Dreams of the Rarebit Fiend: Dietary Correlates of Sleep and Dreaming

Overview

For centuries, folklore and bedtime stories have suggested a mysterious connection between food and our dreams. Perhaps the most famous example is Winsor McCay's early 20th-century cartoon series, "Dreams of the Rarebit Fiend."

In it, the characters often blamed their strange and wild dreams on the spicy cheese dish Welsh rarebit. Though the cartoons were satirical, they were based on a common belief: that what we eat, especially late at night, can affect how we sleep and what we dream.

However, is there any scientific evidence to support this claim? A recent large-scale study by Canadian researchers dives into this curious topic, and what they found was astounding!

Let us take a look together!

The Diet, Sleep, and Dreaming Study

In a groundbreaking study published in the Frontiers in Psychology Journal, Canadian scientists explored the effects of food on sleep and dreams.^[1]

Although folk beliefs have long held that what you eat influences how you sleep, there is little evidence to support or refute them.

To investigate how food influences the sleeping and dreaming mind, the researchers created a detailed online survey that was distributed to a large cohort of undergraduate psychology students at MacEwan University in Canada.

Research Specifics

The survey was completed by 1,082 participants over a four-month period in early 2023, with the majority being young adults, with a mean age of just over 20.

The sample was diverse in terms of gender and ethnicity. Still, it was skewed towards women (roughly two-thirds of respondents).

The survey, which was housed on the Qualtrics platform, included a large number of standardized instruments as well as custom-developed items.

It addressed a wide range of topics, including dietary habits, food intolerances and allergies, sleep quality, dream recall, nightmare frequency, psychological well-being, and eating behavior.

In addition to these standardized instruments, the survey included a customized Food-Dependent Dreaming (FDD) Questionnaire, which asked participants whether they believed specific meals or eating at certain times influenced their dreams or sleep.

Respondents who answered affirmatively were asked to specify which meals they thought generated effects like more vivid, distressing, or weird dreams, as well as whether such effects were positive or bad.

The Three Hypotheses of the Study

Importantly, the researchers wanted to test three main ideas. The first hypothesis was the food-specific effects hypothesis, which suggests that certain foods may directly influence the nature of dreams, making them more vivid, strange, pleasant, or scary.

The second hypothesis was the food distress hypothesis, which suggests that discomfort related to food, particularly from substances like lactose or gluten, may alter the content of dreams by inducing physical symptoms during sleep.

The third hypothesis was the sleep-effects hypothesis, which posits that food alters our sleep patterns, which in turn affects the content and quality of our dreams.

The Key Findings

After looking at all of the data, here is what the scientists found:

1) Statistics on Dreams and Nightmares

Approximately one-third of respondents had regular nightmares.^[1] Women were more likely than men to remember their dreams, have inadequate sleep and nightmares, and have a food intolerance or allergy.

2) Food Influences on Sleep and Dreams

Many participants reported that their eating habits affected their sleep in some way. Approximately 40% of them reported that eating certain foods improved or impaired their sleep.

A total of 267 (or 24.7%) of the respondents said that consuming certain meals made their sleep worse, while 218 (or 20.1%) claimed that foods improved it.

Desserts and sweets (22.7%), spicy food (19.5%), and dairy (15.7%) were the most often cited culprits for poor sleep. In contrast, fruit (17.6%), herbal tea (13.4%), and vegetables (11.8%) were considered to contribute to its improvement.

Surprisingly, only about 5.5% of the participants reported that they thought food affected their dreams. The researchers referred to these individuals as Food-Dependent Dreamers (FDD+).

Although this number was significantly lower than the 17.8% found in the team's previous study from 2015, those who reported experiencing food-related dreaming effects showed clear and measurable differences from those who did not.^[2]

In particular, FDD+ participants had more frequent and severe nightmares, as shown by higher scores on the Nightmare Disorder Index (NDI).

They were also more likely to report having strange, scary, or vivid dreams. Interestingly, they often attributed these effects to specific types of food, with desserts and sweets (30%) and dairy products (21%) being the most common. Spicy foods and meat were next on the list.

On the other hand, people said that foods like fruits, vegetables, and herbal teas helped them sleep better more often.

These results support the food-specific effects hypothesis, which suggests that certain foods may directly influence our dreaming patterns by altering the functioning of our brains and bodies during sleep.

Lactose Intolerance: A Cause of Nightmares

One of the most interesting findings was about lactose intolerance. People who said they were lactose intolerant were much more likely to say that their sleep got worse and that they had more or worse nightmares.

The story didn't end there, though. The researchers went even further by using mediation analysis to find out if this relationship was indirect. If gastrointestinal (GI) distress was a factor.

The results were evident. Some GI symptoms, like bloating, cramping, or indigestion, were found to be partially linked to lactose intolerance and nightmares.

This finding suggests that it may not be the lactose itself that causes nightmares, but the discomfort that comes from eating it that shows up in dreams as scary images or emotional distress.

Also, people with food allergies (like peanuts, tree nuts, shellfish, and other sensitivities) had higher NDI scores. These allergies weren't directly linked to GI symptoms, such as lactose intolerance. Still, their connection to anxiety and hypervigilance may make dreams more negative.

Sleep Quality and the Role of Healthy Eating Habits

The study found that general eating habits and diet quality had a significant effect on both dream recall and the emotional tone of dreams, in addition to specific intolerances.

People who said they ate healthier, especially those who scored high on the Body–Food Choice Congruence subscale of the Intuitive Eating Scale (i.e., choosing foods that "make my body perform well" or "give me energy and stamina"), were more likely to remember their dreams. They were also more likely to say that their dreams were neutral or positive.

On the other hand, unhealthy eating habits, like eating at night or in the evening, overeating when not hungry, and not paying attention to internal hunger cues, were linked to more negative dreams and worse nightmares. GI symptoms and emotional distress, especially anxiety and depression, also made these connections stronger.

Interestingly, eating between dinner and bedtime, which is called "evening eating," was especially linked to having nightmares. People who ate a lot during these hours not only reported sleeping worse but also experienced more emotionally damaging dreams.

But this behavior didn't seem to affect how often people remembered their dreams. This finding suggests that eating in the evening doesn't always help you remember more dreams. Still, it might make the ones you do remember more unpleasant.

These results support the sleep-effects hypothesis, which says that what you eat affects how well you sleep, which in turn affects the content and emotional tone of your dreams.

There has long been a connection between poor sleep and dreams that are fragmented and emotionally charged. This study adds to that link.

Why This Study Matters

This study does more than just confirm what old wives' tales say. It prompts us to consider sleep health in a way that has real-world implications, particularly when it comes to non-drug approaches.

If certain foods, especially those that make you feel bad, can keep you from sleeping and make your nightmares worse, then changing your diet might be a good way to deal with sleep problems.

This point is crucial for people with PTSD, many of whom have nightmares that last for a long time.^[3] Some early studies even suggest that following diets like the Mediterranean diet may help with PTSD symptoms, possibly by changing the gut-brain axis.^[4]

The study also prompts us to consider the gut as a means of accessing the dreaming brain. The link between GI pain and emotionally charged dreams highlights the complexity of the conversation between our gut, brain, and emotions. This finding is something that neuroscience is increasingly investigating.

Concerning the following steps, Dr. Tore Nielsen, lead author of the study, stated that more studies involving persons of all ages, walks of life, and dietary habits are required to evaluate whether our findings are truly generalizable to a larger population.^[5]

"Experimental research is also required to determine whether people can accurately recognise the impact of various foods on dreams. We'd like to conduct a study in which people consume cheese products rather than control foods before going to bed to determine if this affects their sleep or nightmares," Nielson said.

Final Thoughts

So, should you stop eating cheese toast late at night because you're afraid of having bad dreams? Not always.

This study reveals that what you eat and how you digest it can impact your dreams, particularly if you have food sensitivities.

Suppose you often wake up from strange, scary dreams and feel bloated or uncomfortable. In that case, consider what you eat for dinner, especially the amount of dairy and sugar you consume.

References:

Nielsen, T., Radke, J., Picard-Deland, C., & Powell, R. A. (2025). More dreams of the rarebit fiend: food sensitivity and dietary correlates of sleep and dreaming. Frontiers in Psychology, 16, 1544475. https://doi.org/10.3389/fpsyg.2025.1544475
Nielsen, T., & Powell, R. A. (2015). Dreams of the Rarebit Fiend: food and diet as instigators of bizarre and disturbing dreams. Frontiers in psychology, 6, 47. https://doi.org/10.3389/fpsyg.2015.00047
Pillar, G., Malhotra, A., & Lavie, P. (2000). Post-traumatic stress disorder and sleep-what a nightmare!. Sleep medicine reviews, 4(2), 183–200. https://doi.org/10.1053/smrv.1999.0095
Ke, S., Wang, X.-W., Ratanatharathorn, A., Huang, T., Roberts, A. L., Grodstein, F., Kubzansky, L. D., Koenen, K. C., & Liu, Y.-Y. (2023). Association of probable post-traumatic stress disorder with dietary pattern and gut microbiome in a cohort of women. Nature Mental Health, 1(11), 900–913. https://doi.org/10.1038/s44220-023-00145-6
Frontiers. (2025, July 1). Is cheese secretly fueling your nightmares? Science weighs in. Science Daily. https://www.sciencedaily.com/releases/2025/07/250701020653.htm