The COVID-19 pandemic had documented effect on people’s dreams – even those who haven’t contracted the infection. But it has long been known that just fever, regardless of the underlying cause, causes strange dreams.
Called fever dreams, these images are often more vivid and unpleasant than ordinary dreams. And according to the National Sleep Foundation, they’re also likely to develop a strange, Alice in Wonderlanda similar world that includes such psychedelic elements as moving walls and melting objects.
An extraordinary emotion
Fever dreams are difficult to study. (After all, you can’t easily visit a sleep lab when you have the flu.) But in 2020, dream researchers Michael Schredl of the University of Heidelberg in Germany and Daniel Erlacher of the University of Bern in Switzerland surveyed 164 people. They found that fever dreams live up to their reputation for being more than strange, but they also involve more negative and less positive emotions than other dreams.
“Normal” dreams often involve interactions with people, while in fever dreams people appear less frequently. Not surprisingly, fever dreams are also more likely to include health-related themes and a strong sense of temperature.
Here is an excerpt from a fever dream as reported in 2020 Survey:
I’m going to a city that’s in a valley, maybe Italy. […] Suddenly a hot wind blew. I don’t know where I am (in the city) and it’s getting hotter. I lost my shawl and also my shoes; I can feel the relatively cool cobblestones of the street. I have the impression that I must escape quickly. The air is so hot it hurts to breathe. […] I see a red glow in the corner of my eyes and turn to see a huge ball of lava coming down the mountain towards the town and me. I run faster and faster, the air gets hotter and hotter, the lava ball changes directions, chasing me and not touching the houses. The lava ball seems to be on a mission to catch me. As the lava ball catches up, I wake up.
Being chased by a giant ball of lava might seem a bit extreme, but other research shows that dreams often include bits of the waking experience. They call it continuity hypothesis. So if you are burning with a fever, dreaming of a ball of lava is related to the worries of your waking life.
Weird brain function
Schredl and Erlacher also raise the possibility that cognitive impairment caused by fever may contribute to the strangeness of dreams. “The basic idea is that an ‘overheated’ brain doesn’t function properly and therefore dreams are weirder,” they writepointing to previous research by Schredl, who showed that the severity of psychotic symptoms in schizophrenic patients during the day was related to the degree of strangeness of their dreams at night.
Rest assured though, fever dreams are not harmful in themselves. Instead, they seem to be a symptom of the fever rather than an indication that anything else is wrong. If you’re sick with a fever, the NSF advises, take the usual precautions and try not to let the strange dreams scare you.
Of course, there is still much work to be done to understand why fever dreams are so strange. But if you’ve had one, take comfort in the fact that you’re not alone. (And maybe consider yourself lucky you didn’t spend the night running from a giant ball of lava!)