Singultus (hiccup) is common, usually transient, and only rarely indicative of disease. If it persists, it can be highly bothersome, potentially interfering with sleep and leading to depression and physical exhaustion. It is presumed to be due to a disturbance in a reflex arc that includes the brainstem, the phrenic nerve, the vagus nerve, and the sympathetic chain. It can be induced by mechanical irritation (e.g., gastric distention), metabolic or toxic irritation (e.g., alcohol, cigarette smoke), infectious processes, emotional disturbances, and, rarely, neurological diseases.

More Info: www.ncbi.nlm.nih.gov