Hacker News Reader

Comment by mellow_observer | Hacker News Reader

Since the brain is optimized for low energy environments, and we have now reached a high energy availability era, it makes you wonder if there's a way to get around the mental fatigue problem somehow. Fatigue is incredibly intellectually debilitating and if we could find a way to be fully on all of the time if we so wish, that should come with a great increase in quality of life.

Now available energy is almost certainly not the only reason we have fatigue, so maybe there's other barriers to overcome, but I'm shocked at how little attention this topic gets. In hackernews spirit, if someone could sell a real cure for mental fatigue, you'd change the world

View on HN

At the risk of asking a dumb question, what really is mental fatigue and do all people experience it the same way?

On one hand, I understand -- and feel very directly -- physical fatigue, and the metabolic limitations if I try to say run slowly versus push hard up to my lactate threshold. I am currently training for a marathon, and know to train by following progressively heavier loads of long distance runs, interval training, stretches and rest periods to develop my speed and endurance.

But mental fatigue really just isn't a phenomenon that I personally relate to. I know some people say they can perhaps work 4-6 focused hours in a work day, and that's it. Whereas my brain seems to be able to work at essentially the same intensity for as long as I want it to, up to 18 hours a day, and then I need a bit of sleep to recover. So I don't quite comprehend mental fatigue, or what a cure for it would be. I don't even know how I would increase my ability to avoid mental fatigue other than minimising distractions (like HN!) and just keep thinking more for longer.

How do other people here experience mental fatigue (or not)?

Mental fatigue is something that can manifest in different ways.

To keep it short, for me, It is like I can think down a path, but slowly, it is like I have this plodding speed, if I try to think 'quicker' (or more reactive/agile) it feels like a lot of effort, like I have to focus and push myself. The more effort I apply the more energy I use. The more energy I use the longer this state lasts for. The longer this state lasts for the more chance I develop physical issues. When I am in this state, I can't mentally fit pieces together. It is like I am wearing oven mits and trying to build lego. It just doesn't fit together. oh and I get really clumsy, my movement becomes really uncoordinated.

So it is like I have a smaller pool of energy, and I can spend it slowly over a longer period. Or faster over a shorter period. When I go over my limits, then see above.

The only cure, is rest, and that is usually about 3 days of not pushing myself mentally too hard, to get back to a reasonable baseline. It is improving, if we had had this conversation three years ago...

I have seen this in other devs, a friend of mine has MS and she needs to meter her energy levels like this. My neighbour came out of hospital after a serious illness and she has some of these symptoms. It is more common than you would think.

For me the mental fatigue is mostly related to context switching, being disturbed (slacks, meetings etc but also side quests to the original problem), and working on a fuzzy problem.

Working a few hours in such environment is very fatiguing.

On the other hand, when I work on a single thing, no disturbance, clear problem definition, having all necessary skills to do the thing, I can work 10h and it's not fatiguing.

It depends on the kind of work. If it's routine stuff, past seven hours or so, I can keep going and not feel tired, but I increasingly don't want to, and the feeling that I'd rather be doing something else becomes very distracting. If the work is technical and intellectually rewarding, I might feel inspired to continue, but I start making mistakes and past a certain point, it becomes counterproductive. If the work requires conceptual or creative insights, my brain stops delivering them for free and my backup methods for squeezing them out start failing too. If I'm speaking or writing, I lose the thread and my words lose their punch and personality. My occasional bouts of insomnia bring a different kind of all-encompassing fatigue. I become overemotional. At my most sleep-deprived, I struggle to operate a kettle. Things were different when I was younger. Writing up my PhD, I essentially slept every other night for months, yet stayed sharp, productive.

> Whereas my brain seems to be able to work at essentially the same intensity for as long as I want it to, up to 18 hours a day, and then I need a bit of sleep to recover.

Potential variable explaining this - what's your age? I could do this too in teens/twenties.

> How do other people here experience mental fatigue (or not)?

Just normal tiredness / distraction. Two days of actual full-on active pairing on something tricky and I just want to go to sleep after work.

Mental fatigue is when your brain is tired, but your body is not.

In other words, you don't want to sleep or lie down, you want to stop thinking.

Perhaps fatigue is not limited by energy but by the byproducts of energy usage to do work. It becomes much more complex to tackle if that's the case, instead of finding ways to allow the brain to use more energy when available we would have to mess around with the cleanup processes which are much less well understood.

I don't think we will have a way to "cure" mental fatigue until we more completely understand both the mechanisms behind thinking, as well as resting, and at the moment we barely scratched the surface of them.

One theory about the needfulness of sleep is that the brain uses the period to literally pump toxins out, on a very slow rhythm - minutes of contraction "squeezing" the byproducts out of the sealed environs of the brain to the general body system, where they can be filtered and removed.

>if we could find a way to be fully on all of the time if we so wish, that should come with a great increase in quality of life

In fact what would happen is that it would become the new normal and everyone would be expected to pop the "pep pills" and work 20 hour days. Source: the military.

Perhaps the real increase in quality of life is not feeling the pressure to be "on all the time"?

What if we could be off all the time? Jesus, that would be so glorious.

My layman observation from tons of pop sci consumption is that the rate of metabolism seems to correlate greatly with life expectancy. Running at 100% all the time would likely wear the system out much sooner, e.g. due to higher oxidation and increased cancer risk.

Even if you are correct, the article discusses more efficient thinking as a goal.

If you have to floor the gas to make it out of your driveway, versus owning a well-tuned highly efficient modern car, those are two very different sorts of "metabolism".

Let’s wait for proper research. One mans observation is just that.

I'd be concerned about the side effects. Sounds like burning the candle by both ends

Cocaine?

If you could come up with a ray-gun that give cokeheads mental fatigue, you'd make the world a more peaceful place.

No thanks! I already lived through one ray-gun's war on drugs.

Heh, fair point.

Works for half an hour. Then what?

its a helluva drug

Reply on news.ycombinator.com