You’ve probably grown up hearing lots of homegrown advice about what you should or shouldn’t eat, whether it’s before jumping into the pool or before going to bed.

In fact, your grandmother or your mom probably told you that eating cheese before bed causes nightmares. Now, a team of Canadian sleep researchers has spent years testing this very hypothesis on more than a thousand college students. And the results support Abuela’s rule more than one might expect.

The Cheese Rumor Finally Has a Paper Trail

The study, led by Dr. Tore Nielsen of the Dream & Nightmare Lab at the Université de Montréal, surveyed 1,082 psychology students at MacEwan University about what they ate and what they dreamed. They then compared the responses against validated sleep and nightmare scales. It was published July 1, 2025, in Frontiers in Psychology, titled “More Dreams of the Rarebit Fiend” — a reference to a real early-1900s comic strip in which characters blamed their bizarre dreams on Welsh rarebit, a spicy melted-cheese dish eaten right before bed.

Just over 40% of participants said certain foods changed how well they slept. 24.7% said it was for the worse and 20.1% for the better. A smaller group, 5.5%, said food went further and actually altered their dreams, a phenomenon the researchers call food-dependent dreaming. That group scored meaningfully higher on the Nightmare Disorder Index than everyone else, driven entirely by how often they had nightmares.

Dairy and Sweets Are the Main Suspects

Ask participants who blamed food for their dreams which food, and two answers led the pack. Desserts and sweets accounted for 31% of dreams that turned disturbing, dairy for another 22%. For overall sleep quality, sweets and desserts were also the top culprit, named by 22.7% of participants, followed by spicy food at 19.5% and dairy at 15.7%. Fruit, herbal tea, and vegetables, by contrast, were the foods people credited most with a better night’s sleep.

Winsor McCay’s characters “frequently blamed their presleep ingestion of cheese dishes for occurrences of bizarre dream and nightmare events,” according to the study. Researchers then draw a new theory: McCay may have been lactose intolerant himself, decades before the condition had a clinical name.

Lactose Intolerance Is Doing the Real Damage

People with lactose intolerance and food allergies reported significantly more frequent and more severe nightmares than everyone else. The connection ran through gastrointestinal symptoms — the bloating, cramping, and general distress that show up after eating something the body can’t process well — rather than through dairy’s flavor or fat content. Statistically, that GI distress explained why lactose intolerance predicted nightmares at all.

“Nightmares are worse for lactose-intolerant people who suffer severe gastrointestinal symptoms and whose sleep is disrupted,” Nielsen said in a statement reported by Food & Wine. “This makes sense, because we know that other bodily sensations can affect dreaming. Nightmares can be very disruptive, especially if they occur often, because they tend to awaken people from sleep in a dysphoric state. They might also exhibit sleep-avoidance behaviors. Both symptoms can rob you of restful sleep.”

A separate, earlier study from Nielsen’s lab, published in 2015, raises another possibility: some of this might be self-fulfilling. Because the belief that cheese causes nightmares is already so widespread, simply expecting a bad dream after a late-night snack could be enough to help produce one, according to a summary of that research by the Australian outlet Delicious. The fear of the queso, then, might be doing almost as much work as the queso itself.

The study has limits. Nielsen told Food & Wine his team still needs to study more people across different ages, “walks of life, and with different dietary habits to determine if our results are truly generalizable to the larger population.” He added that “experimental studies are also needed to determine if people can truly detect the effects of specific foods on dreams.” His next planned study would have participants actually eat cheese before bed, rather than just asking them to recall.

Eating Late Is Its Own Nightmare Trigger

The study also found that eating late at night and eating heavily in the evening were both associated with poorer sleep quality and higher nightmare scores. Dr. Rybel Wix, a sleep specialist at HM Hospitales in Spain, explained why to Mujer.es: “Food and sleep don’t get along when we eat too much for dinner, or when we choose foods that are hard to digest right before going to bed. While the intestine is active and working through digestion, especially after a heavy, fatty, sugary, or heavily seasoned meal, the body devotes more energy and attention to the digestive process.”

Dr. Santana Miranda, of UNAM’s Sleep Disorders Clinic, offered a rough rule of thumb for how much of a buffer to leave. “It’s best to keep a reasonable schedule if the meal includes protein and fat. You need to leave a bit more time, around two hours,” he said. “But if it’s a different kind of dinner, like fruit, vegetables, or dairy products, it can be less than two hours.”

So, Should You Actually Quit Queso?

Not necessarily. Nielsen and his co-authors, Jade Radke, Claudia Picard-Deland, and Russell Arnold Powell, note in an essay for the University of British Columbia that the findings are correlational, not proof that cheese itself is scripting your dreams. But they also laid out what’s worth trying if your nights have been rough. They recommend eating lighter and earlier, since evening eating tracked with more negative dream content and worse sleep. Similarly, they say swapping in lactose-free dairy or naturally lower-lactose options like hard, aged cheeses if you’re intolerant; being mindful of trigger foods if you have allergies, since the anxiety around a reaction can bleed into dreams on its own; and keeping a short food-and-sleep log to spot your own patterns instead of guessing.

“If certain foods or dietary habits consistently lead to poor sleep or strange dreams,” the researchers wrote, “it’s worth taking these symptoms seriously.”

Tags: food, Nightmares