healthHealth and Medicinehealthhealth

What Are Fever Dreams?

Running a temperature can lead to some pretty freaky fever dreams.


Rachael Funnell


Rachael Funnell

Digital Content Producer

Rachael is a writer and digital content producer at IFLScience with a Zoology degree from the University of Southampton, UK, and a nose for novelty animal stories.

Digital Content Producer

what are fever dreams
Dreaming of elephants foraging for giant broccoli at the beach? If you're unwell, that's a fever dream, baby. Image credit: PCH Vector /

Dreaming can be a trip at the best of times – but when we’re ill, our subconscious can get very creative while we’re unconscious. These vivid, often bizarre, and sometimes distressing dreams are known as fever dreams, and there are several explanations as to why they occur when we are sick.

Fever dreams vs normal dreams

We dream during a stage of sleep known as rapid eye movement (REM), during which – surprise surprise – our eyes flit about rapidly. Dreaming is a normal part of life that scientists suggest can benefit our memory and perception of reality, but fever dreams can be a very different experience.


Fever dreams will sometimes be quite nightmarish, playing out the bizarre in our brains to the extent that it can be upsetting and leave us with an unpleasant feeling when we wake up.

fever dreams
The approximate length of time spent in each sleep stage during a single sleep cycle. Non-rapid eye movement (NREM) sleep is followed by REM and sometimes brief wakefulness, but when we wake in the night we can be more likely to recall our dreams vividly, as is often the case for fever dreams. Image credit: By Schlafgut - Own work, CC BY-SA 3.0

What are fever dreams

There’s not yet evidence to suggest fever dreaming is in itself harmful in any way other than the potential for mental upset, but they occur in association with a high temperature and that can be dangerous. 

A healthy body temperature can vary from person to person, but most people will say that the average body temperature is 37°C (98.6°F), a number that stems from a medical book by German physician Carl Reinhold August Wunderlich in 1868. However, more recent research suggests that this has dropped to nearer 36.6°C (97.88°F).

Fever dreams occur when our temperature goes beyond its healthy range, and overheating has some pretty nasty effects on our bodies. That spike in temperature can be in response to infection or disease, and once you get the underlying illness under control, the high temperature and fever dreams should go away.

Why do we get fever dreams

Part of the reason we get fever dreams is to do with the fact that we’re more likely to wake up in the night when we’re unwell. In a normal night’s sleep, you’ll run through several rounds of REM, but with each subsequent sleep cycle, your memory of the dreams that came before is effectively wiped. However, if you wake up, you’re more likely to commit the dream to memory, making it seem more vivid in your mind.

The same effect can occur as a result of stress, which is why a lot of people reported having freakier dreams during the worst of the pandemic.

Another reason we get fever dreams when we’re sick is thought to be due to the effect heat has on our poor brains. Overheating can disrupt proper cognitive function, so as our brain struggles on with unfavorable working conditions its content suffers, which as creators we find highly relatable.

How to stop having fever dreams

The key to stopping fever dreams is to remedy the underlying condition that is causing your temperature to rise. It could be something reasonably benign, like a cough or a cold – but if your temperature is raised and you don’t know why, it’s best to check in with your healthcare provider for advice.


It may be that treatment can speed up the process of lowering your temperature, or you may need to just wait it out as the illness naturally takes its course. To fill the time, why not jot a few of those fever dreams down? As they say, everything is content.


healthHealth and Medicinehealthhealth
  • tag
  • sleep,

  • health,

  • dreams,

  • fever,

  • REM sleep