Why do we feel sleepy after we eat? There are two components to the so-called “food coma”: neurological and hormonal. When we eat, the food mashed up by your teeth is swallowed down the oesophagus and into the stomach, where it is churned in a vat of very strong hydrochloric acid. The acid dissolves the food into liquid form, which is then sent to the small intestines. Here, the chemical components of the food such as carbohydrates is broken into simpler blocks, such as glucose. This is then absorbed into the bloodstream.
The body can actually sense when you have swallowed food, as your stomach stretches and sends signals to the brain. This triggers the activation of the parasympathetic nervous system (opposite of the sympathetic nervous system, which is the “fight or flight” system). The parasympathetic nervous system is involved in digesting and rest. It stimulates stomach acid production, gut movement and even reduces your energy level so that digestion can happen smoothly. In old people, it can even decrease blood pressure enough to a point that they feel dizzy (much like head rush). This is the neurological component.
The hormonal component is linked with the absorption phase of digestion. To deal with the increasing level of glucose in your blood, the pancreas secretes insulin. Insulin rounds up the glucose in the blood and stores it away in cells to normalise the blood glucose level. In this process, it also stimulates the uptake of certain amino acids (building blocks of protein) into cells. However, it leaves out one type of amino acids called tryptophan. Because there is more tryptophan in the blood compared to the other amino acids, your brain decides to use this to build more proteins. Tryptophan is converted in the brain into a very important neurotransmitter called serotonin, which is then converted into melatonin. Melatonin is a neurotransmitter involved in triggering sleep. Therefore, through this extremely complicated pathway, food causes sleepiness.
At face value, this makes it look like increasing intake of tryptophan may help induce sleep. It is commonly said that turkey meat and bananas help you sleep because of tryptophan. But this is an urban myth as neither of these foods are particularly high in tryptophan and there is no evidence to suggest that tryptophan itself helps you sleep. Then again, melatonin supplements have some evidence supporting it as a sleep aide. This shows just how complicated the human body can be.
In the children’s story Goldilocks and the Three Bears, the protagonist is found trying out various porridges, chairs and beds until she finds the one that is just right for her. Because of this, the name “Goldilocks” has become a symbol for something that is “just right”. A Goldilocks economy is one where there is high growth but no inflation; a Goldilocks planet is one which is not too hot or too cold, making it an ideal planet for life; the Goldilocks effect is when success is achieved because something was not too great or too little.
The Goldilocks effect is a law of nature that is far more important than you would think. Nature always seeks consistency, as shown in the human body. For something as complex as life to exist, a cell must maintain its internal environment in a perfect, ideal state. French physiologist Claude Bernard observed that a cell’s internal environment does not change even with changes in the external environment, and commented that “The stability of the internal environment is the condition for the free and independent life”. This is the basis for homeostasis. Without homeostasis, life cannot exist and all living things put in all their effort in keeping homeostasis. Our body constantly strives to keep various factors such as pulse, blood pressure, oxygen saturation, temperature, blood glucose, electrolytes and numerous hormones etcetera in a stable range. One could possibly argue that the meaning of life is “to maintain homeostasis” – a rather cyclical argument.
To understand the importance of homeostasis, let us look at how changes in the external environment affect us. Our core temperature is maintained in a tight range around 36.5 degrees. If it is altered even a couple of degrees, we exhibit symptoms of hypothermia or hyperthermia. If the weather is too hot, we sweat to cool ourselves; if the weather is too cold, we shiver to raise our temperature. After a meal, we secrete insulin to lower our blood glucose, while we secrete glucagon when starving to raise our blood glucose. Failure of either system leads to either diabetes or hypoglycaemic shock respectively. Homeostasis is an extremely complicated and intricate self-repair system that cannot be imitated.
The Goldilocks effect can be applied beyond physiology to our lives. Everything in moderation; to go beyond is as wrong as to fall short. If we have too little money, it is a problem. If we have too much money, it causes other problems. Whether we work or play, doing too much or too little of either can be bad for us. Medicines become poison in excess and even love in excess becomes obsession. In the marathon that is life, if you run too fast you end up collapsing from exhaustion, while running too slow will mean you never get anywhere.
The secret to happiness lies in understanding what is “just right”.
Diabetes is a common and serious disease that is caused by the body being unable to control the blood sugar (glucose) level, leading to severe organ damage. For example, blood vessel damage can lead to blindness, renal failure, heart attacks or strokes. Diabetes is divided into Type 1, caused by the destruction of pancreatic β-cells (that produces insulin) leading to insulin deficiency, and Type 2 diabetes, where insulin resistance renders the hormone useless. Thus, diabetes is a disease related to insulin. So what is insulin?
Insulin is a hormone that lowers blood glucose. It has the important function of controlling blood glucose levels after a meal. Therefore, a diabetes patient has high blood glucose, which has a toxic effect. As type 1 diabetics cannot produce insulin, they require daily insulin injections. Some type 2 patients also need insulin. But this hormone that saves the lives of diabetics also has a deadly dark side.
Too much insulin leads to hypoglycaemia due to its blood glucose lowering properties. This is the opposite of what happens in diabetes, but is even more dangerous. Although there are in-built autonomic defence mechanisms to prevent this from happening, a high level of insulin can overcome this to cause blood glucose to plummet. A hypoglycaemic patient initially suffers cognitive dysfunction, then sweating and tremors. As blood glucose falls further, the patient begins to convulse, until they fall into a coma and eventually die. This is because the brain heavily relies on glucose for its functions, and a disruption of glucose supply causes it to shut down. Because blood glucose fluctuates much like blood pressure, it is hard to control. This leads to many diabetics accidentally falling into hypoglycaemia, or even losing their lives. Furthermore, insulin is sometimes used by people to cause hypoglycaemia as a means of suicide.
If you see a person convulsing, check around for any hypodermic needles or bottles of insulin. A diabetic patient would have a medic alert bracelet, and if it is a suicide attempt they would have recently injected themselves with insulin. If you think it is hypoglycaemia, you must immediately treat the patient as severe complications can occur in a very short time. The emergency treatment is quite simple – raise the blood glucose. For example, dissolving a spoon of white sugar in the patient’s mouth or making them drink a sugary drink such as apple juice can cause a spike in blood glucose, causing the symptoms to disappear. If their consciousness does not return, you may need to repeat the process until their blood glucose is high enough.
Knowing even a little about insulin and hypoglycaemia may lead to you saving a person’s life someday.