too, why do worms need to sleep? Do flies sleep like worms?

QldBrainInst129 karma

By worms, you probably mean nematodes (C. elegans), which is where the sleep research was done. I don't think worms sleep in the same way flies and humans do. I think that some aspects of their development have similarities with some (deep) sleep functions, but I don't think they have a 'sleep switch', meaning the capacity to rapidly and reversibly turn off responsiveness to the outside environment. By the same token, I don't think worms have a selective attention. Carrying this further, I think consciousness emerged from animals that have attention. This co-evolved with a need to sleep, to curate those attention mechanisms. This is just a hypothesis (which we have written about), but worth debating I think. Basically, nematodes aren't conscious. Flies are.

willbo201369 karma

Which animal dreams the most?

QldBrainInst172 karma

The natural history of dreaming is a fascinating question. Recent work shows that even reptiles dream. I'm not sure which animal dreams the most, but I've heard that echidnas and marsupials in general have a lot of REM sleep. Within humans, it is known that infants (even already in the womb) dream a lot more than adults. It all begs the question what dreaming is for, if it's in most animals and exists even before humans have narrative experiences they can talk about.

Tatters66 karma

For infant animals (such as humans) prior to birth, I wonder if what is showing up as dreaming is actually when DNA is writing instincts. Sort of an initial formatting of brain data with basic skills. Such as self-preservation, communication, emotions, and so forth.

QldBrainInst135 karma

WRT emotions, think of what emotions do for you. They are a way to attach value to prediction errors, when something doesn't go according to some internal model. That allows the brain to make new memories and prevent that error in the future. The first source of all prediction errors and internal models isn't the visual world or human interactions, it's all about motor learning in the womb. Where does my body begin and end? What is a consequence of my actions (sucking my thumb) or another's actions (mother rolling over)? I think this may be why infants 'dream' more, they are making those models of the world and assigning value to them. I think this is sort of what you are getting at as well, with 'instincts'.

gemi11236 karma

When my son was less than 3 months old he was dreaming and bust out in pure joyous laughter at such a young tender age. I’ve raised three kids and never heard something so pure and raw come from a young infant. How would it be possible for an infant to dream and laugh??? What could be funny to them at that age or was it more instinctual?

QldBrainInst111 karma

See my answer about prediction errors above. Laughing is the quintessential prediction error, funny jokes always have an expected twist, and it is a way for us to communicate that we have been surprised in a good, non-harmful way. Your child had a dream that evoked that, and he communicated that to you in his sleep. They do it all the time while awake; the easiest way of making my kids laugh was doing something harmlessly unpredictable, like putting a teapot on my head.

julesalexandra68 karma

Do you get enough sleep?

QldBrainInst208 karma

30% of people in modern societies suffer from insomnia. Personally, I don't think I get enough sleep. Kookaburras start braying at 4:30am here in Australia, in summer. I try to go to sleep earlier to accommodate, but who wants to go to sleep ay 9pm?

TuckRaker52 karma

Can you explain what happens to the brain through the process of sleep deprivation? Would everyone eventually go crazy if they were not allowed to sleep? Would they die at some point or just pass out?

QldBrainInst92 karma

Rats have been shown to die of sleep deprivation before they die of starvation. Not exactly sure what they die of, and that says a lot about our not understanding the various functions of sleep yet. Cognition suffers first, but then cellular and stress pathways go off. This probably relates to both REM and deep sleep functions; you can't do away with them. You'd die.

TuckRaker25 karma

Interesting. So, how long, on average, for an adult human to die of sleep deprivation. Thank you!

QldBrainInst49 karma

Total sleep deprivation, without microsleeps? The number I've heard is about 15-20 days, but don't hold me to it...

MyWindowIsBroken49 karma

what do dreams 'look like' to other animals? Does my dog dream about chasing balls? Do they have weird trippy dreams like we do?

QldBrainInst67 karma

The brain looks a lot like it's awake during REM sleep, even in other animals such as dogs and birds. I think the focus on dreams might be a bit distracting, it's just a human-centric, subjective angle that we've latched on to, just one sliver of what comes out of that sleep stage that is probably doing a lot of good things for the brain. That said, there is the possibility that we may be able to 'decode' REM sleep content in animals, because this has been shown to be possible in some human imaging. Verbal report always helps though, so we'd have to have imaging during behavioural experiments to know that these are being recapitulated in some way during animal dreams.

eythian32 karma

When I was studying AI, in particular neural networks, pseudorhersal was an idea as to what sleep could be doing (in part) to consolidate memory. What's the current belief or science regarding this?

(Pseudorhersal being the input of random input to a neural network, saving the result, and using these pairs to help integrate new information into the network, minimising loss of existing information.)

QldBrainInst29 karma

Sounds interesting, and sounds like you might be onto a function for dream sleep.

Lance_E_T_Compte30 karma

Sleep must be incredibly valuable to an animal. Given that most (all?) animals do it, and this requires a significant amount of time when they could be otherwise competing for food, mates, (or researching sleep), etc. The cost is immense!

What's your opinion of the benefit?

QldBrainInst58 karma

Sleep has multiple functions, this has been one of the confusing things about sleep: one word for several different functions, that have all been packaged into a time when the brain is 'offline'. These functions probably include: synaptic homeostasis (keeping synaptic strength within an optimal range - this is important, there are a trillion of them in your brain), waste clearance, memory consolidation, stress regulation, emotional and motor learning...

sexy_echidna22 karma

Can a dog have an existential crisis? Is suicide a thing in the animal kingdom? Do you think dolphins are able to develop a real romantic relationship with a human being? OMG. So many questions. All really regarding the consciousness subject.

QldBrainInst44 karma

There are some dolphins here near Brisbane (Moreton Island) who come to meet with humans every evening, to get free food. Sometimes, they've brought the humans gifts, like choice pieces of fish, and left them on the beach for them. Humans have collected those gifts in a big jar, you can see them at Tangalooma.

mouseff18 karma

How does what we expect to perceive change how we direct attention? Would you rate attention more bottom-up or top-down, is it more influenced by ones interna model of the world or the sensory input the brain receives? (I hope this is not A recurring questions :))

QldBrainInst19 karma

Great question. It probably evolves through life, starting with mostly sensory input and moving towards models as we gain experience. Some models are already there from the start. Is it a coincidence that REM sleep ontogeny shows this trend as well, changing through life? Maybe this is a clue as to what REM sleep does: curating our models of the world, and how we respond to prediction errors.

PolyAnthroBabe16 karma

Okay, so you study this in animals (rather than humans) but I'm curious what you'd recommend for humans who suffered alternating sleep deprivation and too much sleep during their formative years (8-25)? Overwhelmingly this public suffers insomnia and often other sleep disturbances (nightmares). Co-morbidity with trauma (they're ex-cult members).

So far I have the following:

  • Drop temp 2-3F*
  • Darken space
  • Regular schedule
  • Things that dampen sympathetic system (meditation)(music?)
  • CBT-I
  • Pink Noise & Music designed for sleep
  • Bilateral Stimulation (Bls) / EMDR
  • Exercise (but not too close to bed)
  • Eliminate blue light an hour or two before bed
  • No caffeine after 3 pm

Is there anything that can repair or compensate for the damage?

Thank you in advance :)

QldBrainInst16 karma

There is research being done in exposing to 1Hz modulated sound or even visuals, which has been shown to help clear metabolites (one of the purported sleep functions) in rats, I think (a talk from an MIT lab I heard recently, can't recall the name though). There is now a proliferation of visuals and sounds you can get online, and most of it is probably bogus. But more research needs to be done here: can we achieve key sleep functions while awake, and in this way try to supplement what is happening during sleep? This should be testable in animal models.

fringeHomonid9 karma

What is somethiing striking (similarity and/or difference) in the travel times of PNS stimuli signals and brain region activations in primates vs non-primates? IOW, do touch/pain signals travel faster or slower? Do other animal's PNS behave like ours, in that, does a pain signal reach the spinal cord and then a "flinch/withdraw" signal get sent to the motor neurons in order to decrease exposure to the source of the pain stimulus?

Are there animals with a disproportionate balance of myelinated vs unmyelinated nerves?

Is there anything that you did not at all anticipate or anticipate but did not show up?

Has your work influenced or been influenced by works of philosopher and cognitive scientists like Dr. Dennett from Tufts University? (I know he doesn't much care to be known by the latter title)

QldBrainInst14 karma

I'm not sure about the PNS. Dennet's book, Consciousness Explained, hasn't explained much as far as I can tell. Maybe worrying a bit too much about the human experience, not enough about how this phenomenon might have come out of evolution, as an adaptive feature of the brain.

we_can_eat_cereal9 karma

Do drosophila show similar spontaneous sleep patterns during their instar stages? Or is it only in the adult fly?

QldBrainInst11 karma

It isn't known whether larval flies sleep, although key sleep-like functions probably happen during metamorphosis, as has been shown in the nematode C. elegans. These relate more to development, and deep sleep is like a mini-development in a way, with physical changes happening at synapses. Personally, I don't think fly larvae show spontaneous sleep patterns, I think that like nematodes their sleep-like functions are all linked to programmed developmental changes.

should-have8 karma

What's the characteristic that separate us (consciously) from animals? What is it that we have, or can do, that they can't? I'm thinking more on a practical level than a biological. For instance, a lot of animals can communicate but we seem to be the only animal that can tell stories. What's the 'opposable thumb' of consciousness that we have?

QldBrainInst41 karma

I'd say the characteristic that separates you from animals is the same one that separates you from other humans: you have a different history. Your human history is one that taught you a language so you can tell us about your consciousness. Your personal history is a unique one only accessible to you, which no-one else in the world has. This is what makes you the conscious entity you are today, which is different than me and different than a dog or a fly. But why should the underlying mechanisms (e.g., selective attention and memory) be any different? You just have more to play with than a fly.

coryrenton8 karma

sleep deprivation studies in animals seem to result in death but is there any way to factor out the excessive use of stimulants involved?

QldBrainInst11 karma

Yes, you stimulate them twice as much, but let them sleep in between. This controls for stress, a regular protocol in our lab.

CsticPandora3 karma

Do animals experience REM?

QldBrainInst5 karma

Yes, definitely. See above.

lotusblossom60-1 karma

I had surgery once and before the anesthesia kicked in I felt pain. But not where they were cutting, in my head. Why?

QldBrainInst3 karma

Sorry, I don't have an answer for this. Happy to talk about mechanisms of general anaesthesia though.

Brighton1000-1 karma

What do you think about dream symbol analysis?

QldBrainInst1 karma

I don't know what this is, sorry.