Hemorrhoids affect approximately half of all adults by age 50, and the standard list of risk factors, constipation, low fiber intake, straining, and prolonged sitting, has not changed in decades. But a 2026 study published in Neuropsychiatric Research has added a surprising entry to that list: poor sleep. Researchers at Peking University People’s Hospital used a genetic analysis technique called Mendelian randomization to examine data from more than 218,000 hemorrhoid cases and over 725,000 controls and found that insomnia, long sleep duration, and daytime napping each independently increased the odds of developing hemorrhoids. The genetic design confirmed the direction of causation: disrupted sleep contributes to hemorrhoid risk, not the reverse. This article covers the study, the biological mechanisms that may explain the connection, and the evidence-based prevention strategies that now include sleep alongside fiber, hydration, and bowel habits.
The Study That Surprised Gastroenterologists
Hemorrhoids have been studied for centuries, and the risk factor profile has remained remarkably stable: constipation, straining during bowel movements, low fiber intake, prolonged sitting on the toilet, pregnancy, and aging. Sleep was never on the list.
A 2026 study published in Neuropsychiatric Research by researchers at Peking University People’s Hospital in Beijing changed that. The team used Mendelian randomization, a technique that uses naturally occurring genetic differences between people to investigate cause and effect, analyzing genetic data from over 218,000 hemorrhoid cases and more than 725,000 controls drawn from the UK Biobank and FinnGen databases.
The study examined seven sleep-related traits: insomnia, sleep duration, short sleep, long sleep, daytime napping, chronotype (being a morning or evening person), and daytime sleepiness.
Three traits emerged as independent risk factors for hemorrhoid disease: insomnia, long sleep duration, and daytime napping.
The Mendelian randomization design is what gives this finding its weight. Traditional observational studies can show that two things occur together but cannot determine which causes which, or whether both are caused by something else entirely. Mendelian randomization uses genetic variants as natural proxies for exposures (in this case, sleep traits), which are randomly assigned at conception and are therefore less susceptible to the confounding factors that plague conventional studies.
The analysis confirmed the direction of causation: sleep problems contribute to hemorrhoids, not the other way around.
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Why Sleep and Hemorrhoids Might Be Connected
At first glance, the idea that how you sleep could affect your rectal veins seems implausible. But the biological pathways connecting the two are more direct than they appear.
Disrupted Gut Motility and Constipation
Sleep plays a central role in regulating the enteric nervous system, the network of neurons that controls gut motility (the muscular contractions that move food and waste through the digestive tract). Insomnia and fragmented sleep disrupt the normal rhythmic contractions of the colon, particularly the “mass movements” that typically occur in the morning after waking.
The result: slower transit time, harder stools, and constipation. Constipation is the single most well-established risk factor for hemorrhoids. A 2015 cross-sectional study of 2,813 participants published in PLOS One found that constipation increased hemorrhoid prevalence by 43% (OR 1.43, 95% CI 1.11 to 1.86) (Peery et al., 2015).
When stool is hard and passage is difficult, people strain. Straining increases pressure on the veins in the rectal and anal cushions, and over time, that repeated pressure causes those veins to swell, distend, and bleed.
Systemic Inflammation
Poor sleep disrupts digestion and causes inflammation, both tied to hemorrhoid development.
Sleep deprivation elevates inflammatory markers including C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha). Chronic low-grade inflammation weakens the connective tissue and vascular structures in the anal cushions, making them more susceptible to prolapse and swelling.
Autonomic Nervous System Imbalance
Insomnia and poor sleep quality shift the autonomic nervous system toward sympathetic dominance (the fight-or-flight state). This affects vascular tone throughout the body, including in the hemorrhoidal venous plexus. Prolonged sympathetic activation can alter blood flow patterns in ways that promote venous congestion in the pelvic region.
Cortisol and Vascular Effects
Sleep disruption elevates cortisol, the body’s primary stress hormone. Chronically elevated cortisol weakens blood vessel walls, impairs tissue repair, and promotes fluid retention, all of which can contribute to the swelling and fragility of hemorrhoidal tissue.
Behavioral Changes
People who sleep poorly tend to be more sedentary during the day. They are also more likely to have irregular bowel habits, make poorer dietary choices (higher sugar, lower fiber), and spend more time sitting, including on the toilet. Each of these behavioral consequences of poor sleep is itself an independent hemorrhoid risk factor.
The 2026 Columbia University sleep study (covered in a previous article on this site) confirmed that sleep-deprived individuals became more sedentary by an average of 17 minutes per day, with men and postmenopausal women increasing by nearly 30 minutes (Zuraikat et al., 2026).
What Mendelian Randomization Can and Cannot Tell Us
Mendelian randomization is a powerful tool for investigating causal relationships using genetic data, but it is not a clinical trial.
What it can do:
- Use genetic variants as natural “instruments” for exposure (in this case, genetic predisposition to insomnia, long sleep, or napping)
- Establish the direction of causation (does A cause B, or does B cause A?)
- Reduce confounding bias because genetic variants are assigned at conception, before lifestyle factors take effect
What it cannot do:
- Quantify exactly how much improving your sleep will reduce your hemorrhoid risk (the effect size is not directly translatable to individual clinical advice)
- Account for all possible genetic interactions (a limitation called pleiotropy)
- Replace a randomized controlled trial, which remains the gold standard for causal evidence
The researchers themselves note that Mendelian randomization “remains a genetic method with its own assumptions rather than an actual clinical trial.”
The finding should be interpreted as strong genetic evidence supporting a causal relationship between certain sleep traits and hemorrhoid risk, not as a proven clinical intervention. No study has yet tested whether improving sleep directly reduces hemorrhoid incidence.
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The Standard Risk Factors: What We Already Knew
The sleep connection adds to, rather than replaces, the established risk factor profile for hemorrhoids.
Constipation and Straining
Straining during bowel movements is the most direct mechanical cause of hemorrhoid development. Hard, infrequent stools require more force to pass, which increases pressure on the hemorrhoidal venous cushions. Over time, this pressure causes the cushions to stretch, swell, and potentially prolapse.
Low Fiber Intake
A review of anorectal disorders concluded that fiber supplementation can reduce hemorrhoidal symptoms by up to 50%.
A 2026 cross-sectional study published in Frontiers in Public Health found a dose-response relationship between dietary fiber intake and hemorrhoid risk among sedentary professionals: at low fiber intake levels, even modest increases in dietary fiber may improve stool bulk, stool consistency, and bowel movement frequency, thereby reducing constipation-related straining.
The recommended daily fiber intake for hemorrhoid prevention is 25 to 35 grams from fruits, vegetables, whole grains, and legumes.
Prolonged Toilet Sitting
Sitting on the toilet for extended periods, often while scrolling a phone, allows gravity and the position of the body to increase pressure on the pelvic floor veins. Clinical guidelines recommend limiting toilet time to five minutes or less.
Dehydration
Inadequate hydration was directly correlated with hemorrhoidal symptom severity and bleeding in patients. Water keeps stools soft and maximizes the effectiveness of dietary fiber. Without adequate hydration, fiber can actually harden stool rather than soften it.
Sedentary Lifestyle
Prolonged sitting reduces blood circulation to the pelvic region and increases venous pressure. Regular movement throughout the day, even brief walking breaks, improves pelvic blood flow.
Pregnancy
The weight of the uterus during pregnancy increases pressure on the pelvic veins. Hormonal changes also soften the walls of blood vessels, making them more susceptible to swelling.
Aging
The connective tissue supporting the hemorrhoidal cushions weakens with age, making hemorrhoids more common after 50.
The Updated Prevention Strategy
Based on the established evidence and the new sleep data, the most comprehensive hemorrhoid prevention plan now includes seven components:
1. Eat 25 to 35 Grams of Fiber Daily
The highest-impact dietary change for hemorrhoid prevention. Good sources include beans, lentils, raspberries, oats, whole wheat bread, broccoli, chia seeds, and pears. Increase fiber gradually over two to three weeks to avoid bloating and gas.
2. Drink Enough Water
Aim for at least 8 cups (64 ounces) of water daily, and more if you exercise, live in a hot climate, or are increasing your fiber intake. Adequate hydration keeps stools soft and easy to pass.
3. Do Not Sit on the Toilet Longer Than Five Minutes
If a bowel movement does not happen within five minutes, stand up and try again later. Prolonged sitting on the toilet is one of the most common and most correctable risk factors. Leave your phone outside the bathroom.
4. Do Not Strain
If you need to strain, your stool is too hard, your timing is off, or both. Adding fiber and water typically resolves the problem. A small footstool (such as a Squatty Potty) elevates the knees above the hips and straightens the anorectal angle, making passage easier without straining.
5. Move Throughout the Day
If you work at a desk, stand and walk for two to three minutes every hour. Regular exercise (150 minutes of moderate activity per week) improves overall circulation, including in the pelvic region.
6. Improve Your Sleep (the New Addition)
Based on the 2026 Peking University study, addressing sleep quality joins the prevention list. Specifically:
- If you have insomnia: Establish a consistent sleep-wake schedule, limit caffeine after noon, keep the bedroom cool and dark, avoid screens for 30 minutes before bed, and consult a doctor if insomnia persists beyond four weeks
- If you sleep too long (more than 9 hours regularly): Excess sleep is associated with poor sleep quality, depression, and metabolic disruption. Aim for 7 to 8 hours of actual sleep
- If you nap excessively during the day: Frequent daytime napping may signal poor nighttime sleep quality. If you nap daily, limit naps to 20 to 30 minutes before 2 PM
7. Respond to the Urge
When you feel the urge to have a bowel movement, go. Delaying allows the stool to harden in the rectum as water is reabsorbed, making passage more difficult and increasing the need to strain.
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Myths vs. Facts About Hemorrhoids
| Myth | Fact |
|---|---|
| Hemorrhoids are caused by sitting on cold surfaces. | There is no evidence linking cold surfaces to hemorrhoid development. Constipation, straining, and prolonged toilet sitting are the established causes. |
| Only older adults get hemorrhoids. | Hemorrhoids can develop at any age. The 2026 Frontiers study found high rates among sedentary young professionals. |
| Spicy food causes hemorrhoids. | Spicy food does not cause hemorrhoids, though it can irritate existing ones and worsen symptoms. |
| Hemorrhoids are always painful. | Internal hemorrhoids are often painless. The most common symptom is painless bleeding during bowel movements. |
| Sleep has nothing to do with hemorrhoids. | The 2026 Mendelian randomization study found that insomnia, long sleep duration, and daytime napping each independently increase hemorrhoid risk through genetic causal analysis. |
| You need surgery if you get hemorrhoids. | Most hemorrhoids resolve with conservative treatment: fiber, hydration, sitz baths, and topical medications. Surgery is reserved for severe or persistent cases. |
Frequently Asked Questions
Can poor sleep really cause hemorrhoids?
A 2026 Mendelian randomization study of over 218,000 hemorrhoid cases found that insomnia, long sleep duration, and daytime napping each independently increase hemorrhoid risk. The genetic design confirmed that sleep problems contribute to hemorrhoids, not the reverse. The likely mechanisms include disrupted gut motility, systemic inflammation, and behavioral changes associated with poor sleep.
How common are hemorrhoids?
Hemorrhoids affect approximately 50% of adults by age 50. A 2026 systematic review in Annals of Medicine provided updated worldwide prevalence data confirming that hemorrhoids remain one of the most common conditions in gastroenterology.
What is the best way to prevent hemorrhoids?
The most effective prevention strategy includes eating 25 to 35 grams of fiber daily, drinking adequate water, limiting toilet time to five minutes, avoiding straining, exercising regularly, improving sleep quality, and responding promptly to the urge to have a bowel movement.
Does fiber really help prevent hemorrhoids?
Yes. A review of anorectal disorders found that fiber supplementation reduces hemorrhoidal symptoms by up to 50%. A 2026 dose-response study confirmed that even modest increases in fiber intake significantly reduce hemorrhoid risk among sedentary workers.
What sleep habits are linked to hemorrhoids?
The 2026 Peking University study identified three: insomnia, habitually long sleep (more than 9 hours), and frequent daytime napping. All three were independently associated with increased hemorrhoid risk in the genetic analysis.
When should I see a doctor about hemorrhoids?
See a doctor if you notice rectal bleeding (to rule out other causes), if hemorrhoid symptoms persist despite two weeks of home treatment, if you experience severe pain, if a lump protrudes from the anus and cannot be pushed back in, or if you are over 45 and have never been screened for colorectal cancer.
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Expert Tips
- Start with fiber and water before anything else. These two changes address constipation, the single biggest modifiable risk factor for hemorrhoids. If you do nothing else, adding a daily serving of beans or oats and drinking one extra glass of water will reduce your risk.
- Leave your phone outside the bathroom. The average person spends 10 to 15 minutes on the toilet when they have a phone. Without it, most bowel movements take three to five minutes. That difference directly affects pelvic vein pressure.
- Take the sleep connection seriously. The Mendelian randomization evidence is new but robust. If you have chronic insomnia and recurring hemorrhoids, treating the insomnia may help break the cycle.
- Do not ignore rectal bleeding. Hemorrhoids are the most common cause of rectal bleeding, but they are not the only cause. Colorectal cancer, inflammatory bowel disease, and anal fissures can all produce similar symptoms. Any new rectal bleeding warrants evaluation.
- Use a footstool. Elevating your feet on a small stool during bowel movements straightens the anorectal angle and reduces the need to strain. It is one of the simplest, cheapest, and most effective hemorrhoid prevention tools.
Key Takeaways
- A 2026 Mendelian randomization study published in Neuropsychiatric Research analyzed genetic data from over 218,000 hemorrhoid cases and found that insomnia, long sleep duration, and daytime napping each independently increase hemorrhoid risk.
- The genetic design confirmed causation runs from sleep to hemorrhoids, not the reverse.
- The likely biological mechanisms include disrupted gut motility leading to constipation, systemic inflammation weakening vascular tissue, autonomic nervous system imbalance, elevated cortisol, and behavioral changes (more sedentary time, poorer diet).
- Sleep joins the established list of hemorrhoid risk factors: constipation, straining, low fiber intake, prolonged toilet sitting, dehydration, sedentary lifestyle, pregnancy, and aging.
- The most effective prevention strategy now includes seven components: adequate fiber (25 to 35g daily), sufficient hydration, limited toilet time, no straining, regular movement, improved sleep quality, and prompt response to bowel urges.
- Hemorrhoids affect approximately 50% of adults by age 50. Most cases respond to conservative treatment without surgery.
A Risk Factor Nobody Saw Coming
When researchers at Peking University set out to study the genetic relationship between sleep and hemorrhoids, they were testing a hypothesis that most clinicians would have dismissed. Hemorrhoids are a mechanical problem, the thinking went, caused by pressure, straining, and gravity. What could sleep possibly have to do with it?
The answer, backed by genetic data from nearly a million people, is: more than anyone expected. Insomnia disrupts the gut’s motility. Inflammation weakens the tissue that holds hemorrhoidal cushions in place. Poor sleep makes people more sedentary, more constipated, and less likely to eat the fiber that keeps their stools soft.
None of this means that getting a good night’s sleep will cure your hemorrhoids. But it does mean that chronic poor sleep may be quietly contributing to a condition that millions of people treat with creams and fiber supplements while ignoring the factor that runs underneath both: the quality of the hours they spend asleep.
If your hemorrhoids keep coming back despite doing everything right during the day, it may be worth looking at what is happening during the night.
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Also Read | How Sleep Deprivation Could Quietly Add 9 Pounds Per Year
References
Esmaeilnia Shirvani, A., Pakdaman, K., Maleki, Z., Soraneh, S., Rezaei Chegini, F., & Pakdaman, K. (2026). Worldwide prevalence of haemorrhoids: A systematic review and meta-analysis. Annals of Medicine, 58, 2606433. https://doi.org/10.1080/07853890.2025.2606433
Gao, J., Li, D., Liu, J., Liu, F., Wu, S., & Zhao, Y. (2026). Dose-response association between dietary fiber intake and hemorrhoid risk among sedentary professionals: A cross-sectional study. Frontiers in Public Health, 14, 1842474. https://doi.org/10.3389/fpubh.2026.1842474
Pang, C., Wang, Y., & Wang, Y. (2026). Causal relationships between sleep traits and hemorrhoidal disease: A Mendelian randomization study. Neuropsychiatric Research. Peking University People’s Hospital, Beijing, China.
Peery, A. F., Sandler, R. S., Galanko, J. A., Bresalier, R. S., Figueiredo, J. C., Ahnen, D. J., … & Baron, J. A. (2015). Risk factors for hemorrhoids on screening colonoscopy. PLOS One, 10(9), e0139100. https://doi.org/10.1371/journal.pone.0139100
Shilpa, P. N., & Shanmugaloga, S. (2025). Lifestyle modifications in anorectal disorders: A review. Journal of Ayurveda and Integrated Medical Sciences.
Zuraikat, F. M., et al. (2026). Effects of mild sleep restriction on body weight and related outcomes in adults. Annals of Internal Medicine. Columbia University.
