Dreams are awe-inspiring phenomena that remain a mystery despite being well-researched by scientists. While they seem to have some basis in our realities, the events of our dreams make little sense and are quite random.

When we get sick, many of us develop fevers to fight off infection. During a fever, you may expect regular symptoms, such as chills, exhaustion, muscle ache, and headaches; but one symptom you may not expect is vivid, intense nightmares—otherwise known as “fever dreams.”

In our post, we discuss fever dreams and talk about why we tend to have unpleasant dreams when our bodies sleep off sickness.

When Do Fever Dreams Happen?

When your body is combating illness, you may experience a fever dream. Fevers occur when your body’s temperature exceeds the average 97 to 99 degrees Fahrenheit. Once your body temperature spikes 2 degrees higher than average you’re considered “feverish;” but typically, spikes over 3 and four degrees, or anything over at least 101 degrees Fahrenheit, is considered a true fever.

As a result of your immune system fighting off pathogens, heat-sensitive microorganisms, your body temperature rises to kill these harmful invaders. Viruses, heat exhaustion, a bacterial infection are all common causes of a fever. Certain medications, tumors, and immunizations can also ignite a fever.

What Are the Dreams About?

The subject matter of fever dreams varies between individuals, though they are mostly be summed up as negative and nightmarish. A 2016 study found 94 percent of participants had “more bizarre, more emotionally intense, and often negatively toned” fever dreams when compared to a healthy mind’s dream.

Fever dreams are commonly filled with odd scenes, and they’re more easily recalled in comparison to regular dreams. Some sleepers even report recurring nightmares from childhood popping back up in their fever dreams. Nonetheless, the themes of these dreams are often anxiety-inducing, and they have the potential to cause disruptions in regular sleep patterns.

Common occurrences in fever dreams include:

  • A threatening and stressful force
  • Blackness closing in on you
  • Oversized creatures and strange, unfamiliar beings
  • Vertigo
  • Feelings of helplessness, claustrophobia, or the inability to move or breathe
  • Never-ending or unresolvable events
  • Little social interaction
  • Heat sources—potentially correlated to elevated body temperature—such as burning clouds and melting statues or being surrounded by lava

Why Do Fever Dreams Occur?

Scientists have not been able to determine exactly why we experience fever dreams, as the studies on their occurrences are a bit scarce.  However, many assume the vivid dreams are associated with the intense spike in body temperature during a fever.

Interestingly enough, fever dreams don’t appear to be incredibly common. A study observing fever symptoms found that only 11 percent of people had fever dreams or hallucinations.

Fever dreams are believed to happen more frequently during a person’s Rapid Eye Movement (REM) sleep stage. During this stage, dreams are more notably vivid even when you’re healthy. Regardless, both regular and fever dreams can occur during any sleep stage.

Throughout the day, our brain keeps your temperature regulated. During REM sleep, however,  our bodies do not regulate temperature as well since our brains are at rest. As a result, body temperature can fluctuate. High body temperature is associated with cognitive impairment and confusion, and this can also lead to a fever dream.

Those with higher stress levels are more prone to nightmares, even when they aren’t sick. Stress is hard on the body, so many researchers believe the stress on the body as it fights off illness is one reason we experience unpleasant dreams during a fever.

Frequently Asked Questions

What’s the difference between lucid dreams and fever dreams?

Lucid dreams and fever dreams bear little resemblance, but they’re often compared because both types of dreams are detailed and easily remembered.

  • Lucid dreaming occurs when a person is aware they’re asleep and within a dream. Due to their awareness, people are sometimes able to control their dreams, and this helps to reduce anxiety, control nightmares, and boost creativity.
  • Fever dreams, conversely, are negative dreams most sleepers wish to avoid. In fever dreams, the sleeper is unaware they’re dreaming and may feel helpless, stressed out, or anxious since they’re unable to control what’s happening.

Do fever dreams mean anything?

The actual content of a fever dream is often strange and bizarre, though often meaningless. The weirdness of a fever dream is merely a sign of the stress on your body due to being sick and should pass once you’re feeling better.

What is the longest sleep stage?

75 percent of sleep time is spent in NREM sleep, or non-rapid eye movement sleep. The four NREM sleep stages range from light to deep sleep. Of those four stages, stage 2 (NREM2) lasts between 30 to 60 minutes, making it the longest sleep stage.

How long do fever dreams last?

Similar to a regular dream, the length of fever dreams vary, and it’s difficult to pinpoint the exact duration. They may only be a few seconds, but some dreams can last from 20 to thirty minutes.

How can I prevent a fever dream?

Unfortunately, fever dreams cannot be controlled or prevented once you’re sick with a high body temperature. Similar to hot flashes and achiness, fever dreams are a symptom of being sick.

The best option to prevent a fever dream is by taking measures to lower your body temperature. Stay cool and hydrated, sleep well, and if recommended by a physician, take an over-the-counter medication such as ibuprofen.


Fevers and fever dreams, albeit exhausting and bizarre, are beyond our control and not something to cause worry. While they are not the most common symptom of illness, fever dreams are not out of the ordinary. Experiencing a fever dream is merely a sign of your body working hard to combat a virus, but once you’re healthy again, the unpleasant dreams will go away naturally.

This article is for informational purposes and should not replace advice from your doctor or other medical professional.