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Can a Dream Warn You About Cancer?

Prodromal dreaming, or the idea that dreams can alert us to a health problem before it’s clinically diagnosed, isn’t a widely accepted theory. But a growing body of work has uncovered links between dream patterns and certain health conditions.

By Diane Bacha
Jan 19, 2021 2:30 PMSep 6, 2023 3:12 PM
Woman frowning while having a bad dream
(Credit: Stasonych/Shutterstock)


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Chances are it has happened to you or someone you know: dreaming that your teeth are falling out. Not quite a terrifying nightmare, but definitely not pleasant.

Could it be that you were frightened of the tooth fairy as child and your brain is processing unpleasant thoughts? Or do you need to visit your dentist?

Dreaming About Health Issues

The connection between dreaming and health has been studied in the search for insights about mental health, disease, the brain, and sleep. Studies show, for instance:

Few of these studies, however, help if you want to know whether your tooth dream justifies a trip to the dentist. When it comes to whether you should consider dreams to be clues about your health, the rule of thumb seems to be: Maybe sometimes, if you pay attention and use common sense.

“In general terms, if you’re having bad dreams and nightmares, and if these are upsetting you, then that’s something you should do something about,” says Tore Nielsen, director of the Dream & Nightmare Laboratory at the University of Montreal in Quebec. He calls dreams and nightmares “dipsticks” into your unconscious. “They can tell you something needs attention.”

Read More: Why Do We Dream? Science Offers a Few Possibilities

Can Dreams About Cancer Predict a Diagnosis?

The concept that dreams and their content can signal specific health issues isn’t widely accepted. To treat dreams as useful tools in this way “is controversial in broader medical professions,” says Deirdre Leigh Barrett, a dream researcher at Harvard Medical School, past president of the International Association for the Study of Dreams, and author of The Committee of Sleep.

But she and others point to intriguing observations that could suggest there’s more to discover about prodromal dreaming, or dreams that predict a condition before it can be otherwise detected. 

Barrett’s book describes two examples of people whose dreams alerted them to spots on their body that turned out to be cancerous. In one case, the dreamer had no previous recollection of noticing the spot. He dreamed about a panther biting him on his back, woke up and found a mark there, then visited a physician. In the other case, the dreamer had noticed a spot but was assured it was nothing. She then had a series of dreams about it —one of them with very pointed directions to get it checked. So she had the spot tested; it was early melanoma. 

Anecdotes like these are not uncommon, and some are far more dramatic. They pose the possibility that dreams can remind us to address something we’ve overlooked or can even warn us before the problem is detectable.

Barrett sees it this way: “I think dreams can access anything in our body or our mind, in the broadest sense, including things we’re not at all conscious of.” That could include a signal you were too distracted to process while awake. Or it could mean the dream is picking up subtle responses in the body when there’s something wrong. Her research reveals a greater incidence of dreams about slow-growing diseases such as cancer, which could be present in the body long before it’s detected. “I think that dreams sometimes tell people about an illness that they’re not already aware of, and [before] any very obvious clinical symptom.”

Carlyle Smith, a professor emeritus of psychology at Trent University in Peterborough, Ontario, is known for his ground-breaking research into the role dreams play in memory and learning. He’s now retired, but continues to plumb the possibilities of dreams. His book Heads-Up Dreaming explores the potential for anyone to use dreams as tools to guide decisions, including health decisions.

Read More: Do All Dreams Have Meaning?

Vivid Clues From Prodomal Dreams

The prodromal dreams Smith has observed tend to be very vivid, often very specific, and insistent — the dreamer will experience multiple episodes over time that add new details. “Several dreams of this kind on the same topic can be pooled to get full information,” he says, adding that negative emotions in a dream tend to be stronger with a more serious condition.

“You can imagine some kind of neural theory, where a part of your body is not working right and somehow there’s a message sent to your dreaming brain” as a kind of early warning, Smith says. But so far there’s no substantiated theory to explain that. “There just isn’t anything in the traditional physiological, neurophysiological system.”

Smith continues to pursue his own research while tracking research around the globe that might offer clues to the prodromal dream puzzle. He’s under no illusion that prodromal dreams will become an accepted phenomenon any time soon, but he’s not losing sleep over it. “Even the idea that sleep is important or has anything to do with memory were things that people poo-pooed in the old days.”

Nielsen, Barrett, and Smith encourage people to pay attention to their dreams, especially ones that recur or are notably more vivid than others. They could be symbolically important — pointing out a stressful situation you need to manage, for instance. Or they could be something else. “I would at least entertain the idea that there is something physical going on,” Barrett says.

Read More: The Strange Science of Lucid Dreaming

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