Sleep And Hunger: The Brain's Control Over Appetite

Many people don't feel hungry after waking up from sleep, even if they've eaten nothing for hours. This is because the body enters a fasting state after a few hours of digestion, during which the liver maintains the concentration of sugar in the blood by releasing small amounts of glucose from its glycogen stores. This is why you might not feel as hungry when you wake up as you did before going to bed.

The hormones leptin and ghrelin also play a role in regulating appetite. Leptin decreases appetite, while ghrelin increases it. Sleep affects the levels of these hormones, and insufficient sleep can trigger the release of ghrelin, making you feel hungrier.

The body enters a fasting state after digestion is complete

The human body enters a fasting state as soon as the process of digestion is complete. This usually happens around 3 to 4 hours after a meal. During this fasting state, the liver maintains the concentration of sugar in the blood by releasing small quantities of glucose from the glycogen it stores within itself. This is why you don't feel hungry when you wake up, even if you went to bed hungry.

The body's metabolic processes slow down when we sleep, but they are still functioning. Our body goes into a repair and restoration mode, building muscle mass, converting protein to muscle, and repairing damaged tissues. This means that our body is still performing several functions and requires energy to do so. However, the energy expenditure is minimal due to the lack of physical activity during sleep.

The feeling of hunger is regulated by the hormones leptin and ghrelin. Leptin, released from adipose tissue, suppresses hunger, while ghrelin, released from the stomach, increases hunger. Sleep duration and quality influence the levels of these hormones, and therefore, our appetite. Longer sleep duration results in higher leptin levels, reducing our appetite. Conversely, inadequate sleep can trigger the release of ghrelin, increasing food cravings and the feeling of hunger.

Additionally, our body's need for food can be influenced by the circadian clock. Our metabolic rate and brain temperature are lowered during non-REM sleep, which is when most of the repair and restoration processes occur. Studies have shown that sleep deprivation leads to decreased leptin levels and increased ghrelin levels, resulting in increased hunger and cravings for carbohydrates and salty foods.

In summary, the body's fasting state, the liver's role in maintaining blood sugar levels, the reduced energy expenditure during sleep, and the regulation of hunger hormones all contribute to why we don't feel hungry while sleeping, even if we went to bed without eating.

The liver maintains blood sugar levels by releasing glycogen

The human body's blood sugar levels are primarily regulated by the hormones glucagon and insulin. When we eat, our blood sugar levels rise, prompting the pancreas to secrete insulin. Insulin signals to the liver that blood glucose levels are high, causing the liver to absorb glucose and convert it into glycogen for storage. This process is called glycogenesis.

Glycogen is a form of glucose, which is the body's main source of energy. The liver stores glycogen for later use when the body needs it. When we are not eating, especially overnight or between meals, the body has to make its own sugar. The liver achieves this by converting glycogen into glucose through the process of glycogenolysis.

The liver releases glycogen to maintain blood sugar levels within a healthy range. When blood sugar levels drop, the pancreas releases the hormone glucagon, which instructs the liver to convert glycogen back into glucose. This process raises blood sugar levels and ensures the body has a steady supply of energy.

The liver can also produce glucose through gluconeogenesis, where it manufactures glucose from amino acids, waste products, and fat byproducts. This process occurs when the body's glycogen stores are running low, and the liver needs to conserve sugar supplies for organs like the brain, red blood cells, and parts of the kidney.

The liver's ability to store and release glycogen is crucial for maintaining blood sugar levels and providing the body with a consistent energy supply, especially during periods of fasting or sleep when we are not consuming food.

Sleep affects the hormones that control appetite

Research has shown that sleep deprivation can lead to increased levels of ghrelin and decreased levels of leptin, resulting in higher appetite and hunger. This can also explain why people tend to feel hungrier when they are sleep-deprived, such as during a hangover.

Additionally, the body's blood glucose levels play a role in regulating hunger. When blood glucose levels drop, the liver releases stored glycogen to maintain these levels, reducing feelings of hunger. This process occurs during sleep, which is why people often feel less hungry when they wake up, as their blood glucose levels have been stabilised throughout the night.

Eating a balanced diet can prevent nocturnal hunger

Firstly, it's important to understand the role of blood sugar levels and hormones in regulating hunger. When we sleep, our liver maintains stable blood sugar levels by releasing small amounts of glucose from stored glycogen, preventing us from feeling hungry. However, if blood sugar levels drop too low, the liver's glycogen breakdown can lead to nocturnal hunger. A balanced diet that includes complex carbohydrates can help stabilize blood sugar levels and reduce the likelihood of nocturnal hunger.

Secondly, a balanced diet should include adequate protein and fibre, which promote satiety and reduce hunger cravings. For instance, a 2010 study found that high-protein meals reduced night-time eating desires by 50%. Including protein-rich foods like lean meats, fish, eggs, dairy, legumes, and nuts in your diet can help you feel fuller for longer and reduce the urge to eat at night.

Thirdly, maintaining a consistent eating schedule with three meals and healthy snacks can prevent nocturnal hunger. Skipping meals or fasting for extended periods can disrupt your body's natural rhythm and lead to intense hunger cravings at night. By spacing out your meals and including nutritious snacks, you can stabilize your blood sugar levels and reduce the likelihood of nocturnal hunger.

Additionally, it's important to be mindful of the types of foods you consume. Highly processed, sugary, and fatty foods can lead to unhealthy eating patterns and increased nocturnal cravings. Opting for healthier alternatives, such as whole grains, fruits, vegetables, and lean proteins, can help you feel satiated and reduce the urge to binge at night.

Finally, staying hydrated is crucial. Sometimes, thirst can be mistaken for hunger. Drinking adequate water throughout the day and before bed can help curb nocturnal cravings and promote a good night's sleep.

In summary, eating a balanced diet that includes complex carbohydrates, lean proteins, fibre, and healthy fats can help stabilize blood sugar levels, promote satiety, and reduce nocturnal hunger. Maintaining a consistent eating schedule, choosing nutritious foods, and staying hydrated are also key components of preventing nocturnal hunger.

Not eating before bed can negatively impact your mood

Not eating before bed can have a negative impact on your mood the next day. This is because hunger pains can keep you from falling asleep and even wake you up in the middle of the night. As a result, you may wake up feeling drained, which can lead to binge eating throughout the day.

However, eating the wrong foods before bed can also mess with your mood. Eating foods that are too high in sugar or refined carbohydrates can cause an insulin spike, followed by a drop in blood sugar. This, in turn, will cause a cortisol surge to raise blood sugar levels back up, and you may wake up with a racing heart and anxiety.

The best way to avoid this is to eat a light snack of about 200 calories before bed. This will be enough to curb hunger without disrupting your sleep. Foods such as whole grain bread, whole wheat pasta, mangoes, bananas, or grapes are good options, as they contain tryptophan. Tryptophan is an amino acid that is converted into serotonin, which makes you feel calm and sleepy.

Other good snacks include a slice of turkey with an apple and almond butter, a pear with peanut butter and cinnamon, raw milk cheese with sliced cucumber, or berries with whole plain yoghurt. Pumpkin seeds are also a great snack option, as they are a great source of tryptophan and zinc, which can help improve your mood and sleep.

Frequently asked questions