Study Reveals Impact of Stress and Nighttime Eating on Gut Health

A recent study revealed that elevated stress levels and late-night eating deliver a “double blow to the gut,” exacerbating digestive symptoms and reducing gut bacterial diversity.

The study, presented at the 2026 American College of Gastroenterology Annual Scientific Meeting and led by Dr. Harika Dadigere of the New York University Grossman School of Medicine, provides insights for a broader understanding of the relationship between late-night eating, stress, and gut health, according to Verywell Health.

Researchers analyzed data from more than 11,000 participants in the National Health and Nutrition Examination Survey, measuring chronic stress using “stress load,” a composite metric based on body mass index (BMI), cholesterol, and blood pressure.

They found that individuals who consumed more than 25 percent of their daily caloric intake after 9 p.m. and experienced high stress levels were 1.7 times more likely to suffer from constipation or diarrhea.

A second dataset comprising over 4,000 participants in the American Gut Project yielded an even stronger result, showing that individuals with high stress and late-night eating habits were 2.5 times more likely to report gut problems.

The study also demonstrated that the adverse effects of nighttime eating extend beyond digestive symptoms; participants with high stress and late-night eating exhibited reduced diversity in their gut microbiome.

Chronic stress is known to affect digestion and contribute to symptoms of diarrhea and constipation. The gut and brain are connected via the “gut-brain axis,” a bidirectional communication system linking the central nervous system with trillions of microbes in the gastrointestinal tract.

When stress hormone levels rise, the brain signals the body to enter a “fight or flight” state. During this state, digestion slows down and food moves more slowly through the digestive tract, potentially altering the balance of gut bacteria.

This research adds to growing evidence in the field of chrononutrition, which examines how the body’s internal clock affects food processing, suggesting that meal timing may be as important as the quality of food consumed.

The circadian rhythm regulates sleep cycles, digestion, hormone secretion, and metabolism, and late-night eating disrupts these rhythms.

However, as the study is observational, it does not prove a direct causal relationship between nighttime eating and circadian rhythm disruptions. Nevertheless, it highlights an important pattern warranting further research.