A new study found that people who work night shifts have much higher rates of stomach problems like irritable bowel syndrome and indigestion compared to people who work regular hours. Researchers surveyed nearly 400 night shift workers in Australia and the UK and discovered that about 1 in 5 had irritable bowel syndrome, and about 1 in 3 had functional dyspepsia (chronic indigestion). These conditions affected their quality of life and mental health, with some workers even considering changing jobs because of their symptoms. The study suggests that working against your body’s natural sleep-wake cycle may be making digestive problems worse.

The Quick Take

  • What they studied: Whether night shift workers experience more stomach and digestion problems than the general population, and how these problems affect their daily lives
  • Who participated: 392 night shift workers from Australia and the UK (about 70% women, average age 48 years) who worked at least 8 night shifts per month between 11pm and 3am
  • Key finding: More than half of night shift workers (51.7%) had either irritable bowel syndrome or functional dyspepsia, compared to much lower rates in the general population. About 60% said night shifts made their stomach problems worse.
  • What it means for you: If you work night shifts and have stomach problems, you’re not alone—your work schedule may be contributing to your symptoms. Talk to your doctor about strategies to manage your digestive health while working nights. However, this study shows a connection, not proof that night shifts cause these problems.

The Research Details

This was a cross-sectional study, which means researchers collected information from night shift workers at one point in time (March to July 2024) rather than following them over months or years. Participants completed detailed questionnaires about their stomach symptoms, using standard medical criteria to diagnose irritable bowel syndrome and functional dyspepsia. They also answered questions about their quality of life, mental health (depression and anxiety), and eating habits.

The researchers used validated tools—meaning these questionnaires have been tested and proven reliable by other scientists. This approach allowed them to gather information from a large group of people relatively quickly and affordably, making it useful for understanding how common these problems are in night shift workers.

This study design is appropriate because it provides a clear snapshot of how common stomach problems are among night shift workers right now. While it can’t prove that night shifts cause these problems, it shows a strong connection that suggests night shift work deserves more attention as a risk factor. The use of standardized medical criteria means the results are comparable to other research and reliable.

The study used validated questionnaires recognized by gastroenterologists worldwide, which strengthens the reliability of the findings. The large sample size (392 people) and inclusion of workers from two countries (Australia and UK) makes the results more generalizable. However, because this is a snapshot study rather than a long-term follow-up, we can’t determine cause-and-effect. The study also relied on self-reported information, which could be affected by memory or perception bias.

What the Results Show

Among the 392 night shift workers studied, 21.3% met the medical criteria for irritable bowel syndrome (IBS), 30.4% met criteria for functional dyspepsia (FD), and 24.5% had both conditions. These rates are substantially higher than what’s typically seen in the general population. Women were significantly more likely to have these conditions than men.

Participants with IBS and/or FD reported much worse symptoms and quality of life compared to those without these conditions. They had higher pain sensitivity, more severe digestive symptoms, and greater anxiety and depression. Notably, 59.9% of all participants said night shifts negatively affected their stomach symptoms, and 16.3% said they’d considered changing jobs because of their digestive problems.

Medication use was also higher in workers with IBS or FD (41% versus 17% in those without these conditions). This suggests people with these conditions are seeking treatment to manage their symptoms.

The study found that mental health was significantly affected in workers with stomach problems. Those with IBS and/or FD had higher scores on depression, anxiety, and stress scales. Interestingly, dietary patterns (what people ate) didn’t differ significantly between those with and without stomach problems, suggesting that food choices alone don’t explain the higher rates of these conditions in night shift workers.

The prevalence rates found in this study (21.3% for IBS and 30.4% for FD) are notably higher than reported rates in the general population, which typically range from 10-15% for IBS and 7-10% for FD. This suggests night shift work is associated with increased risk. Previous research has shown that disrupted sleep and circadian rhythms (your body’s natural 24-hour cycle) can affect digestion, and this study provides real-world evidence of that connection.

This study shows a connection between night shift work and stomach problems but cannot prove that night shifts cause these problems—other factors could be involved. The study relied on people’s own reports of symptoms rather than medical exams, which could introduce bias. The sample was 70% female, so results may not apply equally to male night shift workers. Additionally, the study didn’t include a comparison group of day workers, making it harder to determine how much higher the rates truly are. Finally, because this is a snapshot in time, we don’t know if these problems developed because of night shift work or if people with existing problems were more likely to report them.

The Bottom Line

If you work night shifts and experience stomach problems, discuss them with your doctor. Consider strategies like eating smaller, more frequent meals, avoiding heavy foods before sleep, maintaining consistent meal times despite your schedule, and managing stress. The evidence suggests that addressing sleep quality and circadian rhythm disruption may help, though more research is needed on specific interventions. (Moderate confidence—based on observational data showing association)

Night shift workers experiencing stomach problems should pay attention to these findings. Healthcare providers caring for night shift workers should screen for IBS and functional dyspepsia. Employers should consider the health impacts of night shift schedules. People without stomach problems who work night shifts may want to monitor for symptoms. This research is less relevant to day workers unless they’re considering shift work.

Improvements in digestive symptoms typically take 4-8 weeks to become noticeable when making lifestyle changes, though this varies by individual. Mental health improvements may take longer. If you’re considering job changes, discuss realistic timelines with your healthcare provider.

Want to Apply This Research?

  • Log your shift schedule (noting when you work 11pm-3am), stomach symptoms (pain, bloating, bowel changes), and mood/stress levels daily. Rate symptom severity on a scale of 1-10. Track this for 4 weeks to identify patterns between your work schedule and symptoms.
  • Set meal reminders for consistent eating times despite shift work. Use the app to plan and log smaller, lighter meals during night shifts. Track which foods seem to trigger symptoms and which don’t. Monitor sleep quality and set sleep goals even on shift days.
  • Review your symptom patterns weekly to identify triggers. Compare weeks with more night shifts to weeks with fewer shifts. Share this data with your doctor to help guide treatment decisions. Reassess every 4-8 weeks to track whether interventions are helping.

This research shows an association between night shift work and stomach problems but does not prove that night shifts cause these conditions. If you experience persistent stomach symptoms, consult with a healthcare provider for proper diagnosis and treatment. This information is for educational purposes and should not replace professional medical advice. Individual results may vary, and what works for one person may not work for another. Always discuss any significant lifestyle changes or new symptoms with your doctor.