Most students don’t blame food for their dreams, but for those with lactose intolerance, that midnight snack could be fueling restless nights and unsettling nightmares.
Study: More dreams of the rarebit fiend: food sensitivity and dietary correlates of sleep and dreaming. Image Credit: Krakenimages.com / Shutterstock
Scientists have found that lactose intolerance, not dairy itself, may be linked to nightmares and poor sleep in some individuals. Researchers questioned more than 1,000 undergraduate psychology students at MacEwan University about the quality of their sleep, their eating habits, and any perceived link between the two. They found a significant association between nightmares and lactose intolerance, especially among those experiencing gastrointestinal (GI) symptoms, potentially because gas or stomach pain during the night affects people's dreams.
"Nightmare severity is robustly associated with lactose intolerance and other food allergies," said Dr Tore Nielsen of Université de Montréal, lead author of the article in Frontiers in Psychology. "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!"
Sweet dreams?
Although folk beliefs have long held that what you eat affects how you sleep, there's very little evidence to prove or disprove them. To investigate, researchers surveyed 1,082 students at MacEwan University. They inquired about sleep time and quality, dreams and nightmares, and any perceived associations between different kinds of dreams and various foods. They also asked about participants' mental and physical health and their relationship with food.
About a third of respondents reported regular nightmares. Women were more likely to remember their dreams and to report poor sleep and nightmares, and nearly twice as likely as men to report a food intolerance or allergy. Approximately 40% of participants reported that they believed eating late at night or consuming specific foods affected their sleep; roughly 25% believed particular foods could worsen their sleep. However, only a small minority (5.5%) believed that eating late or consuming certain foods affected their dreams at all. People who ate less healthily were more likely to experience negative dreams and less likely to recall their dreams.
"We are routinely asked whether food affects dreaming - especially by journalists on food-centric holidays," said Nielsen. "Now we have some answers."
Protagonists in the cartoons of Winsor McCay frequently blamed their presleep ingestion of cheese dishes for occurrences of bizarre dream and nightmare events. (Reproduced from “Dream of the Rarebit Fiend” by Windsor McCay, Dream of the Rarebit Fiend by Winsor McCay : Winsor McCay : Free Download, Borrow, and Streaming : Internet Archive, CC0).
Cheesy culprits
Most participants who blamed their poor sleep on food believed that sweets, spicy foods, or dairy products were the culprits. Only a comparatively small proportion - 5.5% of respondents - felt that what they ate affected the tone of their dreams, but many of these individuals reported that they believed sweets or dairy products made their dreams more disturbing or bizarre.
When the authors compared reports of food intolerances to reports of bad dreams and poor sleep, they found that lactose intolerance was associated with gastrointestinal symptoms, nightmares, and low sleep quality. Notably, while participants perceived dairy as a culprit, the robust link was specific to those with lactose intolerance who also experienced GI symptoms. It's possible that consuming dairy in individuals with lactose intolerance can trigger gastrointestinal distress, and the resulting discomfort may impact people's sleep patterns and the quality of their rest.
"Nightmares are worse for lactose intolerant people who suffer severe gastrointestinal symptoms and whose sleep is disrupted," said Nielsen. "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 produce sleep avoidance behaviors. Both symptoms can rob you of restful sleep."
Eat well to sleep well?
This could also explain why fewer participants reported a link between their food and their dreams than in a previous study by Nielsen and his colleague, Dr Russell Powell of MacEwan University, conducted eleven years earlier on a similar population. Improved awareness of food intolerances could mean that the students in the present study ate fewer foods likely to activate their intolerances and affect their sleep. If this is the case, then simple dietary interventions could potentially help people improve their sleep and overall health.
However, besides the robust link between lactose intolerance and nightmares, the study also found that food allergies and gluten intolerance were associated with perceptions of food-dependent dreaming, though these effects were less pronounced. It's not clear how the relationship between sleep and diet works. It's possible that people sleep less well because they eat less well, but it's also likely that people don't eat well because they don't sleep well, or that another factor influences both sleep and diet. Further research will be needed to confirm these links and identify the underlying mechanisms.
"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 to the larger population," said Nielsen. "Experimental studies are also needed to determine if people can truly detect the effects of specific foods on dreams. We would like to run a study in which we ask people to ingest cheese products versus some control food before sleep to see if this alters their sleep or dreams."
In summary, while most participants did not report that food affected their dreams, the findings highlight a specific link between lactose intolerance, GI symptoms, and nightmares. The results suggest that for some individuals, particularly those with specific food sensitivities, dietary choices may have a significant impact on sleep quality and dream experiences.
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