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?