We have a lot of those questions here that base on personal anecdotes and I try to avoid asking any of those. Still, after skipping breakfast and an extremely effective work day so far I started wondering. I have always felt, that for most cognitive tasks I perform best before breakfast. Of course some of it is sure related to being very awake and supposedly having a biorhythm that favours working in the morning, but I have always related this to not having eaten and also surprisingly not feeling hungry at all until basically deciding to eat "because I really should eat something" around noon. So today I decided to find out, if this phenomenon is more widely known or just anecdotal for me. Of course there is a lot of information on how digestion makes you feel tired and you should not expect to be very productive directly after eating. That was not what I am looking for.

Finally I found this 2006 NY Times article about "Empty-Stomach Intelligence", where it is stated that at least for mice being "mildly starving" seems to increase cognitive ability based on the hormone ghrelin targeting not only the hippothalamus, but also the hippocampus. I then tried finding a relevant publication and was only lead to this one, describing the original study about ghrelin influencing food intake, but seemingly not the "sidetrack" of it influencing cognitive abilities during starving.

Now I am lost. Is there any newer publication about this phenomenon that I completely missed, possibly even in relation to how humans can perform cognitive tasks while being mildly starved?

  • $\begingroup$ my guess is following: today people have much more food and food has much more nutritious value than in previous times. So average body is generally running in parasympathetic mode, digesting and resting. That takes attention from CNS, including brain functioning. Mild fasting releases that external pressure. I'd suggest search for link between daily glucose level and brain ability/performance $\endgroup$ – aaaaa says reinstate Monica Jun 10 '15 at 11:09
  • $\begingroup$ Still it is curious for me because it is so counterintuitive. Most people I know if they have to work hard on a cognitive level they tend to snack nuts, chocolate, anything they are used to to keep their attention up. And this does boost your attention for a short while. The mild fasting on the other hand seems to be a more long-term approach (long-term being around 6 hours). $\endgroup$ – skymningen Jun 10 '15 at 11:45
  • $\begingroup$ This question is more suitable for cognitive sciences and I vote to close therefore. I bet it will be well received there. $\endgroup$ – AliceD Jun 10 '15 at 12:12
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    $\begingroup$ I'm voting to close this question as off-topic because it is a well targeted question for Cognitive Sciences. +1 for the nice question :) $\endgroup$ – AliceD Jun 10 '15 at 12:13
  • $\begingroup$ I think it has a biological answer. I vaguely remember reading somewhere that either leptin or ghrelin (or both) have an effect on cognitive performance. Orexins also regulate wakefulness, so they may be part of it as well, as more wakefulness tends to produce better attention, and lots of cognitive ability depends on focused attention. $\endgroup$ – rumtscho Jun 10 '15 at 16:22