Figure 2

Gut-brain interaction and bidirectional relationship of SD and FD. SD alters the circadian rhythm, affecting the release of neuromodulators and hormones such as melatonin, causing altered gut motility, visceral hypersensitivity, and immune dysregulation. Altered gut motility causing early satiety and abdominal discomfort is called PDS. Visceral hypersensitivity and immune dysregulation are associated with epigastric pain and are referred to as EPS. Sometimes with overlap (PDS-EPS). Symptoms of FD may cause waking or increased sleep latency, causing SD. Created with Biorender.com

SD: sleep disturbance; FD: functional dyspepsia; PDS: postprandial distress syndrome; EPS: epigastric pain syndrome