Science Focus (issue 022)

*Yawn* Oh no, your teacher stares at you. You rub your eyes, trying to focus on the differentiation problem your teacher asked you to solve. You start to think, is it the bowl of noodles I had for lunch? Why is it that a food coma hits us so hard every time after lunch? Common Misconception About Food Coma Traditional ly, it is bel ieved that sleepiness after a meal is due to the redistribution of blood flow. We think that blood rushes through the stomach and intestines to facilitate digestion, resulting in a reduction in blood and oxygen suppl ies to our brain and hence the induction of pos t -meal s leepi nes s , medical l y known as postprandial somnolence [1]. However, this is not the case. Blood redistribution theory fails because cerebral blood flow and brain oxygenation are known to be preferentially maintained under a wide range of physiological conditions [2]. They are strictly maintained even during exercise when much of the blood is diverted to muscles; and in fact, a study revealed that there was no measurable change in the blood flow to the brain in carotids after feeding [2]. Therefore, the intake of food wi l l probably not affect brain oxygenation and cerebral blood flow [2]. Lost Lessons – Succumbing to the Inescapable Food Coma 飯氣攻心- 害我們上課睡著的 惡作劇把戲? By Dana Kim 金娥凜