Circadian rhythm and sleep influences on digestive physiology and disorders

Figures & data

Table 1 Circadian and sleep influence on digestive function

Digestive function	Circadian influence	Sleep-stage influence
Saliva production	Possibly pH	Yes
Swallows/esophageal motility	No	Yes
Gastric acid secretion	Yes	Unclear
Gastric motility	Unclear	Yes
Intestinal absorption	Yes	Unclear
Intestinal motility	Potentially	Yes
Colonic motility	Potentially	Yes
Rectum/anal function	Potentially	Yes

Figure 1 The circadian pattern of gastric acid secretion across a 24-hour period.

Notes: The relationship between basal acid secretion (total H= in Eq/h), volume (mL/h), and gastric pH is shown for a group of healthy male subjects. Note the peak acid secretion is just before midnight. Copyright © 2006, John Wiley and Sons. Reproduced from: Moore JG. Circadian dynamics of gastric acid secretion and pharmacodynamics of H2 receptor blockade. Ann NY Acad Sci. 1991;618:150–158.²²
Abbreviations: H+, acid secretion; h, hour; mEq, milliequivalent.

Table 2 Various roles of melatonin in gastrointestinal (GI) disorders

Role	Mechanism	GI disorder	Reference(s)
Improves mucosal regeneration via downstream circadian influence	Produced by neuroendocrine cells of stomach and duodenal mucosa; inhibits gastric acid release, increases gastric blood flow	Ulcers	30
Improves mucosal regeneration	Improves villus height, total mucosal thickness, and cell mitosis	Ulcers	31
Measure of circadian rhythm function		IBS and others	70,71
Anticarcinogenic	Unclear	GI cancers	78–81
In development or control of IBD	Proposed: synchronization of gut circadian rhythms, direct modification of intestinal permeability, antioxidant effects, change in blood flow, improvement in mucosal repair, or immunoregulatory function	IBD	93
Slow GI motility and smooth-muscle cell contraction	Interaction with serotonin receptors present on the vagal afferent fibers and inducing vagovagal inhibitory reflexes	IBS and others	94
Prevention of dextran sodium sulfate-induced colitis	Prevents development of colitis when given as pretreatment, mechanism unclear	Colitis	95

Abbreviations: IBS, irritable bowel syndrome; IBD, inflammatory bowel disease.

Moore JG. Circadian dynamics of gastric acid secretion and pharmacodynamics of H2 receptor blockade. Ann N Y Acad Sci. 1991;618:150–158.

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