Why we get the chills when we’re burning up with fever
New research has identified the brain circuit behind fever-related chills and why we burrow under blankets when we’re sick.
- 13 February 2026
- 4 min read
- by Linda Geddes
At a glance
- When we have an infection, we often feel chills and look for blankets or warmth – behaviours that help the body reach a higher temperature. But how the brain creates this sensation has remained unclear.
- A new study in rats, published in the Journal of Physiology, suggests that an immune molecule called prostaglandin E₂ triggers this behaviour by acting on neurons in a brainstem region that normally carries cold signals from the skin. These neurons communicate with an emotion-processing area of the brain, producing an unpleasant sensation that drives the rats to seek warmth.
- This warmth-seeking behaviour can help the body reach a higher temperature, alongside involuntary heat-producing responses such as shivering.
You’re burning up, yet you can’t stop shivering. It’s a common experience during illness, but exactly how and why the brain produces this shivery sensation during fevers has long puzzled scientists.
Now, new research has identified the neural pathway underpinning it, revealing that the discomfort may be part of a built-in survival response that helps the body fight infection.
The findings could help scientists better understand how the brain links immune signals to behaviour and emotions during illness, with potential implications for treating fever-related discomfort and disorders that disrupt normal temperature regulation.
Why do we experience fever?
Fever is widely viewed as part of the body’s defence against infection, as higher temperatures can slow the growth of invading microbes and help immune cells work more effectively.
As a fever develops, people often experience chills: an unpleasant sensation that encourages them to seek warmth, put on extra layers or turn on a heater. Such actions probably help the body reach and maintain its higher temperature, but until now scientists didn’t understand how infection makes us perceive temperature differently.
What was known, is that when the immune system detects invading microbes, it releases signals that prompt the brain to produce prostaglandin E₂, a molecule that turns up the body’s internal thermostat.
Until now, most research has focused on the automatic responses that follow, such as shivering and burning fat to generate extra heat. Less clear, was how the brain creates the uncomfortable sensation of chills
Prof Kazuhiro Nakamura at Nagoya University in Japan and colleagues had previously shown that a region deep in the brainstem, called the lateral parabrachial nucleus, relays temperature information from the skin to areas of the brain that influence both body temperature and emotions.
Because this region also responds to prostaglandin signals during infection, they suspected it might be the link between the immune system and the drive to seek warmth while running a fever.
To test this, they carried out a series of experiments in rats, which involved stimulating prostaglandin receptors in this brain region and tracking changes in their warmth-seeking behaviour: measured by how long the animals spent standing on a warm metal plate (39°C) or a neutral plate (28°C).
Have you read?
How does the brain produce fever-related chills?
The research, published in the Journal of Physiology, found that prostaglandin E₂ acts on a specific group of neurons in this brainstem region, and boosts the transmission of cold signals to an emotion-processing area of the brain called the central amygdala, similar to what happens when rats are actually exposed to a chilly environment.
“The consequent increase in cold sensitivity likely represents the chills that humans often experience when developing a fever, accompanied by an unpleasant emotion,” the team said.
This heightened sensitivity to cold is thought to drive the animals to seek warmth – a behaviour that can help the body reach a higher temperature, alongside automatic heat-producing responses such as shivering.
“From an evolutionary physiological perspective, our findings suggest that behavioural changes linked to fever are adaptive survival strategies rather than merely symptoms of infection,” Nakamura said.
Future research will need to determine whether this circuit is conserved in humans and to clarify its role in chronic inflammation, thermo-regulatory disorders and infectious diseases.
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