31 mai Long ago, these foods would have mainly been fruit
Stuart's observations explain these mysteries. All four observations (liking for sweetness, separation of main course and dessert, sweet things taste bad when hungry, dessert after dinner but not lunch) make sense if we have evolved mechanisms to push us to eat sweet foods near bedtime. Because sleep is so important for health, there would be powerful selection for anything that improved sleep.
Basic physiology
4. The brain runs on glucose. In my brain tests, sugar drinks, cupcakes, and other sugar-rich foods make an obvious difference 30 minutes to 2 hours later. (I get faster.) And the brain controls sleep, an enormously complicated and time-sensitive process. Too little blood sugar during sleep could easily disrupt sleep.
5. Basic nutrition. Honey is half glucose, half fructose. When you eat it, the glucose enters the blood quickly and would supply glucose to the brain in the first half of the night. In contrast, the fructose turns into glucose and enters the blood slowly (fructose has a low glycemic index). This would supply glucose to the brain in the second half of the night. Many fruits, such as bananas, figs, and grapes, have a similar composition (similar amounts of fructose and glucose). Most fruits have plenty of fructose and glucose. A glucose/fructose mixture makes honey near the start of sleep a good source of blood glucose over an extended period without food. Notice that you need both - glucose and fructose - in roughly equal amounts to get a roughly steady supply over six or seven hours.
6. Basic engineering. When you are asleep, there can be no “course correction”. You must subsist for the next six or so hours without any behavioral help, such as drinking water when thirsty. So it makes design sense to do something shortly before sleep that will provide a relatively steady supply of glucose throughout the night (“time-release”). That won't be a lot of glucose at once. You need a food that is a mix of sugars.
