Mon Jun 17

Why do I poo in the morning? A gut expert explains

Written by Vincent Ho, Associate Professor and clinical academic gastroenterologist, Western Sydney University

No, you’re not imagining it. People really are more likely to poo in the morning, shortly after breakfast. Researchers have actually studied this.

But why mornings? What if you tend to poo later in the day? And is it worth training yourself to be a morning pooper?

To understand what makes us poo when we do, we need to consider a range of factors including our body clock, gut muscles and what we have for breakfast.

Here’s what the science says.

So morning poos are real?

In a UK study ^[1] from the early 1990s, researchers asked nearly 2,000 men and women in Bristol about their bowel habits.

The most common time to poo was in the early morning ^[2]. The peak time was 7-8am for men and about an hour later for women. The researchers speculated that the earlier time for men was because they woke up earlier for work.

About a decade later, a Chinese study ^[3] found a similar pattern. Some 77% of the almost 2,500 participants said they did a poo in the morning.

But why the morning?

There are a few reasons. The first involves our circadian rhythm ^[4] – our 24-hour internal clock that helps regulate bodily processes, such as digestion.

For healthy people, our internal clock means the muscular contractions in our colon follow a distinct rhythm ^[5].

There’s minimal activity in the night. The deeper and more restful our sleep, the fewer ^[6] of these muscle contractions we have. It’s one reason why we don’t tend to poo in our sleep.

Diagram of digestive system including colon and rectum

Your lower gut is a muscular tube that contracts more strongly at certain times of day. Vectomart/Shutterstock ^[7]

But there’s increasing activity during the day. Contractions in our colon are most active in the morning after waking up and after any meal.

One particular type of colon contraction partly controlled by our internal clock are known as “mass movements ^[8]”. These are powerful contractions that push poo down to the rectum to prepare for the poo to be expelled from the body, but don’t always result in a bowel movement. In healthy people, these contractions occur a few times a day. They are more frequent in the morning than in the evening, and after meals.

Breakfast is also a trigger for us to poo. When we eat and drink our stomach stretches, which triggers the “gastrocolic reflex ^[9]”. This reflex stimulates the colon to forcefully contract and can lead you to push existing poo in the colon out of the body. We know the gastrocolic reflex is strongest in the morning. So that explains why breakfast can be such a powerful trigger for a bowel motion.

Then there’s our morning coffee. This is a very powerful stimulant ^[10] of contractions in the sigmoid colon (the last part of the colon before the rectum) and of the rectum itself. This leads to a bowel motion.

How important are morning poos?

Large international ^[11] surveys ^[12] show the vast majority of people will poo between three times a day and three times a week.

This still leaves a lot of people who don’t have regular bowel habits, are regular but poo at different frequencies, or who don’t always poo in the morning.

So if you’re healthy, it’s much more important that your bowel habits are comfortable and regular for you. Bowel motions do not have to occur once a day in the morning.

Morning poos are also not a good thing for everyone. Some people ^[13] with irritable bowel syndrome ^[14] feel the urgent need to poo in the morning – often several times after getting up, during and after breakfast. This can be quite distressing. It appears this early-morning rush to poo is due to overstimulation of colon contractions in the morning.

Can you train yourself to be regular?

Yes, for example, to help treat constipation using the gastrocolic reflex. Children and elderly people with constipation can use the toilet immediately after eating breakfast to relieve symptoms ^[15]. And for adults with constipation, drinking coffee regularly can help stimulate the gut, particularly in the morning.

A disturbed circadian rhythm can also lead to irregular bowel motions and people more likely to poo in the evenings ^[16]. So better sleep habits can not only help people get a better night’s sleep, it can help them get into a more regular bowel routine.

Man preparing Italian style coffee at home, adding coffee to pot

A regular morning coffee can help relieve constipation. Caterina Trimarchi/Shutterstock ^[17]

Regular physical activity and avoiding sitting down a lot ^[18] are also important in stimulating bowel movements ^[19], particularly in people with constipation.

We know stress ^[20] can contribute to irregular bowel habits. So minimising stress and focusing on relaxation can help ^[21] bowel habits become more regular.

Fibre from fruits and vegetables also helps ^[22] make bowel motions more regular.

Finally, ensuring adequate hydration ^[23] helps minimise the chance of developing constipation, and helps make bowel motions more regular.

Monitoring your bowel habits

Most of us consider pooing in the morning to be regular. But there’s a wide variation in normal so don’t be concerned if your poos don’t follow this pattern. It’s more important your poos are comfortable and regular for you.

If there’s a major change in the regularity of your bowel habits that’s concerning you, see your GP. The reason might be as simple as a change in diet or starting a new medication.

But sometimes this can signify an important change in the health of your gut. So your GP may need to arrange further investigations, which could include blood tests or imaging.