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Eating at different times affects the internal clock
Many people have problems after long flights and suffer from jet lag. Similar difficulties also arise for shift workers when the body has to adapt to changing working hours. Researchers found that shifting meals can also affect the body's internal clock.
The researchers at the University of Surrey in England found that the internal clock of the human body can be affected by a shift in meals. The doctors published the results of their study in the journal "Current Biology".
What is the body's biological clock?
The biological clock of the body (circadian rhythm) is controlled by a so-called master clock, which is present in the human brain and is called the suprachiasmatic core, the scientists explain.
What do the so-called peripheral clocks do?
Various other clocks in the human body are called peripheral clocks. These are essentially molecules in cells that react to signals from the master clock, the experts explain. They help to control certain metabolic functions in that area of the body. For example, these clocks in the liver and pancreas can affect blood sugar levels. This can cause problems with a person's metabolism if peripheral clocks are not synchronized with the master clock.
Light and melatonin have little direct effect on the metabolic rhythms
Researchers already knew that the influence of light at the right time or the use of melatonin supplements can help adjust the master clock in the brain to new time zones, said author Jonathan Johnston from the University of Surrey. But light and melatonin seem to have little direct effect on the metabolic rhythms that are controlled by the body's peripheral clocks, the expert adds. In other words, although a person can adjust their internal master clock to a new time zone by exposing themselves to light at the right time, it does not immediately adjust all clocks in the person's body, the scientists say.
Meal time has a major impact on blood sugar levels
The peripheral clocks that control blood sugar levels also affect how much sugar is removed from the blood and how much is released back into the blood. The way the body processes a meal varies throughout the day, says Johnston. For example, when a person eats late at night, blood sugar levels increase and stay elevated for a long time. This effect can also work in the opposite direction. If we change the time of day when we eat our meals, it also shifts the so-called circadian rhythm of blood sugar levels, the scientists explain.
Doctors monitored subjects' sleep over a period of 13 days
To study the effects of meal timing on the circadian rhythm, the researchers examined ten healthy men over a 13-day period. So they wanted to observe how the test subjects reacted to various diet plans. The men wore monitors to collect data about their sleep, the researchers say.
When were the meals eaten in the trial?
During the first three days of the study, the men received breakfast 30 minutes after waking up, followed by lunch five hours later and dinner five hours later. All meals had the same number of calories and the same amount of carbohydrates, fat and protein, the study authors explain.
Subjects had to endure 37 hours of sleep deprivation
After three days of this type of diet, participants were asked not to sleep for 37 hours. During this time, the lights in the laboratory were kept dark so that the men did not experience the light changes that could signal the time to their biological clocks. Nurses woke the subjects when they started to doze, says Johnston.
After sleep deprivation, the second meal plan began
After this period, the scientists started a new meal plan. This time, the participants were not allowed to eat anything within five hours of waking up, the scientists explain. This meal plan was used for a period of six days, then the 37-hour period of sleep deprivation repeated.
Delayed meal plans lead to changes in the rhythms of blood sugar levels
After the meal plan was postponed for five hours, the rhythms of their blood sugar levels were also postponed for five hours, explains author Johnston. The researchers found that in addition to the observed changes in the rhythm of blood sugar levels, many other components of the circadian rhythms of men did not change. For example, there have been no changes in the normal increases and decreases in melatonin (the sleep hormone) or cortisol (the stress hormone).
Easily adjust to new time zones or work schedules through the time of your meals
The results indicate that the changes observed after the late meal plan were due to changes in the peripheral clocks and not to the so-called master clock, which controls hormone release, the authors say. The new evidence suggests that if you change the time of your meals, you can adapt to a new time zone or work schedule. (as)