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Deprivation of sleep makes you hungry for chocolate and fast food
Too little sleep is unhealthy: lack of sleep not only increases the risk of cardiovascular diseases, but can also promote obesity. Scientists from Cologne have now researched why this is so.
Lack of sleep is a health hazard
Numerous scientific studies have already shown that lack of sleep is unhealthy. It not only causes constant fatigue and high blood pressure, but is in many cases even the cause of diabetes and heart attacks. You can also get fat due to a lack of sleep, because if you sleep too short, you become hungry for fattening foods like fat and sweet snacks. Earlier studies have shown this. A new study has now shown why our self-control is weakening in this state.
Why you wake up after a short night of cravings
An international research group recently reported that sleep deprivation increases the risk of being overweight.
Other studies have shown that you get fat faster if you sleep too little.
This also has to do with the phenomenon that you often wake up with a craving for chocolate, burgers and other junk food after a short night.
Up to now, a hormonal balance that has become unbalanced has been the reason for the strange - and unhealthy - connection.
But as researchers from the University of Cologne now report in the journal "Neuroscience", the "fatigue appetite" could arise quite differently.
The researchers found evidence that sleep deprivation activates the brain's reward system and boosts appetite for fatty snacks.
Disorganized hormonal balance
Epidemiological studies have shown that people with chronic sleep deprivation have an increased risk of obesity or type 2 diabetes.
So far, the cause of this has often been seen as the hormone balance. It is believed that too little sleep confuses the hormonal balance and, as a result, cravings for greasy or sweet foods are awakened.
However, this assumption has now been put to the test by a team led by Julia Rihm, who does research in the field of biological psychology at the University of Cologne.
"Our results indicate that an increased food rating after sleep loss is due to hedonic rather than hormonal mechanisms," the study authors write.
Joint analysis of three factors
To arrive at their results, the scientists invited 32 healthy, slim men to the laboratory, where they were served dinner on two evenings, several days apart.
Subsequently, subjects were instructed to either go home and sleep or to stay in the laboratory, where they were kept awake.
The morning after, all participants in the MRI tube recorded brain activity while they were doing a task.
According to the information, the men should explain how willing they are to pay for certain snacks or for non-food.
In addition, blood was taken from the study participants to measure hormone levels. Furthermore, you should classify your feeling of hunger on a scale.
For Jan Peters from the University of Cologne, the joint analysis of these three factors is special about the study.
"We recorded both hormonal changes and the influence on behavior and effects on the brain," said the co-author of the study in an interview with the German Press Agency.
Subjective value of food
The scientists found that the subjective value of food compared to non-food is increased by sleep loss.
Although the feeling of hunger should be the same in both test groups (after all, the test subjects had to manage without food in the sleepless as well as the restful night), however, there was a clear difference:
According to the study authors, subjects with sleep deprivation were more willing to spend more money on snacks than on non-food.
"This effect could be expected based on the studies so far," says neuroscientist Peters, according to dpa.
But as the blood analyzes show, hormones are not responsible for this. Rather, the MRI images showed increased activity in two brain areas.
Firstly, in the amygdala, which is located in the temporal lobes of the brain and belongs to the limbic system, and secondly in the hypothalamus, which is located in the midbrain.
According to the researchers, just one night of sleep deprivation triggers a cycle that triggers a food-specific, neuronal reward system.
For the test subjects, the snack offer acts as a reward stimulus to which the limbic system reacts, and above all the amygdala, which processes feelings or feelings that are emphasized by pleasure.
No concrete recommendations for action
According to Jan Peters, further experiments need to clarify why these regions are more activated in people who have stayed overnight.
However, the expert is reluctant to make recommendations regarding the results of the investigation.
"Apparently, in cross-section, little sleep increases the risk of a whole range of health problems, including obesity," according to Peters, dpa.
According to the scientist, the new study provides another building block to explain the connection.
"We are now a little closer to understanding which mechanism at the neuronal level triggers this behavior and which one may play a subordinate role," said Peters. (ad)