How Your Body Prevents You From Peeing While Asleep

The human body is a fascinating machine, and one of its many wonders is the ability to hold pee while asleep. While it may seem like a simple task, the process involves a complex coordination of muscles, nerves, and hormones. The brain and bladder work together to ensure that we don't wet the bed, but sometimes, this communication breaks down, leading to nocturnal enuresis, or bed-wetting. This condition can affect both children and adults and has several possible causes, including hormonal imbalances, bladder issues, genetics, sleep disorders, and medical conditions. Understanding the intricate interplay between the brain and bladder is crucial for addressing bed-wetting and maintaining overall urological health.

The role of the antidiuretic hormone (ADH)

The antidiuretic hormone (ADH) is a crucial regulator of the body's fluid balance, primarily by controlling the amount of water excreted by the kidneys. Also known as vasopressin or arginine vasopressin (AVP), ADH is produced by specialised nerve cells in the hypothalamus, the area at the base of the brain. Once released, it acts on the kidneys and blood vessels to maintain blood pressure, blood volume, and tissue water content.

ADH plays a vital role in reducing water loss by increasing water reabsorption in the kidneys. It does this by allowing water in the urine to be reabsorbed back into the body in a specific area of the kidney, known as the late distal tubule and collecting duct. This process increases the concentration of urine and ensures that more water returns to the bloodstream, thereby reducing water loss. Additionally, ADH causes blood vessels to constrict, leading to increased blood pressure.

The release of ADH is carefully controlled by various factors. Sensors in the body, called baroreceptors, detect changes in blood volume and blood pressure. When a decrease in blood volume or low blood pressure is detected, as in dehydration or haemorrhage, these sensors stimulate the release of ADH. Osmoreceptors in the hypothalamus also play a role by detecting increases in salt concentration in the bloodstream, such as when an individual doesn't drink enough water on a hot day. These osmoreceptors then trigger the release of ADH.

ADH levels can have significant impacts on the body. A deficiency in ADH will cause the kidneys to excrete too much water, leading to dehydration and a drop in blood pressure. On the other hand, excessively high levels of ADH will cause the kidneys to retain too much water, resulting in a condition called Syndrome of Inappropriate Anti-Diuretic Hormone secretion (SIADH). This condition is characterised by low salt concentration in the blood due to excessive water retention.

In summary, the antidiuretic hormone (ADH) is essential for maintaining the body's fluid balance. It acts on the kidneys to regulate water reabsorption, thereby controlling the amount of water excreted in urine. ADH release is influenced by various factors, including blood volume, blood pressure, and salt concentration in the bloodstream. Adequate ADH levels are crucial for maintaining health, as imbalances can lead to dehydration or conditions like SIADH.

Why people with diabetes insipidus may pee in their sleep

Typically, the body is able to prevent bedwetting by signalling the brain when the bladder is full, even while asleep. However, people with diabetes insipidus may pee in their sleep due to the condition affecting the antidiuretic hormone (ADH) or vasopressin, which is responsible for regulating the amount of urine produced.

Diabetes insipidus is a rare condition where the body produces excessive urine and is unable to properly retain water. It is caused by issues with the production or utilisation of ADH, either due to insufficient production by the hypothalamus or improper usage by the kidneys. This results in frequent urination, even at night, as the body is unable to retain urine effectively.

The condition can be further categorised into four types: central, nephrogenic, dipsogenic, and gestational diabetes insipidus. Central diabetes insipidus occurs when the body doesn't produce enough ADH, while nephrogenic diabetes insipidus happens when the kidneys don't respond appropriately to the hormone. Dipsogenic diabetes insipidus is caused by issues with the hypothalamus unrelated to ADH production, leading to increased thirst and urination. Lastly, gestational diabetes insipidus is a rare form that can develop during pregnancy due to the placenta producing an excess of an enzyme that breaks down ADH.

People with diabetes insipidus may experience symptoms such as frequent urination, both during the day and at night, passing large amounts of light-coloured urine, and constant thirst. They may also drink large amounts of water due to constant thirst, which can further contribute to nighttime urination.

It is important to note that diabetes insipidus is distinct from diabetes mellitus, which is associated with high blood sugar levels and improper insulin usage. While both conditions can lead to increased thirst and urination, their underlying causes and treatments differ.

How bladder control develops as we age

Bladder control is something that develops as we age. For babies and young children, the bladder has reflexes, meaning it automatically knows when to squeeze the muscles to empty urine. This is why babies typically wear diapers. As children grow, the bladder muscles and nerves also grow, giving them more control over their bladder. By the age of 3 or 4, children in the US are usually toilet trained and can voluntarily use the toilet. They can feel when their bladder is getting full, and their brain can receive and understand that signal, telling the bladder to "hold it" until they reach a toilet.

However, bladder control can be more difficult to maintain during sleep, as the sleeping brain doesn't receive signals in the same way as when awake. While the bladder continues to fill with urine and send signals to the brain, the brain will usually tell the bladder to hold it until morning to help the body get enough sleep. Sometimes, the brain will wake the body up to empty the bladder if it's very full.

As people age, their kidneys and bladder change, which can affect their function. The amount of kidney tissue decreases, kidney function diminishes, and the bladder muscles weaken. The bladder wall changes, with the elastic tissue becoming stiffer, resulting in a reduced capacity to hold urine. These changes can lead to bladder control issues such as leakage or urinary incontinence. Urinary incontinence is more common in older people, especially women. It can be caused by various factors, including urinary tract infections, vaginal infections or irritations, constipation, weak bladder or pelvic floor muscles, and damage to nerves that control the bladder due to diseases such as multiple sclerosis, diabetes, or Parkinson's disease.

The impact of caffeine and alcohol on bedwetting

The human body is designed to prevent bedwetting, also known as nocturnal enuresis. The bladder stores urine and signals the brain when it's full, even while you're asleep. The brain then tells the bladder to hold it until you're ready to go to the bathroom. However, certain factors like caffeine and alcohol can impact this process and increase the risk of bedwetting.

Caffeine is a diuretic, which means it increases urine production. It also acts as a bladder stimulant, causing the detrusor muscle in the bladder to contract and signal the need to urinate before the bladder is full. As a result, consuming caffeinated beverages can lead to a higher frequency of urination. This is especially true when caffeine is consumed in combination with alcohol, as they often are (for example, in rum and Coke). Therefore, it is advisable to avoid caffeine before a night of drinking alcohol or if you are prone to bedwetting.

Alcohol has multiple effects on the body that can contribute to bedwetting. Firstly, it suppresses the production of the antidiuretic hormone (ADH), which normally signals the kidneys to conserve water and reduce urine production. By inhibiting ADH, alcohol leads to increased urine production, resulting in a fuller bladder. Secondly, alcohol irritates the detrusor muscle in the bladder, which is responsible for signalling the need to urinate. When inhibited by alcohol, this muscle may not function properly, making it difficult to recognize the urge to urinate, especially during sleep. Thirdly, alcohol consumption can deplete the body's liquid reserves, leading to dehydration and further increasing the volume of urine in the bladder. Additionally, the volume and timing of alcohol consumption can be factors, as drinking large quantities in the evening, closer to bedtime, gives the bladder more urine to hold throughout the night.

To prevent bedwetting, it is recommended to drink in moderation, pace your fluid intake, and be mindful of your beverage choices, opting for drinks with lower caffeine content. Emptying your bladder before bed and setting a middle-of-the-night alarm to wake up and urinate can also help.

What to do if you start wetting the bed as an adult

Bed-wetting as an adult can be an embarrassing and distressing experience. However, it's important to remember that it's not your fault and that you have lots of options to fix it. The first step is to see a doctor, who will likely refer to your problem as nocturnal enuresis, the medical name for the condition.

There are several reasons why you might start wetting the bed as an adult. Your doctor will be able to help you identify the specific cause and advise on the best treatment. Some common causes of adult bed-wetting include:

• Your kidneys make more pee than normal. This could be due to a lack of a hormone called ADH, which tells your kidneys to make less urine, especially at night.
• Your bladder can't hold enough urine, so pee leaks.
• Overactive bladder (OAB), where your bladder muscles squeeze too often or at the wrong times.
• Certain medications, such as sleeping pills or antipsychotics, can irritate your bladder.
• Conditions that affect your body's ability to store and hold urine, such as bladder or prostate cancer, or diseases of the brain and spine, such as seizure disorders, multiple sclerosis, or Parkinson's disease.
• Blocked urethra (the tube that carries urine from the bladder).
• Obstructive sleep apnea.
• Pelvic organ prolapse.
• Problems with the structure of your bladder or other urinary organs.
• Urinary tract stones or infection.

Your doctor will perform an exam and ask about your symptoms and medical history. They may also recommend some tests, such as:

• Urinalysis: Checking a urine sample for signs of infection or other conditions of the urinary tract.
• Urine culture: Sending a small urine sample to a lab to look for bacteria or yeast, which can indicate a urinary tract infection.
• Uroflowmetry: Measuring how much urine you produce and how quickly it flows.
• Post-void residual urine measurement: Measuring how much urine is left in your bladder after you pee.

Your doctor may suggest some changes to your daily and nightly routines, such as:

• Bladder retraining: Going to the bathroom at set times during the day and night, gradually increasing the time between visits to train your bladder to hold more fluid.
• Reducing fluid intake before bed and avoiding caffeine and alcohol, which can stimulate your bladder.
• Using an alarm clock to wake you up at regular intervals during the night to use the bathroom.
• Trying a bed-wetting alarm system, which attaches to your underwear or a pad on your bed and alerts you as soon as you start to wet the bed.
• Taking medication to reduce urine production or calm overactive bladder muscles.

If these treatments don't work, your doctor may recommend more invasive procedures, such as sacral nerve stimulation or detrusor myectomy, to treat an overactive bladder.

In the meantime, you can take some simple steps to manage the situation, such as using a waterproof mattress cover or pad, wearing absorbent underwear or pads to bed, and using special skin cleansing cloths and lotions to prevent skin irritation.

Frequently asked questions