Explainer | The human body 101: why do we spasm, shiver or feel a lump in our throats?

That shiver-down-the-spine sensation may occur because of something we ate or drank, or saw, how we are feeling or a memory that we’ve triggered

That annoying, falling-off-a-cliff jolt just as you drop off to sleep? Up to 70 per cent of us experience them, usually when we are overtired

Reading Time:4 minutes

Shivers down the spine, a spasm as you drop off to sleep – these are all body reflexes that we’ve all had to deal with at some point in our lives. But why do we experience them? Photo: Shutterstock

Published: 8:15pm, 10 Jan 2021Updated: 8:15pm, 10 Jan 2021

You must have felt them? Those strange involuntary spasms over which you apparently have no control: a leg that kicks out as you drop off to sleep and startles you so that you are briefly wide-awake again? A shiver that runs down your spine and makes you tremble despite being safe and in the sunshine, or a lump that hardens in your throat as you struggle to swallow and hold back tears?

What causes these peculiar, and strangely common, bodily reflexes?

That shiver-down-the-spine sensation may occur for several reasons, and can include “perceptual, biochemical, memory, mood, emotion – all neurological” according to Lyelle Palmer, professor emeritus in the department of special education at Winona State University in the US state of Minnesota.

In other words, what we see, or eat and drink, our recall of past events, and how we are feeling are all possible causes.

That shiver-down-the-spine sensation may occur for several reasons, including perceiving something that triggers memories, or the sight of creepy images. Photo: Shutterstock

It most certainly involves the vagus nerve – the largest nerve in the autonomic nervous system which extends from the brain to the colon and plays a key role in heart, lung and digestive function. Strong vagal tone helps you relax faster after experiencing stress, while weak vagal tone is associated with chronic inflammation.

Explainer | The human body 101: why do we spasm, shiver or feel a lump in our throats?

That shiver-down-the-spine sensation may occur because of something we ate or drank, or saw, how we are feeling or a memory that we’ve triggered That annoying, falling-off-a-cliff jolt just as you drop off to sleep? Up to 70 per cent of us experience them, usually when we are overtired

That shiver-down-the-spine sensation may occur because of something we ate or drank, or saw, how we are feeling or a memory that we’ve triggered

That annoying, falling-off-a-cliff jolt just as you drop off to sleep? Up to 70 per cent of us experience them, usually when we are overtired