Sometimes a morning dump is just…weirdly satisfying. You know what we mean. It’s not just us—your biology is set up for it to happen, thanks to how your muscles and nerves work. Here’s what’s going on:

It’s a relief for your muscles

Ever since last night’s dinner was digested, whether that was kale and kombucha or whiskey and filet mignon, your colon has been gradually expanding to accommodate the byproducts. Stretch receptors from your gut send a message to your brain that it’s time to get rid of what’s been building up.

Meanwhile, certain parts of your body are contracting to hold it in—specifically, your two anal sphincters (an internal one that’s an automatic muscle that requires no thought (whew), and an external, voluntary one). The rest of the muscles in the gut also contract both forward to move things through, and backwards so that water and nutrients can be absorbed. All this contracting leads to increased abdominal pressure (you know the feeling). Most of what we feel normally is the expansion of the bowels with air or fluid or poop.

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And when that pressure builds up, your stretch receptors send “get this out of here” signals to your brain. When you finally do go, abdominal pressure decreases and stretch receptors relax. The release of all that tension naturally feels great. (Although in some folks, this abdominal pressure may not go away; this could be the result of gut bacteria that produces gases, or it could be due to your diet, or the presence of specific intestinal enzymes.)

Your nerves love a good dump, too

There are a huge number of nerve endings where your waste products pass: the anus has among the most in your entire body. It's the only organ that senses and differentiates gas from liquid from solids (poop). Nerves there, just like nerves anywhere else, transmit sensations like temperature, pain, and pleasure to your brain.

Two nerves in particular may be key factors in the feel-good experience.

The vagus nerve sends pleasant signals to your brain. Body functions that keep your body relaxed, like breathing and digestion, are largely driven by the vagus nerve, one of the biggest nerves in the human body that controls most of the gut. As you poop, this nerve transmits the satisfying sensation of decreased abdominal pressure. Your brain often perceives these nerve signals to be pleasurable as it is associated with completion of a task (that would be pooping). Stimulation of the vagus nerve through defecation could even momentarily lower heart rate and blood pressure.

sends pleasant signals to your brain. Body functions that keep your body relaxed, like breathing and digestion, are largely driven by the vagus nerve, one of the biggest nerves in the human body that controls most of the gut. As you poop, this nerve transmits the satisfying sensation of decreased abdominal pressure. Your brain often perceives these nerve signals to be pleasurable as it is associated with completion of a task (that would be pooping). Stimulation of the vagus nerve through defecation could even momentarily lower heart rate and blood pressure. The pudendal nerve might get in the act, too. This nerve also provides sensory information from your anus to your brain—and it happens to be one that’s also in the clitoris and penis. Although this hasn’t been studied formally, some scientists suggest that the pudendal nerve could contribute to enjoyable dumps, since it often carries the feeling of pleasure.

Although not fully studied, guys may even have a satisfaction advantage: For men, the prostate could even be involved. Often considered the male G-spot, this gland, situated just in front of the rectum, may be stimulated by particularly large bowel movements.

If you don’t tend to poop on a regular schedule but feel perfectly okay, that's generally fine. If you don’t feel completely satisfied after your poop and feel you can go again, here’s how to get your gut into a better routine.

Chethan Ramprasad. M.D. is an internal medicine resident physician at NYU Langone.

Baha Moshiree M.D., is a gastroenterologist and internist and director of the Motility Program at the University of North Carolina in Charlotte, NC. She also works with the International Foundation for GI disorders patient advocacy groups.

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