In this review, an integration of GI functioning is attempted with regard to its relationship to sleep, how this interaction may lead to complaints of sleep disorders, and the pathogenesis of some GI disorders. Data are presented to support the notion that sleep-related GER is an important factor not only in the development of esophagitis but also in the respiratory complications of GER. Although sensory functioning is altered markedly during sleep with regard to most standard sensory functions (eg, auditory), there seems to be an enhancement of some visceral sensation during sleep that seems to protect the tracheobronchial tree from aspiration of gastric contents reflux during sleep. Patients who have functional bowel disorders reveal an increase in sleep complaints compared with normal volunteers. The actual mechanisms of these disturbances remain somewhat obscure and studies do not demonstrate any consistent abnormalities in sleep patterns of these patients. Some studies show that autonomic functioning during sleep, particularly REM sleep, can distinguish patients who have IBS. Thus, the continued study of sleep and GI functioning promises to create a new dimension in the understanding of the pathophysiology of a variety of GI disorders.