It always seems to happen at the worst times. You are sitting in a school assembly, a very serious topic being presented by the headmistress on a detailed PowerPoint slide, and everyone is completely silent. Then, all of a sudden, you get hiccups; their unexpected arrival catches you off guard, coming too quickly for you to suppress the unmistakable sound. It’s a perfect example of an intensely embarrassing moment. Yet, on a more humorous note, most of us have also experienced the exact opposite: laughing so hard that we trigger hiccups, only to end up laughing even more.
One of my friends once told me that hiccupping was a sign that someone was thinking about you. This couldn’t be further from the truth, but it is a nice thought to have, nevertheless. So, let’s understand the actual science behind this instead.
Hiccups are involuntary spasms of the diaphragm, a dome-shaped muscle that separates the chest from the abdomen and plays a crucial role in breathing. Normally, the diaphragm contracts and flattens when you inhale to allow air into the lungs, then relaxes when you exhale so air can flow back out. However, when the diaphragm spasms involuntarily, it causes a sudden, sharp inhalation of air. This incoming air hits the voice box, causing the vocal cords (the glottis) to snap shut abruptly, which produces the characteristic “hic” sound.
These spasms usually occur due to irritation of the nerves that control the diaphragm, particularly the phrenic nerve. This irritation can be triggered by several everyday factors. For example, eating too quickly or too much which can stretch the stomach, causing irritation to the diaphragm. Carbonated drinks can cause gas buildup, leading to similar irritation. Strong emotions such as stress, nervousness, or excitement can also trigger hiccups, as well as sudden temperature changes, such as drinking a cold drink immediately after a hot one.
Interestingly, for most people, hiccups do not appear to serve any useful purpose. They are considered a reflex, and while some scientists suggest they may be an evolutionary leftover from early amphibians (such as tadpoles, which use a similar reflex when breathing), hiccups do not have a necessary function in modern humans.
While many people believe that being scared, drinking water quickly, or breathing in strong smells will cure hiccups, there is little scientific evidence to support most home remedies. However, some medically suggested techniques include holding your breath for several seconds and then breathing out slowly or breathing into a paper bag help to increase carbon dioxide levels in the blood, which is thought to help relax the diaphragm and stop the spasms.
Hiccup episodes that last less than 48 hours are usually harmless and very common. Most people experience brief hiccups that resolve on their own after a few minutes. However, hiccups that last longer than 48 hours are rare and may be linked to underlying medical conditions. Persistent hiccups can sometimes be caused by structural, infectious, or inflammatory disorders. For example, irritation from a sore throat, or more serious causes such as a tumour or cyst in the neck, can lead to prolonged hiccups. Chronic medical conditions such as encephalitis, meningitis, diabetes, or kidney failure have also been linked to long-term hiccups, and in some cases, medical procedures involving anaesthesia can trigger them.
So, while hiccups are usually harmless and often just an embarrassing interruption at the worst possible moment, they are actually the perfect example of how closely the brain, nerves, and respiratory system work together (even when things don’t go quite to plan).
I hope you learnt something new and stay tuned for next week for a new question and a new answer in my series ‘questions that need answers’.
