This article is from the Quest magazine. Incredibly annoying, that packing moment after lunch. Where does that dip come from?
There are many stories about the cause of the after-dinner or lunch dip. For example, it is due to changes in blood sugar levels, or because too little blood goes to your brain while digesting a hearty meal. But which theories are true? Why do you get so tired after dinner? And is there something you can do to prevent it?
Fact or fable?
"It is difficult to say very clearly what the cause of the dip is," says Sander Kersten, professor of food sciences at Wageningen University. "Many of the existing theories have also been debunked." Take for example the idea that a lot of blood goes to the stomach after a meal, so that not enough blood would remain for the brain. Kersten: "There is indeed more blood going to your gastrointestinal tract, but your body ensures that the same amount of blood continuously flows to the brain." The brain is therefore not affected by a shortage of blood.
Another idea: low blood sugar after eating would cause you to get tired. "That's also a monkey sandwich. It's true that after a meal your blood sugar level first rises and then falls again. But by the time it is low again, it's four or five in the afternoon."
Around the clock
The most likely cause of the after dinner dip is the biological clock. "You go through all kinds of phases throughout the day," Kersten explains. "Your alertness, blood pressure, heart rate, blood sugar level, temperature, brain function and your metabolism: everything has a rhythm." For example, your body temperature is highest at the end of the afternoon and certain hormone levels are highest in the morning.
"With most people we see a fall in alertness around one or two in the afternoon. That happens to coincide with the period after lunch. It is a natural rhythm that also occurs independently of the meal." You have this valley in your alertness because your body switches from nervous system position.
Two types of positions
You have two: one that works when you are active or stressed and one that you use at rest. Kersten: "Around two o'clock, your biological clock will ensure that the position you use during rest has the upper hand." That can make you feel relaxed or sleepy.
Does your meal have no effect on the dip at all?
"It's an interaction," says Kersten. "You naturally have a clock, but you can also adjust it. Your biological clock also adjusts when you eat."
The same happens if you have a jet lag. Your body has a natural rhythm and when that does not match the rhythm of the outside world, you get confused. But if you are in that rhythm for a while, your biological clock will adjust accordingly. Kersten: "If you skipped lunch once, your dip would be less bad."
Avoid after-dinner dip
If you suffer a lot from the after dinner dip, that is annoying. Kersten has a few tips: "Maybe it helps to eat a little less. Or take measures that can make the dip less difficult. For example, if you only have to listen to someone, you fall away. If something is expected of you, then you are in a state of readiness. "
So ask your boring colleague if he would like to shake up the figures at a different time and go for a walk instead, or take an active part in the meeting. This prevents you from falling asleep in front of all your colleagues.
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