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Eating when you're tired isn't a new thing, but why does it happen?

When you’re tired, or haven’t got enough sleep, it’s safe to say that a few strange things happen to you that wouldn’t normally because your body is certainly not operating at its peak level.  

But apart from tiredness making it harder to train and difficult to concentrate, you also need to deal with the fact that you are more likely to binge eat on unhealthy fast foods rather than healthy ones, and it’s all down to science to explain why.

Recent research at UC Berkeley using functional magnetic resonance imaging (fMRI), scanned the brains of 23 healthy young adults, first after a normal night’s sleep and next, after a sleepless night. They found impaired activity in the sleep-deprived brain’s frontal lobe, which governs complex decision-making, but increased activity in deeper brain centers that respond to rewards. Moreover, the participants favoured unhealthy snack and junk foods when they were sleep deprived.

And it’s all down to not getting enough sleep. The rationale behind this is that if your decision- making ability is impaired or not functioning as it should be then you’ll be more likely to make poor food choices that are based on impulse rather than being well-thought out.

But why does this happen? To understand why we get so hungry and make poor food choices when we are sleep deprived we need to understand how our hunger hormones work.

We previously dove into the role that hormones play in hunger and we can look into two of the main hormones, leptin and ghrelin, to further understand why the role that they play coupled with sleep deprivation leads to us being more likely to binge on food when we’re tired.

For people who want to stop craving food so much, an increased amount of leptin would be what you’re looking for, but it’s not as easy as that. Leptin is primarily secreted in adipose tissue (fat), as well as a few other parts of the body. It moves through the circulatory system and eventually into the hypothalamus where it tells your body that you have eaten enough, thus decreasing your desire to eat.  

It is meant to tell the body that it has too much fat, but in some cases, as research has found in people who are obese, leptin is increased, whereas surprisingly, the level of ghrelin is decreased. Studies have now established that obese patients are leptin-resistant and that their bodies do not trigger the same response signalling satiety as people who are not obese.  

Sadly, it appears that this may be a function of the society that we live in today. It is suggested that what you get is an increased desire to eat. Therefore, if you would like to lose weight then you also need to combat your innate body responses and force yourself to become acclimatised to a different way of eating, rather than eating according to every hunger pang.

Conversely, Ghrelin is secreted primarily in the lining of the stomach, and it is this hormone that increases hunger and stimulates our appetite, therefore telling us when it is time to eat. There are a number of other factors at play, but right now it is thought that ghrelin moving through your bloodstream is responsible for that feeling when your stomach clenches and you need to get food in right away.

Research shows that your stomach makes ghrelin when it’s empty. Just like leptin, ghrelin goes into the blood, crosses the blood-brain barrier, and ends up at your hypothalamus, where it tells you you’re hungry. The issue with this is that if your hormonal balance differs from another person’s, you will be more prone to react when the ghrelin kicks in, even at an amount that another person may be able to easily deal with.

It could be that ghrelin could be secreted due to external factors as well. If you see something that you desire, reminded of the taste of a pizza or sushi, then your brain goes into overdrive and forces you to eat when it isn’t necessary. This process of overeating can lead to you increasing the amount of adipose tissue you have, while making you leptin-resistant. It’s a vicious circle but one that can be actively controlled through sheer willpower.

The issue that comes with these hormones is that when we’re tired, higher levels of ghrelin is released, while leptin is lowered. This means that we are less likely to feel satiated and will feel hungry while in reality we just need to get a good night’s rest. You should still ensure that you do not go to bed hungry but make quality food choices and do not overeat so that eating so late at night won’t negatively affect you in the long term.

A 2016 study also found something else that plays a role in our food choices and sleep named the endocannabinoid (eCB) system. Their findings suggest that activation of the eCB system may be involved in excessive food intake in a state of sleep debt and contribute to the increased risk of obesity associated with insufficient sleep. This increased risk is due to our food choices as well as our metabolism at times when we should be at rest.

One thing is for certain, there are a lot of factors at play but for the same reason sleep should always be viewed as just as important as your nutrition and fitness. Getting enough sleep every night is crucial for a person’s health and insufficient sleep can lead to a variety of complications that will hamper your progress and make it more difficult to reach your goals. 



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