Diarrhea at Night – Causes of Repeated Nighttime Loose Stool

Diarrhea is usually not time-specific in that it does not typically occur at some times of the day and not at others. However, some people may find that diarrheal stool is more likely to occur with eating certain foods or specific activities which may then cause the diarrhea to occur at those times. Diarrhea at night should be investigated for all the possible causes of diarrhea, irrespective of the fact that it is occurring more frequently at nighttime.

What is nocturnal diarrhea?

Nocturnal diarrhea refers to loose, watery and frequent stool that occurs at night. This is a feature that is present in a few gastrointestinal illnesses but is more often caused by diet, lifestyle, medication and psychological factors. Nocturnal diarrhea may affect sleep patterns when a person has to awaken from sleep in order to have a bowel movement. This disturbed sleep can sometimes aggravate diarrhea, especially in conditions like irritable bowel syndrome (IBS).

Of the different types of diarrhea (osmotic, secretory, exudative), nocturnal diarrhea is more often seen with secretory diarrhea. Normally water is pumped into the small intestine to facilitate digestion and absorption of nutrients. This water is later reabsorbed in the colon. However, in secretory diarrhea there is excessive pumping of water into the intestines which cannot be reabsorbed sufficiently to form soft solid stool.

Bacterial toxins, laxatives, hormones, certain drugs and toxins are the main causes of secretory diarrhea. Therefore these factors should also be considered as possible causes of nighttime diarrhea. Irrespective of the type of diarrhea or causes, it is important to seek medical attention for severe and/or persistent diarrhea. The main complication from diarrhea is dehydration which can be serious and even life-threatening if left untreated.

Causes of Nighttime Diarrhea

Several causes of nocturnal diarrhea have been discussed below but it is important to note that diarrhea with these causes does not only occur at night of during sleep. Diarrhea may arise at anytime, either during the day or at night, while awake or when asleep. Therefore all causes of chronic diarrhea, whether persistent or recurrent, needs to be considered as a possible factor in nocturnal diarrhea.

Read more on chronic diarrhea.

Irritable Bowel Syndrome (IBS)

Irritable bowel syndrome or IBS is a common cause of nocturnal diarrhea. It is not due to any clearly identifiable disease mechanism and appears to be due to a disordered bowel motility – either too fast or too slow. Although the exact cause of IBS is not known, it is known to be triggered and exacerbated by psychological factors. This may in part explain the reason for diarrhea at night in IBS. However, the diarrhea can occur anytime of the day or night.

Microscopic Colitis

Colitis is inflammation of the colon and this may occur for various reasons. Microscopic colitis is one type of colitis. The exact cause of microscopic colitis is not known but there appears to be a number of possible causative factors. This includes viruses, bacterial toxins, medication, bile acids and possibly immune-related conditionssuch as rheumatoid arthritis, celiac disease and inflammatory bowel disease (IBD).

Psychological Factors

Psychological factors may contribute to diarrhea in the backdrop of certain conditions like irritable bowel syndrome (IBS) and sometimes psychological stress on its own can hasten bowel motility and lead to diarrhea. If there are specific stressors at night or with nightmares when asleep, then diarrhea may occur or be aggravated. Sleep disorders may also contribute to diarrhea for various reasons, one of which is the stress that sleeplessness may cause.

Foods and Drinks Before Bedtime

One of the more common causes of nighttime diarrhea is related to dietary factors. Foods and beverages that are consumed a short while before bedtime (such as with dinner, bedtime snacks and night caps) may be the reasons for diarrhea at night.

Even without food poisoning or gastroenteritis, some foods and beverages can irritate the bowel lining, disturb digestion and absorption and impede stool formation. All of this may lead to diarrhea. One such instances is with dairy which can lead to diarrhea within hours after being consumed in people who are lactose intolerant.


Some medication may be taken with dinner or at bedtime even if it is not needed specifically for sleep (as is the case with sedatives). Depending on the type of drug and individual sensitivity, it can lead to diarrhea usually as a side effect. This diarrhea may only occur hours after the drug is consumed and this may happen during sleep.

Another effect that may be related to medication is when diarrheal conditions are being treated. The drug used in treating these conditions may wear off during the course of the night. As a result diarrhea and other symptoms of these conditions may arise while a person is asleep.

Read more on morning diarrhea.

Treatment for Nocturnal Diarrhea

The treatment for diarrhea at night depends on the underlying cause. In some cases where these conditions are already being treated and managed, a change in prescription may be necessary to ensure that the effects of the drug do no wear off when asleep. Similarly drugs that may cause diarrhea at night as a side effect may have to be changed or discontinued. However, a change or discontinuation of any prescription should not be done unless advised by a medical doctor.

Antidiarrheals are usually not the first choice of treatment for diarrhea. It may be prescribed if the underlying cause of nocturnal diarrhea is being treated by the diarrhea persists. In these case antidiarrheals can provide symptomatic relief for a short period of time and allows a person to sleep without being disturbed by a bowel movement. In addition these antidiarrheal drugs can be discontinued once the underlying condition has resolved or is under control as part of long term management.

Diet and Lifestyle for Nocturnal Diarrhea

Some of the dietary and lifestyle factors that may be helpful for nocturnal diarrhea may include:

  • Avoid eating, whether small or large meals, for at least 2 to 3 hours before bedtime.
  • Attempt to have a bowel movement before bedtime and train the bowels to empty at this time.
  • Limit spicy, greasy and heavy meals for dinner and minimize the intake of possible triggers like alcoholic or caffeinated beverages.
  • Opt to exercise in the morning or during the day if late night workouts seem to correlate with nighttime diarrhea.

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