This is a "typical mind fallacy check" post. Curious how much (within and without the rationalsphere) people's experience varies.

I generally experience "thinking hard" to be some combination of stressful, headache inducing, and energy draining (sometimes I feel like I actually am burnt out of energy, sometimes I just need to switch tasks). I've talked to other rationalists and they often don't have this experience, and I'm trying to figure out what's going on here.

I specifically experience this when doing conscious, deliberate thought. In particular if it strains the bounds of my current skills, or my working memory. This most often involves thinking strategically in a careful way (i.e. I get this when playing Chess).

When I'm writing characters or imagining talking to people I know (i.e. simulating another person in my head, or pretending to be another person) I also get a headache if I keep it up for over an hour.

I've only talked to a few people about this, so not sure how wide the spread of experience is. But at the very least this varies a bit among people-I-know.

Some hypotheses (or partial hypotheses) so far:

A. Deliberate Practice is straining. Doing deliberate-practice thinking (i.e. straining at the edge of your competence of a skill) is energy draining, and people vary on a) what things strain the edge of their competence, and b) how often they do such things.

B. Straining is wasted motion. Someone I know recently argued that thinking shouldn't drain willpower or otherwise cost resources other than time, and that any time you do that, it's because you're doing some wasted motion. This initially sounded wrong to me. After experimenting a bit I at least believe that much of "draining" thinking is wasted motion that you can learn to skip.

C. People vary in raw cognitive power. Some people may just think faster naturally, or have a higher bandwidth of working memory.

For now, mostly interested in getting a sense of what diversity of experience we have of this on LessWrong. I also suspect there's some research into this somewhere and am curious if anyone either knows about that, or has further thoughts on mechanisms.

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I used to basically never experience this, to the point where I wasn't sure if other people talking about their heads hurting were being metaphorical, but I started experiencing it a year or two ago when I ran up against seriously trying to do math research. But there were aversions in play there.

In general I suspect I've learned to avoid putting my mind in whatever mode causes brain-hurt and I get my thinking done in other ways.

I'm similar here, I only had it once when I was in a team math competition, and I was like "Oh wow, I have an actual headache centring on my temples, that's what people are talking about all the time."

Certain types of hard thinking do this to me, others are invigorating. When it feels like what I'm doing is artificial difficulty or memorization, or is mostly about tracking too many things at once, this will happen. When the complexity level can go arbitrarily high without enough decay in value of information, this will happen. I stopped playing Go because this happened to me when playing, in a way it doesn't happen with basically any other game. Whereas when I do deliberate practice in Magic, or play even a very slow and intense game of Chess, it doesn't happen.

Most annoying is that I get this when I'm trying to code and struggling with syntax or bugs.

I have a revealed preference for maximizing the amount of thinking I can do that doesn't do this and is invigorating, and minimizing the headache-causing type even at very large expense.

Whereas when I do deliberate practice in Magic, or play even a very slow and intense game of Chess, it doesn't happen.

Interesting – does deliberate practice (at least with Magic) for you cause mental fatigue or anything of the like?

As a bit of a self-made expert on headaches, I am pretty sure that it's not the thinking that's causing the headache, but rather unconscious physical tension associated with perceived strenuousness of the activity.

Tension in your neck muscles, temples, jaw, etc. can be practically impossible to notice consciously. You can be totally unaware that you're experiencing it. It can ramp up and initiate a headache quite easily, especially if you're the type of person susceptible to such.

You may have associations between the things your thinking about and stress. Personally, I notice that thinking about stuff that I've been procrastinating on (which I don't really want to be thinking about) feels miserable and manifests itself as physical tension. But I can think intensely about other things for hours without negative effects, if I want to be thinking about those things.

(Edit: Also, if you're "thinking really hard" it's pretty likely that you're sitting in one position for too long. Holding still is shockingly bad for human bodies. We're supposed to be moving around almost constantly. Sitting and staring at one thing for an hour induces an incredible amount of muscle fatigue in the neck, eyes, etc.)

Yeah, the overall update I've gotten from this thread is to install a trigger-action for "notice muscle tension while thinking, relax muscle tension". (At least a fair chunk of my muscle tension while thinking is totally noticeable as soon as I pay any attention)

I've had similar experiences and I think this is part of it.

Eye strain potentially, too.

Yep. Recommended links:

This works super well for me but not everyone I've recommended it to likes it; I'm passing it along anyway because it seems like a safe alternative to deep massage in the back of the head where critical arteries are present:

I perceive several different ways something like this happens to me:

1. If I do something that strains my working memory, I'll have an experience of having a "cache miss". I'll reach for something, and it won't be there; I'll then attempt to pull it into memory again, but usually this is while trying to "juggle too many balls", and something else will often slip out. This feels like it requires effort/energy to keep going, and I have a desire to stop and relax and let my brain "fuzz over". Eventually I'll get a handle on an abstraction, verbal loop, or image that lets me hold it all at once.

2. If I am attempting to force something creative, I might feel like I'm paying close attention to "where the creative thing should pop up". This is often accompanied with frustration and anxiety, and I'll feel like my mind is otherwise more blank than normal as I keep an anxious eye out for the creative idea that should pop up. This is a "nothing is getting past the filter" problem; too much prune and not enough babble for the assigned task. (Not to say that always means you should babble more; maybe you shouldn't try this task, or shouldn't do it in the social context that's causing you to rightfully prune.)

3. Things can just feel generally aversive or boring. I can push through this by rehearsing convincing evidence that I should do the thing -- this can temporarily lighten the aversion.

All 3 of these can eventually lead to head pain/fogginess for me.

I think this "difficulty thinking" feeling is a mix of cognitive ability, subject domain, emotional orientation, and probably other stuff. Mechanically having less short-term memory makes #1 more salient whatever you're doing. Some people probably have more mechanical"spark" or creative intelligence in certain ways, affecting #2. Having less domain expertise makes #1 and maybe #2 more salient since you have less abstractions and raw material to work with. Lottery of interests, social climate, and any pre-made aversions like having a bad teacher for a subject will factor into #3. Sleep deprivation worsens #1 and #2, but improves #3 for me (since other distractions are less salient).

I think this phenomenon is INSANELY IMPORTANT; when you see people who are a factor of 10x or 100x more productive in an area, I think it's almost certainly because they've gotten past all of the necessary thresholds to not have any fog or mechanical impediment to thinking in that area. There is a large genetic component here, but to focus on things that might be changeable to improve these areas:

  • Using paper or software when it can be helpful.
  • Working in areas you find natively interesting or fun. Alternatively, framing an area so that it feels more natively interesting or fun (although that seems really really hard). Finding subareas that are more natively fun to start with and expand from; for instance, when learning about programming, trying out some different languages to see which you enjoy most. It'll be easier to learn necessary things about one you dislike after you've learned a lot in the framework of one you like.
  • Getting into a social context that gives you consistent recognition for doing your work. This can be a chicken and egg problem in competitive areas.
  • Eliminating unrelated stressors, setting up a life that makes you happier and more fulfilled; I had worse brain fog about math when in bad relationships.
  • Eating different food. There's too many potential dietary interventions to list (many contradictory); I had a huge improvement from avoiding anything remotely in the "junk food" category and trying to eat things that are in the "whole food" category.
  • Exercise
  • Stimulant drugs for some people; if you have undiagnosed ADHD, try to get diagnosed and medicated.

I really wish I had spent more time in the past working on these meta problems, instead of beating my head against a wall of brain fog.

For me, thinking hard literally depletes glucose.

I can tell when my blood sugar drops because I get lightheaded and can't think as clearly. I've confirmed that such a feeling corresponds to blood sugar levels using a glucometer, and I feel that way at more frequent intervals (and thus require more snacking) when I'm thinking hard.

I specifically experience this when doing conscious, deliberate thought. In particular if it strains the bounds of my current skills, or my working memory. This most often involves thinking strategically in a careful way (i.e. I get this when playing Chess).


When I’m writing characters or imagining talking to people I know (i.e. simulating another person in my head, or pretending to be another person) I also get a headache if I keep it up for over an hour.

Not sure, but suspect no.

For me this is actually something that cuts me twice. Because it's a signal that I'm hitting the limits of my ability, I then get anxiety on top of the cognitive strain ("what if I'm not good enough to do this?"). This of course both adds to the cognitive strain and causes aversive negative feelings to be associated with the experience.

As an example, I just got done with a Go game where I spent quite a bit of time thinking worried about my performance in an 'even' game, only to realize at the end that I'd gotten beaten embarrassingly badly. This caused a burst of anxiety which forced me to take a break. (Nevertheless I plan to go back and analyze what I did wrong.)

The brain has a constant amount of energy that it burns whether or not we are thinking "hard". On the other hand, "thinking hard" often produces emotional stress. Emotional stress is or results in muscle tension and that tension can lead to headaches.

That's mostly wasted motions. The most targeted way of getting rid of this kind of tensing up I know is the Grinberg method but other somatic approaches like Feldenkrais also reduce the amount of wasted motion that shows as tensing up.

Aside from that there's a phenomenon that's called ego depletion in the literature. I have my own theory about the relating space and I will likely publish a longer posts on it within two weeks from now.

Interesting! I was going to ask some follow up questions, but if you're planning on writing more about it I'll wait for the write ups :)

It doesn't hurt my brain, but there's a brain fog that kicks in eventually, that's kind of like a blankness with no new ideas coming, an aversion to further work, and a reduction in working memory, so I can stare at some piece of math for a while, and not comprehend it, because I can't load all the concepts into my mind at once. It's kind of like a hard limit for any cognition-intensive task.

This kicks in around the 2 hour mark for really intensive work/studying, although for less intensive work/studying, it can vary up all the way up to 8 hours. As a general rule of thumb, the -afinil class of drugs triples my time limit until the brain fog kicks in, at a cost of less creative and lateral thinking.

Because of this, my study habits for school consisted of alternating 2-hour study blocks and naps.

This describes my experience, too: deliberate effort to think about something leaves me unable to direct my thoughts after a while, affects memory, etc..

I can sustain undirected thinking for longer without the same kind of exhaustion although that usually runs out in it's own way and my mind gets quite and stops randomly coming up with thoughts or at least the desire to follow the thoughts that do come up.

Yes absolutely. Its been happening to me ever since high school.

This happens to me too. In particular, if I concentrate at say 95% of ability on a hard problemset for 2+ hours without a break, I'm often "fried" for a few hours after that. In my journals, I sometimes call it "synaptic backlash" — I don't know that it's actually happening on that level, but it feels like I overtaxed some inner mechanism of the brain somewhat.

That said, I think there's a lot of potential explanations. Here's a few I've come up with —

*Actual, physical strain — eye strain, tension in body, staying in same position/posture for long periods of time.

*Forgetting to hydrate or eat while concentrating. (Sometimes I feel like hell after a long work session, and then realize I haven't eaten something in a day, eat, and I'm good again shortly afterwards.)

*Potentially over-consuming stimulants when concentrating — empirically, I go much harder on coffee and nicotine when I'm working on hard problems, but oddly, I seem to forget that I do that. Then I get caffeine/nicotine headaches, but sometimes forget the simple cause-effect relationship of why it happened. (I know that sounds stupid, but I used to do this quite commonly without realizing what it was.)

*General fatigue effects prompting explore/exploit tradeoffs. These two papers on paper that Kaj Sotala shared with me were gamechangers —

Also, a subtle effect that might explain some of it — regular normal homeostatic pressure means we often lose some "cognitive horsepower" throughout the day as sleep pressure builds, circadian/ultradian rhythms cycle, and various biological processes happen. If you're only performing at 60% of your theoretical max capacity, you might not notice a -10% decrease in cognitive processing ability... if you're up at 95% of theoretical max capacity but experience a normal -10% decline as a result of just hours passing, it can feel like you're... I don't know how to describe it, but "losing the problem" or some such... it's likely that at close to our mental limits we more acutely feel the normal loss of cognitive ability that just comes as the day goes on via normal biochemical processes.

That's my $.02 — this is still an active area of inquiry for me, it seems important and relevant to long-term well-being...

I know of exactly two things that do this to me: writing - especially fiction or formal essay writing - and programming. Many mental tasks I don't perceive as effortful; usually if I already know the algorithm to do them it's not usually not strenuous, although it can still be unpleasant in other ways. For some reason, though, writing anything that's more involved than a blog comment or doing programming both feel like they're costing me mental energy.

Yes. Definitely happens to me.

Sometimes it happens because I've been doing something tedious for a long time. Eg. spending 10 hours writing unit tests. Sometimes it happens when I'm thinking hard about something. Eg. learning math. (Unfortunately, I end up experiencing the former more than the latter. Something I plan on fixing.)

My head does feel hotter, although I could just be experiencing that because I am expecting to experience it.

A. Yes. In the research on deliberate practice it states this clearly. It has to be difficult to be getting the most out of it.

Yeah. Something that may not have come through clearly is "I'm re-evaluating whether the descriptions given of deliberate practice (in, say, the book Peak) are actually accurate." The claim is that deliberate practice requires strain. I've recently run into some evidence that more strain might wasted motion than I thought.

So I'm curious how much of deliberate practices is necessarily stressful, and/or are there specific ways it needs to be stressful?

I get something like this occasionally. It happens most often when I'm trying to learn a bunch of foreign language vocab using anki or duolingo.

Same or similar experience here. When I was younger I was aware of the strains of thinking,"harder", "outside the box", "deliberately to explore new concepts or paradigms". As I have recently turned 50 the toll for the same exercises seems much higher and almost debilitating. Memorization and reading have similar effects but not the same degree. Anything creative, analytical, or especially if it's a cross section of the two can be more than tiring but actually physically painful, i.e. headache, "false" eye strain, malaise, even depressive emotional waves, etc. One example might be developing a complex spreadsheet to track, control, measure and record work on a project. Recently the doctor said my blood pressure was just great but that it was still most likely tension or stress causing my headaches.

Raemon, five months later I'm interested to see if you experience any less strain when thinking.

Yes, although I neither tracked it very rigorously nor tried an extensive intervention to fix it. (I periodically attempt to notice when I'm tensing my head while thinking, and it does help, but I haven't remembered to do it reliably when doing thinking that normally strains me)

Cool! I'm updating with a similar tap.

In my experience, thinking hard doesn't hurt my head directly. However, trying to think hard under stress and sleep loss does. Whenever I noticed my head hurts trying to "think hard", it's usually a symptom that something else is going wrong.

It sure feels like I use more energy when I'm thinking hard (but it usually doesn't give me headaches).

I'm having trouble reconciling this with the evidence that the brain uses a constant amount of energy.

The "wasted motion" explanation sounds close, but I sometimes feel drained after a long period of writing code that seemed to involve unusually little wasted motion.

I expect that part of the explanation is my S1 telling me I'm reaching diminishing returns to spending more time on this task.

Thinking hard correlates with feelings of stress, but I suspect they're both caused by having difficult problems, rather than thinking hard causing stress.

No headaches. I probably could play high strategy board games all day and enjoy myself the entire time (I know this extends at least to ~6 continuous hours). I do get tired from other kinds of thinking (reading papers, research) but it doesn't always happen so there's another cause that I don't know yet. If I try to soldier through, I feel uncomfortable and find it incredibly difficult to focus, but it doesn't cause pain.

No headache, but B. sounds closer to my experiences. Consistently doing things I don't want to do and don't understand why it matters makes me less and less inclined to do more of those things and means I have to pay more attention to avoid saying or doing something grouchy. Working on an interesting problem (one that sits just outside my current skill) tends to make me focus more and more, and once I break focus I often find I have aches from bad posture or eyestrain.

Doing a bunch of challenging tasks or working out a lot tends to make me more cheerful and agenty, sitting on the couch grinding levels in an MMO tends to make it harder to break patterns and do challenging tasks. As far as I can tell this is the opposite way things are supposed to work, but it's consistent.

For me, contemplating Zen koans for too long can make my brain "hurt".

Does a dog have Buddha-nature or not? Show me your original face before your mother and father were born. If you meet the Buddha, kill him. Look at the flower and the flower also looks.

I find it interesting because, unlike coding a program or solving a math equation or playing chess, it doesn't seem like koans have a well-defined problem/goal structure or a clear set of rules and axioms. Some folks might even call them nonsensical. So I'm not sure to what extent the notion of (in)efficient optimization is applicable here; and yet it also appears to be an example of "thinking hard". (Of course, a Zen instructor would probably tell you not to think about it too hard.)

They have a well defined structure, they are less exciting once you know it.

My head gets hotter and I do feel some kind of pressure around forehead for "thinking hard under pressure", but I think it's mostly the stress hormones and increased blood pressure / flow / heart rate.

Similar thing for looking at a monitor for many hours straight, but that too may be related to eye muscle strain.

What makes me tired is continued social interaction, especially using several languages. It's fun but tiring. Then it's always nice to hide in toilet or go for a walk or something, to relax and breath a bit, before continuing. That tiredness is definitely related to "thinking hard" tiredness.

EDIT: no headache. My headaches are almost exclusively due to not drinking enough water timely.

The closest thing to this I've seen in the literature is processing fluency, but to my knowledge that research doesn't really address the willpower depletion-like features that you've highlighted here.


I don't get headaches. My mood does plummet after a while, and I get insomnia.

re wasted motion: I think it's rather some sort of cognitive dissonance, ie disagreement between subagents

I have never before encountered the idea of getting a headache from thinking.

My experience with hard problems is that I stare blankly at the problem description for a while, seemingly not thinking of anything much, and then (usually some time later), an idea comes up. It's a bit concerning, to be honest. It might be that I'm just lazy, and don't push myself much? Of course, sometimes I do have an internal monologue of "if I do X will Y happen?", but I don't think it's all that helpful, at least not in the early stages of problem solving. Also, I'm mostly talking about programming problems at work, I don't really play chess, this might not work there, they might just be different kinds of problems.

This mostly matches my experience. By far the most intense version of this I've had was the time I tried to play Chess and Go simultaneously (against two different people). I started sweating and shaking. This seems to suggest that not only is thinking a physical effort, you can push yourself much harder under some conditions than others (just like how deadlifts will physically exhaust you much faster than pushups, even if you push yourself to do pushups as hard as you think you can).