What is morning diarrhea?
Morning diarrhea is a term used to describe loose, watery stool and an urgent need to have a bowel movement upon waking. In some people, the need to pass stool may disturb sleep within the early hours of the morning. Morning diarrhea is not a specific symptom that clearly indicates a definite cause. It is frequently seen in most gastrointestinal disorders where diarrhea is a feature. However, it tends to be more common in a person suffering with bowel disorders such as irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). This most likely indicates a psychosomatic element as both these disorders are aggravated with stress and anxiety.
Reasons for morning diarrhea
Normal bowel activity slows down during sleep and increases during the waking hours. This is partly due to the activity of hormones and nerves controlling the movement within the bowels (motility) which increases during the waking hours. It is also due to the fact that a person is more physically active during the waking hours and eating frequently throughout the day. These factors are the reason why bowel movements tend to occur during the day and less frequently at night. Furthermore during the sleeping state the body ‘deactivates’ many sensations and processes, such as defecation.
A person with good bowel habit and sleeping patterns may find the urge to defecate upon waking in the morning or shortly thereafter. This is not abnormal. It is usually associated with an approximate time and whether awake or asleep, the urge to pass stool may occur within this time period. However, it is not an uncontrollable urge to have a bowel movement and the stool is not loose or watery.
In morning diarrhea, there is an urgent need to defecate upon waking or shortly thereafter. It may be to the extent that a person is disturbed from sleep to have a bowel movement. This may occur for a number of reasons :
- Changes in the circadian rhythm (body clock) in the morning. According to this 24 hour cycle the bowel movements are suppressed in the late evening and a person is more likely to have a bowel movement around 8 AM. When the cycle is disrupted, certain processes may occur at uncharacteristic times.
- Hormone levels and nerve activity changes during the waking state to keep the body more active and alert. These changes may also affect normal bowel motility.
- Physical activity increases bowel motility.
- Eating upon waking (breakfast) can stimulate the defecation reflexes where food in the stomach or first part of small intestine may increase colonic motility. This is known as the gastrocolic and duodenocolic reflexes.
- Drinking coffee in the morning (caffeine) and cigarette smoking (nicotine) increases bowel activity.
- Milk or fruit juice which are common breakfast items may irritate the gut in a person who is lactose intolerant (dairy) or has fructose malabsorption (fruits).
- Stool accumulates in the colon during the night and water content within the colon may also rise leading to loose or watery morning stool.
- Bacterial activity within the bowels can increase as the contents are somewhat stagnant during sleep and new digestive enzymes which also have antibacterial actions are not reaching the lower bowels since a person is not eating.
Although the reasons above can occur in a person even without morning diarrhea and are not always indicative of a pathological cause (disease), it is more likely to be amplified in certain diseases.
Causes of Morning Diarrhea
Any cause of chronic diarrhea can be worse in the morning upon waking, following breakfast and with physical activity. However, there are certain conditions where diarrhea in the morning is more likely to occur.
Irritable bowel syndrome (IBS) is a functional bowel disorder with a change in bowel habit, abdominal pain and bloating. IBS occurs in the absence of any disease and appears to be due to faster or slower than normal bowel motility. Diarrhea-predominant IBS is where there is frequent bowel movements and loose stool. It tends to worsen with stress and with certain foods. People living with severe diarrhea-predominant IBS find that bowel movements start shortly after awakening and tends to arise after every meal.
Inflammatory bowel disease (IBD) is a chronic bowel disorder marked by inflammation of the bowel wall. There are two types – Crohn’s disease and ulcerative colitis. Diarrhea that is watery, has mucus or is bloody is a symptom of both types of inflammatory bowel disease. The diarrhea is worse at certain times and occurs as acute episodes (attacks). It does not specifically worsen in the morning during these attacks but generally the diarrhea starts from the time a person awakens. In severe cases a person may awaken from sleep, sometimes even several times, to pass stool.
Antibiotic-associated diarrhea (AAD) occurs after the use of antibiotics when the normal intestinal flora (‘good bowel bacteria’) is disturbed. Most cases resolve spontaneously within a short period of time but if it progreses to colitis (colon inflammation) it can be ongoing for long periods of time. Morning diarrhea is not a specific feature of antibiotic-associated diarrhea but it tends to arises with the stagnation of colonic contents and irritation of the bowel wall during sleep.
Substance misuse, particularly nicotine and alcohol, are known to cause bowel irritation. These substances are often used in excess during night time binges at social events. Diarrhea in the morning or upon waking is therefore a common feature the day after such a binge. It tends to occur as an isolated incident unless the behavior is repeated on an ongoing basis. Other substances including illicit drugs may also be responsible for morning diarrhea if misused the night before.
Pregnancy leads to high levels of certain hormones like estrogen and human chorionic gonadotropin (HCG). Morning sickness is associated with the elevation of these hormones and it is believed that diarrhea in pregnancy may also arise for the same reasons. Although nausea and vomiting is not always isolated to the morning and first trimester, it tends to be worse during these periods. Similarly, diarrhea associated with pregnancy can be worse in the morning particularly within the first trimester. Certain oral contraceptives may have a similar effect.
Psychosocial stress can cause diarrhea. The bowel movements may ease when a person is asleep and relaxed and worsens when awake and with any intense emotion. The diarrhea tends to ease once the stressful situation resolves or is removed.
Treatment of Morning Diarrhea
Morning diarrhea is a symptom and the cause needs to be identified before treatment can be commenced. Although these is no specific treatment for morning diarrhea itself, certain measures may be helpful in most causes. This includes :
- Probiotics to restore the normal intestinal flora.
- Avoid irritant foods and drinks which usually includes dairy, spicy foods, sweeteners, fruit juices, caffeinated beverages (large quantities) and alcohol.
- Moderate fiber intake as it can aggravate pre-existing diarrhea.
- Antidiarrheal medication like loperamide is useful for short periods of time but ultimately the cause of the diarrhea needs to be treated.