Chronic sleep deprivation stimulates appetite for sweet and greasy snacks

Sleep deprivation whets the appetite for chocolate and fast food

Not enough sleep is unhealthy: lack of sleep not only increases the risk of cardiovascular disease, but can also promote obesity. Scientists from Cologne have now researched why that is.

Lack of sleep endangers the health

That lack of sleep is unhealthy, has already been proven in numerous scientific studies. Not only does it cause constant fatigue and high blood pressure, but in many cases it can even cause diabetes and heart attacks. In addition, you can get fat through lack of sleep, because with too short sleep cravings for fatteners such as fat and sweet snacks sets. This has already been shown by previous studies. A new study has now shown why our self-control is weakening in this state.

People who sleep too little often develop a craving for sweet and greasy snacks. Researchers have now investigated in a study why this is so. (Image: happy_lark / fotolia.com)

Why wake up after a short night of cravings

Recently, an international research group reported that sleep deprivation increases the risk of obesity.

Other studies have shown that you get fat faster when you sleep too little.

This also has to do with the phenomenon of waking up to cravings for chocolate, burgers and other junk food after too short a night.

So far, a hormone balance out of balance was the reason for the strange - and unhealthy - connection.

However, as researchers from the University of Cologne now report in the journal "Journal of Neuroscience", the "tiredness appetite" could also arise quite differently.

The researchers found evidence that sleep deprivation activates the reward system in the brain and stimulates the appetite for greasy snacks.

Disorganized hormone balance

Epidemiological studies have shown that people with chronic sleep deprivation are at increased risk for obesity or type 2 diabetes.

So far, the hormone balance was often seen as the cause. It is believed that the hormone balance is disturbed by too little sleep and as a result of the cravings for fatty or sweet food is awakened.

However, this assumption has now been put to the test by a team led by Julia Rihm, who works in the field of biological psychology at the University of Cologne.

"Our findings suggest that increased food evaluation after sleep loss is more likely due to hedonic rather than hormonal mechanisms," the study authors write.

Joint analysis of three factors

To reach their conclusions, the scientists invited 32 healthy, slim men to the lab, where they were served dinner on two evenings several days apart.

Thereafter, the subjects were instructed to either go home and sleep or stay in the lab, where they were kept awake.

The morning after, all participants in the MRI tube recorded brain activity as they worked on a task.

According to the information, the men should explain how willing they are to pay for certain snacks or non-foods.

In addition, the study participants were bled to measure the hormone levels. Furthermore, they should rank their hunger on a scale.

For Jan Peters of the University of Cologne, the joint analysis of these three factors is so special about the study.

"We have both hormonal changes as well as the influence on behavior and effects on the brain collected," said the co-author of the study in conversation with the German Press Agency.

Subjective value of food

The researchers 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 experimental groups (after all, the subjects had to live without food during the sleepless as well as the restless night), nevertheless, a clear difference emerged:

According to study authors, those with sleep deprivation were more willing to spend more on snacks than on non-foods.

"This effect could be expected on the basis of previous studies," says neuroscientist Peters loud dpa.

But as the blood analyzes showed, hormones are not responsible for that. The MRI scans showed increased activity in two brain areas.

On the one hand in the amygdala, which is located in the temporal lobes of the brain and belongs to the limbic system, and on the other in the hypothalamus, which lies in the midbrain.

According to the researchers, just one night of sleep deprivation triggers a cycle that sets in motion an eating-specific, neuronal reward system.

For the test persons, the snack offer acts as a reward stimulus to which the limbic system reacts, and especially here the amygdala, which processes sensations of affect or pleasure.

No concrete recommendations for action

According to Jan Peters, further attempts must be made to understand why these regions are more activated in people who are over-night.

With recommendations for action, however, the expert retains the view of the results of the investigation.

"Apparently it is in cross-section so that little sleep increases the risk for a whole range of health problems, which includes obesity," says Peters, according to dpa.

According to the scientist, the new study is another building block to explain the relationship.

"We are now a little closer to understanding which mechanism at the neuronal level triggers this behavior and which may play a minor role," said Peters. (Ad)