Is it true that eating cheese for dinner causes nightmares?

A recent Canadian study has suggested a possible link between lactose intolerance and the frequency of nightmares, reviving the long-held myth that cheese causes disturbing dreams.

Although the finding is intriguing, the research has, as we will see, significant limitations. Despite the media attention, we are still far from being able to confirm that diet has a direct and proven influence on dreams.

For decades, there has been a belief that eating certain foods or having dinner late can negatively affect the quality of one's night's sleep and alter the content of dreams , making them more vivid, disturbing, or even nightmarish.

The "usual suspects" include heavy meals, highly seasoned foods, sweets high in refined sugar, and, most frequently, dairy products. Is there any scientific basis for this perception?

Another Canadian survey conducted in 2015 already explored the issue. The study collected responses from 396 people and revealed that 17.8% of participants associated some type of food with unpleasant dreams. Specifically, dairy products (milk, cheese, ice cream) and sugary sweets were the most frequently mentioned products .

On the other hand, some participants also stated that certain foods, such as fruits or vegetables, generated positive dreams, which points to a possible subjective and symbolic dimension in the relationship between food and dream content.

Another relevant factor is dinner time. Various studies have shown that eating dinner late —particularly within two hours of bedtime—can disrupt the quality of sleep.

The new study, published in Frontiers in Psychology, revisits the issue and once again points to dairy as the main culprit. How strong is the evidence?

The scientists—led by Tore Nielsen, the same researcher who led the 2015 study—interviewed 1,082 college students. The questionnaire included questions about sleep quality, dream frequency and intensity, eating habits, mental and physical health, and any perceived relationship between food consumption and dream content.

An important objective was to analyze subjective beliefs about whether certain types of food affected their sleep. This approach, although useful for identifying social perceptions, has a crucial limitation: it relies on self-reports, without objective verification of the physiological conditions of sleep or digestion.

The results revealed several interesting facts:

Approximately one-third of respondents reported experiencing frequent nightmares, although women were more likely to recall their dreams and report sleep disturbances.

In total, 40% of participants felt that eating late or eating certain foods negatively affected their sleep, and 25% said that certain foods worsened their sleep quality. Among the most frequently cited foods were sweets, spicy foods, and dairy products .

5.5% of respondents said that what they ate directly influenced the content or tone of their dreams, and many described dairy and sweets as making them more vivid or disturbing.

Finally, one of the most cited findings was the relationship between lactose intolerance and nightmares: those who reported this disorder also reported nocturnal gastrointestinal symptoms, poorer sleep quality, and a higher frequency of negative dreams.

Interpreting these data requires caution. As Tore Nielsen explained, the results suggest an association, but do not prove causality. That is, the coincidence of two phenomena (eating cheese and having a nightmare, for example) does not imply that one causes the other. The study was not designed to establish a cause-and-effect relationship between dairy consumption and the occurrence of distressing dreams.

Furthermore, this was not a controlled experiment, but rather a survey based on subjective perceptions. No physiological measurements or polysomnographic sleep recordings were used, nor was there any objective control over which foods were consumed, in what quantities, or under what conditions.

Another aspect to keep in mind is that nighttime digestive discomfort can actually disrupt sleep. Large-scale studies show that symptoms such as abdominal pain, bloating, gas, and reflux are associated with increased sleep fragmentation, frequent awakenings, and poor sleep quality.

Furthermore, among patients with functional gastrointestinal disorders such as irritable bowel syndrome, a decrease in deep sleep (stage N3) and an increase in microarousals have been observed. These interruptions, although brief or imperceptible, can generate intermediate states of consciousness during which dreams become more vivid, fragmented, or emotionally intense, especially if physical discomfort is present.

However, this doesn't mean cheese is the culprit. People often tend to identify dairy as the cause of their discomfort due to popular discourse and narratives spread on social media, rather than proven personal evidence. Furthermore, in everyday life, we don't usually eat foods in isolation, making it difficult to attribute a specific effect to a single ingredient.

In their conclusions, the authors of the study emphasize the need to replicate it with larger and more diverse samples—in age, culture, and dietary patterns—as well as employ more rigorous methods, such as experimental studies with controlled groups, sleep monitoring, and food administration under controlled conditions.

The study offers an interesting insight into how diet could, in some cases, interfere with nighttime sleep, especially in people with food intolerances. However, there is still no conclusive evidence to support the claim that dairy—or any specific food—directly causes nightmares.

This article was originally published on The Conversation .