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Fever Dreams: Why Do We Have Weird Dreams When We’re Sick?

Fever Dreams: Why Do We Have Weird Dreams When We’re Sick?

Some fever dreams are linked to adolescent memories, while others are just bizarre once-off occurrences. Regardless of their origins, fever dreams can be scary and unpredictable.

As the name suggests, fever dreams are intense and vivid dreams we experience due to having a high body temperature. They can be uncomfortable for the dreamer, and in many cases, there are also physical symptoms that can help you or someone else identify when a fever dream has occurred.

Fever dream definition

Fever dreams are dreams, mostly with negative connotations, triggered when the body increases in temperature at night. Normal body temperature for adults falls between 97 and 99°F. Anything over 2 degrees higher than this can be considered a fever.

Although there is a sense of bewilderment about the intricacies of dreaming in general, such as why we dream and what they mean, there is enough research to differentiate between different types of dreams.

Fever dreams are unique because they only occur when you feel sick.

How do fever dreams occur?

Like other dreams and nightmares, fever dreams occur during the rapid eye movement (REM) stage of the sleep cycle. During REM sleep, brain wave activity is high and is often compared to having the same activity level during wakefulness, which is why most dreams occur during this stage.

The brain is responsible for natural thermoregulation. And an increase in body temperature is the brain's response to fighting illness. Fever happens when a small almond-sized section of the brain called the hypothalamus spikes body temperature to combat pathogens.

Telltale signs of fever are easily recognizable: body aches, sweating, intense fatigue. At the peak of fever, the body is weakest, which is when fever dreams tend to occur.

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What happens during a fever dream?

Fever and sickness can heighten emotional instability and increase sensitivity, leaving you more vulnerable to negative thoughts. This may be why the majority of fever dreams are negative and can even be distressing and scary.

A 2016 retrospective study analyzed fever dream experiences to determine the nature of fever dreams. Sixty-four participants in the study reported their fever dreams were more bizarre and emotionally intense than other dreams they have had. Researchers also found that 94% of dreams were negative.

While there is no conclusive evidence about the exact reason why fever dreams occur, researchers link the ‘overheating’ of the brain to a drastic reduction in normal cognition, which is the reason why dreams during fever can be weird, scary, and often disoriented.

In a 2020 online survey about the nature of fever dreams, frequency, and vividness, many respondents cited, “The most intense feelings were weakness and helplessness.”

Fever dreams can also feature negative childhood memories, or they can play out as recurring dreams that surface each time you have a fever. Again, heightened emotions and poor cognitive function are said to cause this phenomenon.

Are nightmares and fever dreams the same?

Are nightmares and fever dreams the same?

Both nightmares and fever dreams have correlating factors, but they are different. Fever dreams are triggered by fever, whereas nightmares don’t depend on physiological factors for them to happen.

Another unique characteristic of a fever dream is that it can be much easier to recall than nightmares. When you have a high body temperature, it can be easy to wake up from a negative fever dream, so people tend to remember them more.

Fever dreams stop once body temperature drops back to normal, and you begin to feel better. Nightmares can stick around and happen at various times throughout the year and can be triggered by a wide range of factors such as sleep deprivation, a traumatic incident, or even a scary movie.

Most people group dreams into two categories: good dreams and bad dreams. However, there are five types of dreams that most people have at some point or another.

Just like fever dreams, all dreams have a unique set of characteristics that can help differentiate them. Fever dreams are unique as they are conditional based on your health. In contrast, other dreams depend on external events.

Can you prevent fever dreams?

While there is no surefire method of prevention when it comes to fever dreams, treating your fever and limiting distractions may help.

Apart from any medications you may be taking, tweaking your sleep routine when you're sick may help you sleep better.

Here are some easy tips you can follow to help you sleep when you feel under the weather:

How to regulate temperature

How to regulate temperature

Managing bedroom temperature while you have a fever can benefit how well you sleep. Whether you have a fever or not, keeping your room cool is recommended to help regulate body temperature and reduce the chance of overheating.

Sleeping hot is a major sleep disruptor. Are you someone who kicks the sheets or frequently wakes up in night sweats? This is an obvious sign that your bedroom environment isn’t designed with good ventilation. The ideal bedroom temperature for quality sleep is between 60 to 67°F, so ensure you set the thermostat correctly, especially if you notice signs of sickness approaching.

In addition to making sure you have proper airflow, take a close look at your mattress and bedding. Most hot sleepers, or people who sweat profusely, don’t invest in the correct type of mattress and bedding.

It’s best to sleep on a memory foam or a hybrid mattress for perfect airflow all year round. Memory foam is widely considered the most comfortable mattress as it conforms to the body, no matter what position you sleep in. Memory foam is also highly porous, so air flows through the layers with ease.

Another popular choice is a hybrid mattress. Hybrids tend to have a higher density as the construction combines both contouring memory foam and encased coils.

Regular hot sleepers or people who overheat very easily when fevers run high can significantly benefit from sleeping on a cooling mattress.


Fever dreams occur when body temperature increases above 101°F when you are sick. In most cases, fever dreams won’t last for long. However, everyone is different. If you find your dreams are lingering for longer than they should and are causing you discomfort, consider seeing a doctor.

Your Turn...

Do you experience fever dream? Share your thoughts in the comments. 

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Disclaimer. We love sleep and we want you to get the best sleep possible. But we do not provide medical advice. This blog is intended for informational purposes only. It is not a substitute for professional medical info, diagnosis, or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on our blog.

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Certified Sleep Science Coach

Written by Monica Chinsami, Certified Sleep Science Coach

Monica is a writer who is passionate about the connection between wellness and sleep. She believes sleep has the power to unlock our greatest potential for health and happiness. Topics she's covered range from well-being, to the latest trends in sleep health and bedroom aesthetics. Monica holds a BA in Journalism from Monash University and is a Certified Sleep Science Coach.