Ask A Scientist
What causes hiccups? Why do they repeatedly happen?
Asked by: Shayna Kent
School: West Middle School, Binghamton School District
Teacher: Mrs. Summerlee
Hobbies/Interests: Writing, drawing, talking with friends and playing lacrosse.
Career Interest: I want to be an author
Answer from Siva P. Adusumilli
Research Assistant and PhD Candidate, Binghamton University
Research Areas: Thin films, semiconductors, nano materials and solar cells
Interests/hobbies: Volunteering, playing with kids, listening to music and cooking.
A very interesting question, Shayna! Hiccups, most of the time, are attention seekers and make it nearly impossible to carry on a conversation. They occur without our conscious, stop suddenly or sometimes never stop and get annoying until we do something about it. Let's see what in our body, is causing the interesting phenomenon.
A hiccup is an unintentional movement (spasm) of the diaphragm, the large muscle at the base of the lungs, between the chest and abdoment. The diaphragm moves down when we inhale and up when we exhale, helping us to breathe. The phrenic nerves control the movement and sensation of the diaphragm. Any irritation to these nerves induces the spasm, which is followed by quick closing of the vocal chords, thus producing the distinctive "hic" sound or what we call, a hiccup.
The most common reasons for the short-term hiccups are having a full stomach or eating large meals, hot and spicy foods, drinking soda, sudden temperature changes and sudden emotions like excitement, stress and shock. Hiccups that last for more than 24-48 hours are caused when your phrenic nerves are damaged or when they are continuously being irritated, like a hair touching your eardrum. An average hiccup spell can last for a few minutes to a few hours, and for some people they can last for days and months, where immediate medical attention is needed. As mentioned before, hiccups make it nearly impossible to carry on a conversation and we try to cure them as soon as we sense them. There is no sure way to stop hiccups, but there are a number of suggested cures. Most of these suggestions are based on two main principles. One way to stop the hiccups is to overwhelm the vagus nerve with another sensation. By doing this, the vagus nerve will tell the brain that more important things have arisen than the hiccups. Another way is to interfere with the normal breathing, which increases the amount of carbon dioxide in the blood. As a result, the body gets more concerned about getting rid of the carbon dioxide, than making hiccups. These two practices are the most common. Other techniques include having someone surprise or scare you, which can overwhelm the vagus nerve by swallowing large amounts of water to interrupt the hiccupping cycle. You may also breath into a paper bag, or the way I get rid of the hiccups is to load my mouth with sugar, as the sweet sensation sensed by the nerve ending in my mouth will trigger the vagus nerve.