I am a student in a cram school the workload is high so we have long classes and i have noticed after the fourty five minute lunch break eating satisfactorily in the air conditioned room i am fine and active and productive but on holidays when i am in the hostel room with the warm sunlight through the windows and after i have had my lunch the lethargy increases drastically, i cant seem to keep my head level and lying down feels very natural relaxing and having had that mindset it renders my productivity and i cant study, but my question is why does my lunch make me lethargic on holidays and not on working days, can i attribute this to the temperature of the two places or is there something else?
Adenosine levels in the basal forebrain rise as sleep debt builds up, and then fall rapidly during the subsequent sleep period. Adenosine is created over the course of the day, as a natural by-product of using up our internal energy stores (it forms the core of adenosine triphosphate (ATP), the energy-storage molecule that powers most of the biochemical reactions inside cells). This supports the theory that the body’s regular desire for sleep stems, at least in part, from the brain’s periodic need to replenish low stores of energy. - https://www.ncbi.nlm.nih.gov/pubmed/21401496
Some experts have hypothesized that animals (humans included) have built-in “vigilance signals” that keep them awake and alert when hungry. These signals help them locate and acquire food. It follows that once an animal (or a human) has eaten a lot, these vigilance signals dissipate and are replaced by feelings of fatigue. - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5519825/
Moreover, a neuropeptide orexin/hypocretin regulates both sleep and feeding, providing a strong molecular evidence for the link between feeding and sleep. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4091210/