The Mystery Of Sleep: Why Don't We Fart?

Farting in your sleep is a common and normal bodily function. While awake, people usually have control over when and where they pass gas, but during sleep, muscles relax and some control is lost. The average person passes gas between 12 and 25 times a day, and most of this occurs while awake. However, certain factors can increase the amount of gas in the digestive system and lead to excessive farting, such as diet, obesity, gastrointestinal problems, and medical conditions.

The body's metabolic state while sleeping

The human body's metabolic state during sleep is a complex process that remains poorly understood. However, it is known that the body's metabolism slows down at night. This means that any food eaten close to bedtime is likely to remain undigested throughout the night and may start to ferment, leading to the pooling of gas inside the colon, which can result in sleep flatulence or morning gas.

The process of creating gas in the body continues while sleeping. This is due to the bacteria in the intestines breaking down undigested foods, such as fibre and certain sugars, and producing hydrogen, methane, and carbon dioxide. Additionally, the body's position in bed can also contribute to the build-up of gas, as lying down allows gas to pool inside the colon.

The anal sphincter, which controls the release of gas, is more relaxed during sleep, and its spontaneous relaxation upon awakening makes it easier for gas to escape. This relaxation, combined with the increased gas production during sleep, can result in morning flatulence or sleep farting.

Furthermore, the body's muscle activity involved in passing gas is inhibited during sleep. This inhibition may lead to a build-up of gas, resulting in more morning gas upon waking up.

While farting during sleep is a normal part of the human experience, excessive or painful gas may indicate an underlying health issue. Therefore, it is important to consult a healthcare professional if you are concerned about the amount or frequency of gas during sleep.

The anal sphincter, its level of relaxation, and rectal pressure

The anal sphincter is a ring of muscle that keeps the anus shut. During sleep, the anal sphincter is more relaxed, and it will spontaneously relax as you awaken, making it easier for gas to escape. This is why people tend to experience morning gas or flatulence in their sleep.

The anal sphincter's level of relaxation is controlled by the nervous system, which sends specific reflexes and messages to allow the sphincter to relax in response to pressure waves in the rectum. The coloanal reflex allows both the internal and external anal sphincter to relax, facilitating the release of gas and faeces. Another reflex, called the rectoanal inhibitory reflex (RAIR), allows only the internal sphincter to relax while keeping the external sphincter closed. This helps with controlling gas and bowel movements.

Rectal pressure is associated with the pressure waves in the rectum that trigger the reflexes controlling the anal sphincter. The anorectal manometer test is sometimes used to assess anal and rectal pressures in individuals with bowel movement difficulties.

While the anal sphincter is more relaxed during sleep, it is still under the control of the nervous system, which inhibits muscle activity and prevents the loss of bowel control while sleeping. However, the gas may still pass, and people may experience more morning gas upon waking up due to the relaxation of the anal sphincter and the accumulation of gas during sleep.

The role of gut flora in the digestive system

The gut flora, also known as the gut microbiota or the gut microbiome, is a collection of microorganisms, predominantly bacteria, that populate the intestines. The gut flora is established at birth and gradually transitions towards a state resembling that of adults by the age of two.

The gut flora has a symbiotic relationship with the human body, performing a host of useful functions. The microorganisms aid the immune system, help metabolise dietary fibre into short-chain fatty acids, aid in the synthesis of certain B vitamins and vitamin K, and even help regulate the central nervous system. The gut flora also plays a role in the production of serotonin, which affects human behaviour, including mood and mental health.

The gut flora is also involved in the processing of dietary fibre, which leads to the production of helpful acids in the body, such as acetate, propionate, and butyrate. These acids can help with appetite and weight management, and indolepropionic acid, associated with gut flora and fibre intake, may reduce the risk of type 2 diabetes.

The gut flora also helps metabolise bile in the intestines. The liver sends bile to the small intestine to help digest fats, and bacteria and their enzymes help break down the bile acids so they can be reabsorbed and recycled by the liver.

The gut flora can be affected by various factors, including diet, environmental toxins, medications, and gastrointestinal motility. A diet high in sugar, saturated fats, and processed foods tends to increase the growth of less beneficial microbes. Environmental toxins such as antibiotics, heavy metals, and pesticides can wipe out good microbes and cause an overgrowth of pro-inflammatory microbes. Medications like antibiotics can also disrupt the balance of gut flora, and gastrointestinal issues like diarrhoea or constipation can impact the ability of the gut flora to function optimally.

An imbalance in the gut flora, known as dysbiosis, can contribute to various health conditions, including inflammatory bowel disease, infections, cardiovascular diseases, type 1 and 2 diabetes, irritable bowel syndrome, and autoimmune disorders.

To maintain a healthy gut flora, it is recommended to eat a well-rounded, nutritious diet with a variety of whole foods like whole grains, beans, vegetables, and fruits. Vegan and vegetarian diets can also be beneficial due to their high fibre content. It is also important to avoid high-fat and highly processed foods, stay hydrated, avoid smoking and alcohol consumption, manage stress, minimise antibiotic use, exercise regularly, and consider taking probiotics.

The impact of diet on flatulence

Flatulence is a natural bodily process that happens to most people 8-14 times a day. However, excessive flatulence can cause discomfort and distress. While it often occurs due to eating certain foods, it can be a sign of a more serious condition.

Causes of flatulence

Flatulence can be caused by normal bodily processes or by a condition affecting the digestive system. There are two main causes of flatulence:

• Exogenous sources: We swallow air when we eat, drink, or swallow saliva, especially when the body produces excess saliva due to nausea or acid reflux.
• Endogenous sources: Gas arises as a by-product of the partial digestion of certain foods in the gut.

Foods that cause flatulence

Certain foods contain sugars, starches, and fibres that the body cannot fully digest. When these items pass into the large intestine, bacteria break them down, creating gas. Foods that cause flatulence tend to be those high in certain polysaccharides, particularly oligosaccharides, such as inulin. Examples of foods that can worsen flatulence include:

• Vegetables such as cabbage, onions, Brussels sprouts, broccoli, asparagus and carrots
• Fruits such as apples, blueberries, apricots, peaches, and pears
• Dairy products, especially for those with lactose intolerance
• Pulses, including beans and lentils
• Cereals, such as wheat or oats
• Yeast in baked products, such as bread
• Carbonated drinks
• Artificial sweeteners

Reducing flatulence

Lifestyle and dietary changes can often lessen flatulence. Some suggestions to reduce flatulence include:

• Eating smaller meals more often
• Eating slowly and chewing food thoroughly
• Avoiding gum and carbonated drinks
• Not smoking
• Exercising regularly
• Drinking peppermint tea
• Choosing low-lactose dairy products
• Choosing beans that are fermented before cooking
• Taking probiotics
• Taking over-the-counter medications, such as antacids, probiotics, or lactase supplements

How to reduce flatulence

Passing gas is a normal part of the human digestive system. However, if you are experiencing excessive flatulence, there are several steps you can take to reduce it.

Firstly, it is important to note that the air you swallow throughout the day while eating, drinking, and engaging in activities like chewing gum or smoking, can contribute to flatulence. Therefore, eating and drinking slowly, avoiding gum, and cutting down on smoking can help reduce the amount of air swallowed.

Secondly, certain foods and drinks are known to increase gas production. These include carbonated beverages, fruits like apples and blueberries, vegetables like asparagus and cabbage, dairy products, beans, and foods containing artificial sweeteners. While these foods are often nutritious, reducing their consumption, especially in the evenings, can help cut down on gas.

Thirdly, regular physical activity and staying hydrated can aid in improving digestion and reducing constipation, which is a common cause of excessive flatulence.

Additionally, for those with lactose intolerance or other food intolerances, enzyme supplements like lactase enzyme supplements or over-the-counter products like Beano can aid in breaking down lactose and complex carbohydrates, reducing gas production.

Finally, if excessive flatulence persists, it is recommended to consult a healthcare professional to rule out any underlying medical conditions and discuss further treatment options.

Frequently asked questions