Cheese Really Does Give You Nightmares, Study Confirms

That old wives’ tale about cheese causing bad dreams? Scientists have found it might actually be true—at least for people who can’t properly digest dairy.

A new study of over 1,000 university students reveals a strong link between lactose intolerance and nightmares, potentially settling centuries of folk wisdom with hard data.

Researchers at Université de Montréal and MacEwan University discovered that people with lactose intolerance experience significantly more nightmares than those who can digest dairy without problems. The culprit appears to be gastrointestinal discomfort that disrupts sleep and influences dream content.

Ancient Belief Meets Modern Science

“Nightmare severity is robustly associated with lactose intolerance and other food allergies,” explained Dr. Tore Nielsen of Université de Montréal, the study’s lead author. “These new findings imply that changing eating habits for people with some food sensitivities could alleviate nightmares. They could also explain why people so often blame dairy for bad dreams!”

The research, published in Frontiers in Psychology, surveyed 1,082 students about their sleep quality, eating habits, and any connections they noticed between food and dreams. While folk beliefs have long suggested that what you eat affects how you sleep, this study provides some of the first scientific evidence to support those claims.

Women Report More Food-Related Sleep Issues

The findings revealed several interesting patterns. About one-third of participants reported regular nightmares, with women nearly twice as likely as men to report food intolerances or allergies. Women were also more likely to remember their dreams and report poor sleep quality overall.

Key findings from the study include:

• 40% of students believed eating late at night or specific foods affected their sleep
• 25% thought particular foods made their sleep worse
• Only 5.5% felt that food affected the tone of their dreams
• Among those who noticed dream effects, 31% blamed sweets and 22% blamed dairy

“We are routinely asked whether food affects dreaming—especially by journalists on food-centric holidays,” Nielsen noted. “Now we have some answers.”

The Stomach-Dream Connection

The most compelling finding centered on lactose intolerance. Students who couldn’t properly digest dairy showed clear associations between their condition, gastrointestinal symptoms, nightmares, and poor sleep quality. This suggests that physical discomfort from eating dairy creates a domino effect—stomach pain leads to disrupted sleep, which in turn affects dream content.

“Nightmares are worse for lactose intolerant people who suffer severe gastrointestinal symptoms and whose sleep is disrupted,” Nielsen explained. “This makes sense, because we know that other bodily sensations can affect dreaming.”

The mechanism appears straightforward: when lactose-intolerant individuals consume dairy, their bodies struggle to break down the milk sugar, leading to gas, bloating, and stomach pain. These uncomfortable sensations can persist into sleep, potentially triggering more vivid or disturbing dreams.

Broader Implications for Sleep Health

Beyond the dairy connection, researchers found that people with healthier eating habits generally experienced better dream recall and fewer negative dreams. Those who ate less nutritiously were more likely to have disturbing dreams and less likely to remember them at all.

The study also revealed an intriguing trend: fewer students in this research reported food-dream connections compared to a similar study conducted eleven years earlier. The researchers speculate that improved awareness of food intolerances may mean people are better at avoiding problematic foods before bedtime.

While the lactose intolerance-nightmare connection appears solid, Nielsen acknowledges that much remains unknown about how diet influences sleep and dreams. The relationship could work in multiple directions—poor sleep might lead to poor eating habits, or other factors might influence both simultaneously.

“We need to study more people of different ages, from different walks of life, and with different dietary habits to determine if our results are truly generalizable,” Nielsen said. The research team is now planning controlled experiments, including studies where participants would consume cheese versus control foods before sleep to directly test the effects on dreams.

For now, the advice seems simple: if you’re lactose intolerant and experiencing frequent nightmares, that late-night pizza or bedtime ice cream might be worth reconsidering.