Gastrointestinal physiology and digestive disorders in sleep

Digestive system and sleep is an excellent example of brain-body interaction. New advances in measuring techniques provide an opportunity to evaluate physiology that is dependent upon the sleep/wake state or circadian rhythm and potentially differentiate between normal and pathological conditions.

It has been demonstrated that sleep and circadian factors influence appetite, nutrient absorption, and metabolism. Disruption of sleep and circadian rhythms may increase vulnerability to digestive disorders, including reflux, ulcers, inflammatory bowel issues, irritable bowel disease, and gastrointestinal cancer.

Sleep deprivation and impaired sleep quality have been associated with poor health outcomes. Many patients experience sleep disturbances, which can increase the risk of medical conditions such as hypertension, obesity, stroke, and heart disease as well as increase overall mortality.

Proinflammatory cytokines, such as tumor necrosis factor, interleukin-1, and interleukin-6, have been associated with sleep dysfunction. Alterations in these cytokines have been seen in certain gastrointestinal diseases, such as gastroesophageal reflux disease, inflammatory bowel disease, liver disorders, and colorectal cancer. Sleep disorders have been linked to neurocognitive effects such as slower response time, impaired attention, and increased likelihood of falling asleep at work. Most studies suggest that the daily sleep requirement for adults is 7 to 9 hours per night.

The connection between the brain and the gastrointestinal system is imperative to the regulation of the digestive tract and maintenance of the gut immune system.

The gut-brain axis works through mechanisms that involve immune activation, intestinal permeability, and enteroendocrine signaling. This bidirectional network involves the central nervous system (CNS), autonomic nervous system, and enteric nervous system (ENS). The network incorporates sympathetic and parasympathetic activity, which drive afferent signals through enteric and vagal pathways to the CNS and efferent signals from the CNS to the intestine. There are neural and hormonal influences that allow the brain to modulate the activity of intestinal cells such as interstitial cells of Cajal, enterochromaffin cells, and smooth muscle cells. This dynamic relationship between the brain and the gastrointestinal system involves feedback loops, which also influence the circadian rhythm and sleep regulation pathways. This suggests that there is a relationship between sleep disturbances and physiologic changes of the gastrointestinal tract.

Obesity plays a significant role in multiple gastrointestinal disease processes, such as GERD, hepatic steatosis, and potentially colon cancer. Obesity is a major risk factor for sleep apnea, resulting in poor sleep, which can, in turn, lead to gastrointestinal disease. A strong focus on weight reduction can improve existing symptoms in patients with underlying gastrointestinal conditions. Furthermore, weight reduction can potentially reduce the risk of a patient developing certain disease states.