Does Dairy Ruin Sleep? New Study Says It's Possible

We've seen a lot of anecdotal evidence surrounding the claim that certain foods can give people bad dreams if eaten right before bed. A popular sitcom from the 80s and 90s had an episode showing the TV dad having nightmares after eating a sausage sandwich. Do foods like dairy ruin sleep, or is this all just old tales?

A study published on July 1, 2025 in the journal Frontiers in Psychology aims to find out. Researchers led by Dr. Tore Nielsen from the Université de Montréal and MacEwan University surveyed more than 1,000 students in Canada, surveying students primarily at MacEwan University. Researchers asked the students about the quality of their sleep, their eating habits, and any perceived correlations between the two. They found a strong link between dairy consumption before bed (especially among those with lactose intolerance or food allergies) and increased nightmare frequency and disrupted sleep.

"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!"

Roughly one out of three respondents reported regular nightmares, with women being more likely to remember their dreams and have nightmares. Women were also more likely to report food allergies (about twice as likely as the males in the study). Other interesting findings came about too, like the 40% of participants who thought eating late or eating certain types of foods could impact sleep, and the 25% of participants who thought particular foods make sleep worse. Most of the participants who thought a certain type of food was responsible for poor sleep quality thought sweets, spicy foods, or dairy were the foods that could be causing the problem.

"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."

If you have lactose intolerance or sensitivity, stay away from the dairy, especially right before bed. Gastrointestinal symptoms experienced by lactose-intolerant or sensitive individuals may cause micro‑arousals during sleep, leading to vivid or disturbing dreams. It's best to avoid dairy before bed if you’re sensitive to it, although further research is needed to confirm and expand upon these findings to develop proper guidance protocols for those in different demographic categories.