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The Purpose of Sleep? To Forget, Scientists Say
- misotaur 10y ago"Life without absorbing occupation is hell; joy consists in forgetting life."
- sudoscript 10y agoThe brain naturally employs dimensionality reduction for memory. Sleep is one example. Another, simpler one is reading -- how far back can you remember word for word when you are reading something? Maybe a sentence at most? But you still remember enough to understand what you're reading, because of efficient dimensionality reduction. Some neural networks mimic this, such as LSTMs. But it's a poor mimicry at best. The brain has a natural, built-in selection mechanism. It seems to "know" what to remember and what to forget. How could we implement something like this in a deep neural network? (This is key step to giving computers "personality". Which emerges from a selective set of memories and trained behavior)
- gallerdude 10y agoA second neural net which decides which memories are important and which ones are not.
- stult 10y agoIt's homunculi all the way down...
- AnimalMuppet 10y agoI don't know how we implement it. But I've wondered for a while if we can't make a real AI until we create something that can sleep.
- grromrell 10y agoThe process in the article is pretty similar to dropout in neural nets. But instead of "knowing" what to get rid of, we randomly prune. The brain may do it randomly or intelligently, hard to say based on these studies. See here for info on dropout: http://bit.ly/1mneaL5 http://bit.ly/1mneaL5
- ianai 10y agoSeems like it scores the pruning algorithm and adjusts it as well.
- deathhand 10y agoAnyone who is curious about what sudoscript is talking about they should watch the HBO series "West World". The series dives directly into this question.
- state_less 10y agoHow should we account for humans with photographic memory?
- agumonkey 10y agoWhat scientific domains researched this ? I've been thinking about it for a decade at the shower thought level, but I'm eager to know more about this.
- Eerie 10y agoNo, no, that's the purpose of Drink.
- RcouF1uZ4gsC 10y agoAs an aside, in trying to make a title compelling (have a person as the subject), the Times is inadvertently hurting science. This article is about a hypothesis that has some evidence in mice, but tells nowhere near the whole story, especially in humans with regard to sleep. However, the title suggests more confidence than warranted. Likely, in the near future, some newspaper will publish a similar article, except the purpose of sleep will be to remember (which is also supported by studies). The problem is the average person will see that and think, what scientists say is always changing, and they are contradicting each other all the time. Then when they see an article stating scientists say that climate change is worsening, they will view it just like any article that has "scientists say" in the title.
- phasnox 10y agoYou should know, nobody takes the NYT seriously anymore.
- kbutler 10y ago> when they see an article stating scientists say that climate change is worsening, they will view it just like any article that has "scientists say" in the title. Actually, you should see it exactly the same way - a possibly interesting finding from probably a single study, and if you actually want to know the scientific information behind it, you should go read the science, not the newspaper, and look at multiple studies, and look for weaknesses in the study that may weaken the findings. ...especially if it is something you already believe.
- 10y ago
- bitwize 10y agoIn other words, to garbage-collect.
- theophrastus 10y agoFrancis Crick, (of Watson and Crick DNA fame), got very interested in brain science toward the end of his life and gave several worldwide lectures on that subject. I was fortunate to attend one of them. During which he proposed several interesting theories. My favorite being that the purpose of dreaming was to identify and collect all the well-separated bits of something designated to be forgot, (tracing the chain of fragmented memory blocks); exactly as you suggest: the biological equivalent of garbage-collection.
- organsnyder 10y agoThat was my immediate thought, as well. It even behaves similarly: If you allow the system time to garbage-collect before it's absolutely needed, it's less intrusive. If you go too long, you'll end up doing a garbage collection cycle without advance warning.
- trendia 10y agoDamn, it'd be nice if our brain were stack-based and automatically called destructors.
- Klockan 10y agoThat would be nice till you accidentally buffer overflow and writes garbage over your entire brain.
- easy_rider 10y agoSurely it's not the other purpose. How about recovery and healing processed?
- sametmax 10y agos/other/only I guess. Yeah, global maintenance of the mind and body is more like it.
- alphonsegaston 10y agoIf so, then what function do dreams have? Are they akin to zero-filling a disk?
- randomdata 10y agoPerhaps dreams are the mechanism that allows the dimensionality reduction to take place? Or at least a side effect of us becoming semi-conscious while the process is taking place?
- rjuyal 10y agoThat's just a screensaver.
- tprice7 10y agoAs someone with no neuroscience background I’ve suspected this for a while just based on how Boltzmann machines work. These are a type of unsupervised artificial neural network. The training algorithm for Boltzmann machines has two phases: 1. (Awake phase) Feed the network training data, and increase the weights between neurons that tend to get activated simultaneously in this phase. 2. (Dreaming phase) Let the network run without any training input, and decrease the weights between neurons that tend to get activated simultaneously in this phase. This training algorithm wasn’t designed to emulate how human brains work, it just sort of falls out of the math. And yet (1) resembles the Hebbian principle from neuroscience (neurons that fire together, wire together), and (2) resembles the process described in this article. Actually I suspect something stronger than what the article claims based on this: that the connections that get pruned are the ones connecting neurons that fire together while dreaming. It would be nice to have someone who knows stuff about neuroscience comment on this.
- dontreact 10y agoI wouldn't be so sure that Boltzmann machines were designed without how the brain operated in mind. Terry Seknowski, one of the inventors, is a computational neuroscientist. In general, I think the influence of neuroscience on neural network research has been subtle and perhaps underrated. For example, modern day convolutional neural networks Havea lineage going back to Fukushima's neocognitron, which was heavily inspired by Hubel an Wiesel's simple/complex cell model of visual cortex based on single cell electrophysiology.
- tprice7 10y ago"I wouldn't be so sure that Boltzmann machines were designed without how the brain operated in mind." Sure, actually it seems highly unlikely to me that they were designed without considering at all how they brain works. Let me clarify what I meant: given the definition of how a Boltzmann machine infers (i.e. how to determine which neurons are on or off), the training algorithm can be derived from purely mathematical considerations.
- 10y ago
- majkinetor 10y agoNot convincing for me. While forgeting might be one of the effects that happens it is certainly not the main purpose of sleep. If you forbid people to sleep long enough they die and nobody knows why (not counting microsleeps). Fatal Famililal Insomnia is erm.... fatal. Its certainly not because you didn't forget. You can use alternatives for that, such as boosting endocanabinoid system. THC in mices also make them forget stresfull events in life and vice versa (blocking CB1 receptor makes them remember). There is strong anecdotal evidence that it happens in all human consumers too. Also, there are few people that can never forget [1], one depicted in House MD episode and those people sleep and I bet they would still die if they didn't. All those facts do not align in my mind with above stated hypothesis. AFAIK, some neural pathways get improved during the sleep while others are pruned. That sounds more like a brain is in a maintenance mode, filtering out irrelevant stuff from important (among other things that might happen). [1] http://discovermagazine.com/2006/jun/j-woman-memory http://discovermagazine.com/2006/jun/j-woman-memory
- roywiggins 10y agoIt's possible Fatal Famililal Insomnia kills you by some other mechanism, and the sleeplessness is just a symptom, I figure. I don't think we know that the sleeplessness is the thing that kills you. "Like all prion diseases, FFI is a progressive neurodegenerative disease, which means over time there are fewer neurons (nerve cells). Loss of neurons in the thalamus, as well as other mechanisms not yet fully understood, cause the symptoms of FFI." "Although the main target of FFI is the thalamus, other parts of the brain are affected as well including the inferior olives. The inferior olives are part of the medulla oblongata and are important for coordinating our movements (motor control). Losing neurons in the inferior olives can make it harder for a person to control their movements as seen in later stages of FFI." https://rarediseases.info.nih.gov/diseases/6429/fatal-familial-insomnia https://rarediseases.info.nih.gov/diseases/6429/fatal-famili... When your whole brain is going haywire due to neuron loss, attributing death to sleeplessness seems premature.
- majkinetor 10y ago> When your whole brain is going haywire due to neuron loss, attributing death to sleeplessness seems premature. Or it could be another way around, as its not easy to have experiments like this I guess we can never know. But yes, that is certainly possible that in FFI you die due to some other reason. I didn't see that info you provided but I remember reading in NGeo many years back that FFI people seem healthy in other aspects. There was 1 experiment with mices tho - after 32 days they all died witout sleep: [1] http://health.howstuffworks.com/mental-health/sleep/basics/die-if-never-sleep.htm http://health.howstuffworks.com/mental-health/sleep/basics/d...
- JoeAltmaier 10y agoI'm thinking its more like, to integrate memories. Lessen the impact of the most recent memories lest we lose earlier lessons. Kind of like a moving average or filter. Dim traumatic events so we can think about them without over-reacting.
- eitally 10y agoEvery parent probably intuits this, whether they consciously realize it or not. The #1 cause of babies crying [that isn't pay or hunger]: overstimulation & a need for sleep to "reset".
- tossaway1 10y agoI think most would intuitively attribute that to sleep restoring energy levels so the baby feels better, not anything to do with memory.
- majkinetor 10y agoThe main reason is probably is need to be calm while the body is experiencing that level of growth. You wouldn't want to build a house with constant earthquake I guess.
- neaden 10y agoWhat's the animal with the least brain that sleeps? Jellyfish apparently take prolonged rests on the sea floor which is a kind of sleep.
- chc 10y agoIf you count that as a kind of sleep, then it would surely be them, since you can't have less brain than a jellyfish.
- givan 10y agoAnybody that studies Carl Jung work on dreams will understand how superficial this theory that tries to explain sleep as forgetting is, and how this theory fails to account for symbols and archetypes that show in dreams, also any event can be remembered by hypnosis so nothing is really forgotten with sleep.
- blueprint 10y agoYou're assuming dreams originate from in you rather than them being something that is reflected on your (sleeping) consciousness. Kind of similar to presuming the brain is what fundamentally generates consciousness.
- allemagne 10y agoIs there some sort of formal research on symbols in dreams, or on dream interpretation in general? I am certain that the vast majority of my dreams are very intricate allegories, but it doesn't feel like a very scientific or testable belief.
- gowld 10y agoAlso they will understand how this work is scientific and not psuedoscientic falsehoods.
- scotty79 10y agoSince I learned that lack of sleep causes hallucinations I though sleep exists to avoid neural network overfitting.
- faceyspacey 10y agoIf you trust your intuition, you've known this is one of the MANY purposes of sleep for a while now. The western science culture of needing scientists to validate what you know as true damages our own ability to trust ourselves. You're not going to have statistical and scientifically proven evidence for 99.99% of most things you encounter in your daily life. That's why the mindset of waiting around for science to prove something is harmful. You need to be able to go with your own intuition most of the time. Anyway, this was obvious. And keep in mind, it's just one of the purposes--can things not have multiple purposes??
- stouset 10y agoGetting science to confirm what we "know" is the only way to keep our fallible human biases based on our fallible and imperfect human senses in check.
- gnaritas 10y agoOne of the great findings of science is that you think you know is usually wrong. Intuition is a terrible means of understanding reality.
- majkinetor 10y agoYet, it works for some people WAY better then for others.
- stouset 10y agoOkay, but now you need an intuition for whose intuition is accurate.
- gus_massa 10y agoLet's pick some intuitive false facts: * The lack of inertia is very intuitive. Once you stop pushing something it will get to rest soon. This is extremely intuitive. (Unless you live nearby a frozen lake???) * The spontaneous generation of small creatures like worms and flies is intuitive. You put some crap and wait a while, and you'll get a few small animals. (Did someone ever believe that elephants were generated spontaneously?) * Leeches are good for your health. I'm not even sure that this was intuitive, or that it was even a popular cure, but it was used in traditional western medicine. Modern medicine use penicillin, I don't think that using an extract from a mold is intuitively good.
- aftbit 10y agoMy second favorite quote from the Kingkiller Chronicles: >First is the door of sleep. Sleep offers us a retreat from the world and all its pain. Sleep marks passing time, giving us distance from the things that have hurt us. Full quote: https://www.goodreads.com/quotes/156661-perhaps-the-greatest-faculty-our-minds-possess-is-the-ability https://www.goodreads.com/quotes/156661-perhaps-the-greatest...
- majkinetor 10y agoMeh... dreams can be very nasty and hurtful. When I dream bad, I am frecked up entire day.
- auvrw 10y agothe article title (and indeed, upon groggy inspection, the article itself) is misleading: it's likely the the _hypothalmus_ "forgets" while the the _cortex_ "remembers"/"learns" during sleep. i think ppl have been generally aware of this since the 80's
- burtonator 10y agoThis article suffers from the single cause fallacy. Sleep exists, and evolved for multiple reasons.
- jaequery 10y agothis study seems to contradict people being more forgetful when not getting enough sleep
- LanceH 10y agoI went through a 3 week period of sleeping no more than an hour a night, if at all. Things like "this morning" became very muddled. If I thought about what I had for breakfast, there was no difference between breakfast today and yesterday and even a couple days before that -- they were recalled to mind equally. Multiple days in a row felt like "today." It's hard to describe the feeling because I've never felt anything like it before or since. It just felt like the stack was overflowing for "today". One night of sleep and things were back to normal.
- reitanqild 10y agoI went through a 3 week period of sleeping no more than an hour a night, if at all. Can you explain why this happened? Off the top of my head it is either military or having a child, but I have a feeling there might possibly be an even more interesting explanation.
- tcoff91 10y agoCould also be a manic episode.
- reitanqild 10y agoDidn't think of that. Hope my original question didn't come off as rude, I'm just seriously interested how this is possible since I have trouble just pulling a single all-nighter :-|
- LanceH 10y agoI was stationed shard ship for a time. Returning to the mainland, I just couldn't sleep. While aboard, with the general him and rocking, I slept very well. It never happened again after subsequent returns from ship.
- jfaucett 10y agoThe whole premise of there being a single function or main function of sleep seems slightly far-fetched IMHO. For example, is the brain's function to think rationally? To speak and understand language? To unconciously regulate bodily functions? Wouldn't it be more likely that due to the brain's multifunctional nature that an evolutionairly pruned process has developed which encompasses multiple necessary subroutines (energy preservation, memory consolidation, waste cleansing, etc.)
- deegles 10y agoIt seems like forgetting is more of a side-effect than a purpose. I thought of some more headlines in this vein: "The purpose of fire? To create CO2, Scientists Say" "The purpose of exercise? To Sweat, Scientists Say" "The purpose of music? To Make Noise, Scientists Say"
- Frenchgeek 10y agoReplace "Scientists" with "Journalists" and you got it.
- supermatt 10y agoThis sounds like defragmentation for the brain
- state_less 10y agoWhile I prune at night, I keep waking up to this strange american dream.
- pizza 10y agoreposting a comment I made a while ago @ https://news.ycombinator.com/item?id=11327157 https://news.ycombinator.com/item?id=11327157 ----- Very relevant PubMed article many of you will undoubtedly find interesting: "Partial sleep in the context of augmentation of brain function." Abstract: Inability to solve complex problems or errors in decision making is often attributed to poor brain processing, and raises the issue of brain augmentation. Investigation of neuronal activity in the cerebral cortex in the sleep-wake cycle offers insights into the mechanisms underlying the reduction in mental abilities for complex problem solving. Some cortical areas may transit into a sleep state while an organism is still awake. Such local sleep would reduce behavioral ability in the tasks for which the sleeping areas are crucial. The studies of this phenomenon have indicated that local sleep develops in high order cortical areas. This is why complex problem solving is mostly affected by local sleep, and prevention of local sleep might be a potential way of augmentation of brain function. For this approach to brain augmentation not to entail negative consequences for the organism, it is necessary to understand the functional role of sleep. Our studies have given an unexpected answer to this question. It was shown that cortical areas that process signals from extero- and proprioreceptors during wakefulness, switch to the processing of interoceptive information during sleep. It became clear that during sleep all "computational power" of the brain is directed to the restoration of the vital functions of internal organs. These results explain the logic behind the initiation of total and local sleep. Indeed, a mismatch between the current parameters of any visceral system and the genetically determined normal range would provide the feeling of tiredness, or sleep pressure. If an environmental situation allows falling asleep, the organism would transit to a normal total sleep in all cortical areas. However, if it is impossible to go to sleep immediately, partial sleep may develop in some cortical areas in the still behaviorally awake organism. This local sleep may reduce both the "intellectual power" and the restorative function of sleep for visceral organs. https://www.ncbi.nlm.nih.gov/pubmed/24822040 https://www.ncbi.nlm.nih.gov/pubmed/24822040
- blazespin 10y agoMan, I have to ask, how the hell does something like this actually evolve.
- bbrian 10y agoI frequently recommend the Foundational Falsehoods of Creationism (AronRa) videos on YouTube. They're obviously more about addressing creationism, but it's enjoyable and educational and necessarily explains a lot about evolution that I didn't know previously. One great part is where he explains the lineage of species by using folders on Windows. https://www.youtube.com/playlist?list=PL126AFB53A6F002CC https://www.youtube.com/playlist?list=PL126AFB53A6F002CC
- stevehiehn 10y agoHaha, So basically its saying brains use the old JVM 'Stop the world' garbage collector?
- georgeecollins 10y agoPeople have speculated that sleep is meant to organize your thoughts for years. I know when I worked in a Neuroscience lab years ago that is what many researchers thought. But to say it is to "Forget" is almost certainly an over simplification. It might be to optimize to remove the extraneous, but that is probably not all of it either. Nothing about how the brain works is simple.
- haberman 10y agoFor a theory of sleep to convince me, it would need to explain how the benefit from sleep can possibly be worth the huge disadvantage of leaving yourself completely vulnerable for hours a day. Evolution-wise, that seems hard to justify. A variant of human that didn't have to sleep seems like it would overrun the sleep-needing humans, unless the non-sleeping human just isn't possible.
- myf01d 10y agoMy only complaint is that we sleep only 6-9 hours, oh god it should have been 20-22 hours
- mratzloff 10y agoRemember that sleep evolved very early on. Arthropods (insects, arachnids, crustaceans, etc.) sleep. Worms experience a sleep-like state. It's even been shown that cyanobacteria experience circadian rhythms. Fruit flies whose sleep patterns were disrupted were slower to learn new things and faster to forget the things they learned. I'm not sure there is a single purpose for sleep, but memory is certainly a critical factor.