When cheese can be the cause of your nightmares

A group of scientists has discovered that consuming too much dairy could ruin your sleep. Researchers interviewed more than 1,000 students about their sleep quality, their eating habits, and any perceived links between the two , and found a strong association between nightmares and lactose intolerance, possibly because gas or stomach pain at night can disrupt dreams.

"Nightmare severity is closely linked to lactose intolerance and other food allergies," says Dr. Tore Nielsen, lead author of the paper published in Frontiers in Psychology . "These new findings imply that changing the eating habits of people with certain food sensitivities could alleviate nightmares. They may also explain why people often blame dairy for nightmares!"

Although it has long been believed that diet affects sleep, there is very little evidence to prove or refute this . To investigate, researchers surveyed 1,082 students at MacEwan University . They asked them about sleep timing and quality, dreams and nightmares, and any perceived associations between different types of dreams and different foods. They also inquired about the participants' mental and physical health and their relationship with food.

Approximately one-third of respondents reported frequent nightmares. Women were more likely to recall their dreams and report poor sleep and nightmares, and almost twice as likely as men to report food intolerance or allergy. About 40% of participants said they believed eating late or eating certain foods affected their sleep; approximately 25% thought certain foods could worsen it. People with less healthy diets were more likely to have negative dreams and less likely to recall them.

The role of sweets

"We're frequently asked whether food affects dreams, especially by journalists who travel on food vacations," Nielsen said. "Now we have some answers." The majority of participants who attributed their poor sleep to food believed sweets, spicy foods, or dairy products were responsible. Only a comparatively small proportion ( 5.5 percent of respondents ) felt that what they ate affected the vividness of their dreams, but many of them explained that sweets or dairy products made their dreams more disturbing or strange.

When comparing reports of food intolerance with those of nightmares and poor sleep , the authors found that lactose intolerance was associated with gastrointestinal symptoms, nightmares, and poor sleep quality . Dairy consumption may cause gastrointestinal distress, and the resulting discomfort may impact dreams and sleep quality.

“ Nightmares are worse for people with lactose intolerance who suffer from severe gastrointestinal symptoms and whose sleep is disrupted,” Nielsen said. “This makes sense, since we know that other bodily sensations can affect sleep . Nightmares can be very disturbing, especially if they occur frequently, as they tend to wake people up in a dysphoric state. They can also lead to sleep avoidance behaviors. Both of these symptoms can prevent restful sleep.”

This might also explain why fewer participants reported a relationship between their diet and their dreams than in a previous study by Nielsen and her colleague, Dr. Russell Powell of MacEwan University, conducted eleven years earlier with a similar population. Greater awareness of food intolerances could mean that the students in the current study ate fewer foods that are likely to trigger their intolerances and affect their sleep. If so, simple dietary interventions could help people improve their sleep and overall health .

However, aside from the strong link between lactose intolerance and nightmares, it's not clear how the relationship between sleep and diet works. It's possible that people sleep worse because they eat worse, but it's also possible that they eat poorly 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 social backgrounds, and with different eating habits to determine if our results are truly generalizable to the general population," Nielsen explains. " Experimental studies are also needed to determine if people can actually detect the effects of specific foods on dreams. We would like to conduct a study in which we ask people to consume cheese products versus a control food before bed to see if this disrupts their sleep or dreams," she concludes.