Circadian Rhythms in Gastroenterology: The Biological Clock's Impact on Gut Health

Chronic gastrointestinal (GI) diseases, including functional, inflammatory, and neoplastic conditions, are rising globally, partly due to modern lifestyles. The circadian rhythm, regulated by the central clock in the hypothalamus and synchronized with peripheral clocks in the gastrointestinal organs, orchestrates GI functions in response to environmental cycles. This clock is influenced by cues such as light, sleep, and eating times. The circadian machinery prepares the host to cope with environmental conditions to adjust cellular and organ function accordingly. Modern behaviors—like nighttime light exposure, travel across time zones, shift work, mistimed eating, and social jet lag—disrupt the circadian clock, affecting GI processes such as digestion, absorption, motility, intestinal barrier function, immune function, and the microbiome, promoting not only GI pathology, but also systemic inflammatory and metabolic disorders.